Zonisamide is an active pharmaceutical ingredient in the Other Antiepileptics group (N03AX). The information below is compiled per regulator from the product labels on record, with direct links to the original documents.
GBOfficial regulatory label· revised December 12, 2025[1]
1). • adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation, in adults, adolescents, and children aged 6 years and above.
How to take
GB
USUnited States· FDA
3 products
Uses
USOfficial regulatory label· revised August 1, 2025[2]
INDICATIONS AND USAGE
Zonisamide capsules are indicated as adjunctive therapy in the treatment of partial seizures in adults with epilepsy.
How to take
US
EUEuropean Union· EMA
2 products
Uses
EUOfficial regulatory label· revised October 22, 2025[3]
1); • adjunctive therapy in the treatment of partial seizures, with or without secondary generalisation, in adults, adolescents, and children aged 6 years and above.
How to take
EU
Drug interactions
Known interactions involving Zonisamide. Select one for details. This list is informational and not a complete interaction checker.
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[1]MHRA (UK) · PL002891995 · revised December 12, 2025
[2]FDA DailyMed · 061fdccc-d08e-4e… · revised August 1, 2025 [PDF]
[3]European Medicines Agency · EMEA/H/C/004127 · revised October 22, 2025
[4]OpenFDA adverse-event reports (US), 12 months ending June 4, 2026.
Information on this page is compiled from public regulatory records. Drugvu is not affiliated with any regulator or pharmaceutical manufacturer. This is not medical advice. Always consult a qualified healthcare professional.
Posology Adults Dosage escalation and maintenance Zonisamide Teva may be taken as monotherapy or added to existing therapy in adults. The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 1.
Some patients, especially those not taking CYP3A4- inducing agents, may respond to lower doses. 4). In clinical studies of adult patients, dose reductions of 100 mg at weekly intervals have been used with concurrent adjustment of other antiepileptic medicine doses (where necessary).
Table 1. Adults – recommended dosage escalation and maintenance regimen Treatment Regimen Titration Phase Usual Maintenance Dose Week 1 + 2 Week 3 + 4 Week 5 + 6Monotherapy - Newly diagnosed adult patients 100 mg/day (once a day) 200 mg /day (once a day) 300 mg / day (once a day) 300 mg per day (once a day).
If a higher dose is required: increase at two-weekly intervals in increments of 100 mg up to a maximum of 500 mg. 5) 50 mg/day (in two divided doses) 100 mg /day (in two divided doses) Increase at weekly intervals in increments of 100 mg 300 to 500 mg per day (once a day or two divided doses).
Week 1 + 2 Week 3 + 4 Week 5 to 10- without CYP3A4- inducing agents; or with renal or hepatic impairment 50 mg/day (in two divided doses) 100 mg / day (in two divided doses) Increase at two-weekly intervals in increments of up to 100 mg 300 to 500 mg per day (once a day or two divided doses).
Some patients may respond to lower doses. General dosing recommendations for Zonisamide Teva in special patient populations Paediatric population (aged 6 years and above) Dosage escalation and maintenance Zonisamide Teva must be added to existing therapy for paediatric patients aged 6 years and above.
The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 2. Some patients, especially those not taking CYP3A4-inducing agents, may respond to lower doses. 4: Paediatric population).
Table 2. 5) 1 mg/kg/day (once a day) Increase at weekly intervals in increments of 1 mg/kg 6 to 8 mg/kg/day (once a day) 300 - 500 mg/day (once a day) Week 1 + 2 Weeks ≥ 3- without CYP3A4- inducing agents 1 mg/kg/day (once a day) Increase at two-weekly intervals in increments of 1 mg/kg 6 to 8 mg/kg/day (once a day) 300 - 500 mg/day (once a day) Note: a.
To ensure a therapeutic dose is maintained the weight of a child should be monitored and the dose reviewed as weight changes occur up to a weight of 55kg. The dose regime is 6-8 mg/kg/day up to a maximum dose of 500 mg/day. The safety and efficacy of zonisamide in children aged below 6 years or those below 20 kg have not yet been established.
There are limited data from clinical studies in patients with a body weight of less than 20 kg. Therefore children aged 6 years and above and with a body weight less than 20 kg should be treated with caution. It is not always possible to precisely achieve the calculated dose with the commercially available capsule strengths of Zonisamide Teva.
In these cases it is therefore recommended that the zonisamide total dose should be rounded up or down to the nearest available dose that can be achieved with commercially available capsule strengths of Zonisamide Teva (25 mg, 50 mg and 100 mg).
4). e. in accordance with the schedule in Table 3). Table 3. Paediatric population (aged 6 years and above) – recommended down- titration schedule Weight Decrease at weekly intervals in increments of: 20 – 28 kg 25 to 50 mg / day* 29 – 41 kg 50 to 75 mg / day* 42 – 55 kg 100 mg / day* >55 kg 100 mg / day* Note: * All doses are once daily.
Elderly Caution should be exercised at initiation of treatment in elderly patients as there is limited information on the use of zonisamide in these patients. 8). Renal impairment Caution must be exercised in treating patients with renal impairment, as there is limited information on use in such patients and a slower titration of Zonisamide Teva might be required.
Since zonisamide and its metabolites are excreted renally, it should be discontinued in patients who develop acute renal failure or where a clinically significant sustained increase in serum creatinine is observed. In subjects with renal impairment, renal clearance of single doses of zonisamide was positively correlated with creatinine clearance.
The plasma AUC of zonisamide was increased by 35% in subjects with creatinine clearance < 20 ml/min. Hepatic impairment Use in patients with hepatic impairment has not been studied. Therefore use in patients with severe hepatic impairment is not recommended.
Caution must be exercised in treating patients with mild to moderate hepatic impairment, and a slower titration of Zonisamide Teva may be required. Method of administration Zonisamide Teva Capsules, Hard are for oral use. 2).
This is not medical advice. Consult a qualified healthcare professional.
Side effects & warnings
GBOfficial regulatory label· Adverse reactions· revised December 12, 2025[1]
Summary of the safety profile Zonisamide has been administered to over 1,200 patients in clinical studies, more than 400 of whom received zonisamide for at least 1 year. In addition there has been extensive post-marketing experience with zonisamide in Japan since 1989 and in the USA since 2000.
It should be noted that Zonisamide Teva is a benzisoxazole derivative, which contains a sulphonamide group. 4). The most common adverse reactions in controlled adjunctive-therapy studies were somnolence, dizziness and anorexia. The most common adverse reactions in a randomised, controlled monotherapy trial comparing zonisamide with carbamazepine prolonged release were decreased bicarbonate, decreased appetite, and decreased weight.
8%. 7%. Tabulated list of adverse reactions Adverse reactions associated with zonisamide obtained from clinical studies and post- marketing surveillance are tabulated below. The frequencies are arranged according to the following scheme: very common ≥ 1/10 common ≥ 1/100 to < 1/10 uncommon ≥ 1/1,000 to < 1/100 rare ≥ 1/10,000 to < 1/1,000 very rare < 1/10,000 not known cannot be estimated from the available data Table 4.
Adverse reactions associated with zonisamide obtained from adjunctive use clinical studies and post-marketing surveillance System Organ Class (MedDRA terminology) Very Common Common Uncommon Very Rare Infections and infestation Pneumonia Urinary tract infection Blood and lymphatic system disorders Ecchymosis Agranulocytosis Aplastic anaemia Leucocytosis Leucopoenia Lymphadenopathy Pancytopenia, Thrombocytopenia Immune system disorders Hypersensitivity Drug-induced hypersensitivity syndrome Drug rash with eosinophilia and systemic symptoms Metabolism and nutrition disorders Anorexia Hypokalaemi a Metabolic acidosis Renal tubular acidosis Psychiatric Disorders Agitation Irritability Confusional state Depression Affect lability Anxiety Insomnia Psychotic disorder Anger Aggression Suicidal ideation Suicide attempt Hallucination Nervous system disorders Ataxia Dizziness Memory impairment Somnolence Bradyphrenia Disturbance in attention Nystagmus Paraesthesia Speech disorder Tremor Convulsion Amnesia Coma Grand mal seizure Myasthenic syndrome Neuroleptic malignant syndrome Status epilepticus Eye disorders Diplopia Angle closure glaucoma Eye pain Myopia Vision blurred Visual acuity reduced Respiratory, thoracic and mediastinal disorders Dyspnoea Pneumonia aspiration Respiratory disorder Hypersensitivity-type Pneumonitis Gastrointestin al disorders Abdominal pain Constipation Diarrhoea Dyspepsia Nausea Vomiting Pancreatitis Hepatobiliary disorders Cholecystitis Cholelithiasis Hepatocellular damage Skin and subcutaneous tissue Rash Pruritis Alopecia Anhidrosis Erythema multiforme Stevens-Johnson disorders syndrome Toxic epidermal necrolysis Musculoskelet al and connective tissue disorders Rhabdomyolysis Renal and urinary disorders Nephrolithiasis Calculus urinary Hydronephrosis Renal failure Urine abnormality General disorders and administratio n site conditions Fatigue Influenza-like illness Pyrexia Oedema peripheral Investigations Decreased bicarbonate Weight decreased Blood creatine phosphokinase increased Blood creatinine increased Blood urea increased Liver function tests abnormal Injury, poisoning and procedural complications Heat stroke In addition there have been isolated cases of Sudden Unexplained Death in Epilepsy Patients (SUDEP) receiving zonisamide.
Table
GBOfficial regulatory label· Warnings and precautions· revised December 12, 2025[1]
Unexplained rash Serious rashes occur in association with zonisamide therapy, including cases of Stevens-Johnson syndrome. Consideration must be given to discontinuing Zonisamide Teva in patients who develop an otherwise unexplained rash.
All patients who develop a rash while taking Zonisamide Teva must be closely supervised, with additional levels of caution applied to those patients receiving concomitant antiepileptic agents that may independently induce skin rashes.
Withdrawal seizures In accordance with current clinical practice, discontinuation of Zonisamide Teva in patients with epilepsy must be accomplished by gradual dose reduction, to reduce the possibility of seizures on withdrawal. There are insufficient data for the withdrawal of concomitant antiepileptic medicines once seizure control with Zonisamide Teva has been achieved in the add-on situation, in order to reach monotherapy with Zonisamide Teva.
Therefore, withdrawal of concomitant anti-epileptic medicinal products must be undertaken with caution. Sulphonamide reactions Zonisamide Teva is a benzisoxazole derivative, which contains a sulphonamide group. Serious immune based adverse reactions that are associated with medicinal products containing a sulphonamide group include rash, allergic reaction and major haematological disturbances, including aplastic anaemia, which very rarely can be fatal.
Cases of agranulocytosis, thrombocytopenia, leukopenia, aplastic anaemia, pancytopenia and leucocytosis have been reported. There is inadequate information to assess the relationship, if any, between dose and duration of treatment and these events.
Acute myopia and secondary angle closure glaucoma A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in adult and paediatric patients receiving zonisamide. Symptoms include acute onset of decreased visual acuity and/or ocular pain.
Ophthalmologic findings can include myopia, anterior chamber shallowing, and ocular hyperaemia (redness) and increased intraocular pressure. This syndrome may be associated with supraciliary effusion resulting in anterior displacement of the lens and iris, with secondary angle closure glaucoma.
This is not medical advice. Consult a qualified healthcare professional.
Who should not take it
GBOfficial regulatory label· Contraindications· revised December 12, 2025[1]
1 or to sulphonamides.
This is not medical advice. Consult a qualified healthcare professional.
Zonisamide capsules are recommended as adjunctive therapy for the treatment of partial seizures in adults. Safety and efficacy in pediatric patients below the age of 16 have not been established. Zonisamide capsules should be administered once or twice daily, using 25 mg, 50 mg or 100 mg capsules.
Zonisamide capsules are given orally and can be taken with or without food. Capsules should be swallowed whole. Adults over Age 16 The prescriber should be aware that, because of the long half-life of zonisamide, up to two weeks may be required to achieve steady state levels upon reaching a stable dose or following dosage adjustment.
Although the regimen described below is one that has been shown to be tolerated, the prescriber may wish to prolong the duration of treatment at the lower doses in order to fully assess the effects of zonisamide at steady state, noting that many of the side effects of zonisamide are more frequent at doses of 300 mg per day and above.
Although there is some evidence of greater response at doses above 100-200 mg/day, the increase appears small and formal dose-response studies have not been conducted. The initial dose of zonisamide should be 100 mg daily. After two weeks, the dose may be increased to 200 mg/day for at least two weeks.
It can be increased to 300 mg/day and 400 mg/day, with the dose stable for at least two weeks to achieve steady state at each level. Evidence from controlled trials suggests that zonisamide doses of 100-600 mg/day are effective, but there is no suggestion of increasing response above 400 mg/day (see CLINICAL PHARMACOLOGY, Clinical Studies subsection ).
There is little experience with doses greater than 600 mg/day. Patients with Renal or Hepatic Disease Because zonisamide is metabolized in the liver and excreted by the kidneys, patients with renal or hepatic disease should be treated with caution, and might require slower titration and more frequent monitoring (see CLINICAL PHARMACOLOGY and PRECAUTIONS ).
This is not medical advice. Consult a qualified healthcare professional.
Most-reported reactions to the US regulator (12 mo to June 4, 2026): 729 reports total. [4]
Seizure 93
Off Label Use 87
Drug Ineffective 70
Drug Reaction With Eosinophilia And Systemic Symptoms 41
Product Dose Omission Issue 35
Multiple-Drug Resistance 33
Somnolence 30
Dizziness 29
Nausea 29
Fatigue 27
Product Use Issue 27
Diarrhoea 25
Side effects & warnings
USOfficial regulatory label· Adverse reactions· revised August 1, 2025[2]
ADVERSE REACTIONS
The most common adverse reactions with zonisamide (an incidence at least 4% greater than placebo) in controlled clinical trials and shown in descending order of frequency were somnolence, anorexia, dizziness, ataxia, agitation/irritability, and difficulty with memory and/or concentration.
In controlled clinical trials, 12% of patients receiving zonisamide as adjunctive therapy discontinued due to an adverse reaction compared to 6% receiving placebo. Approximately 21% of the 1,336 patients with epilepsy who received zonisamide in clinical studies discontinued treatment because of an adverse reaction.
The most common adverse reactions leading to discontinuation were somnolence, fatigue and/or ataxia (6%), anorexia (3%), difficulty concentrating (2%), difficulty with memory, mental slowing, nausea/vomiting (2%), and weight loss (1%).
Many of these adverse reactions were dose-related (see WARNINGS and PRECAUTIONS ) . Adverse Reaction Incidence in Controlled Clinical Trials Table 4 lists adverse reactions that occurred in at least 2% of patients treated with zonisamide in controlled clinical trials that were numerically more common in the zonisamide group.
In these studies, either zonisamide or placebo was added to the patient's current AED therapy. Table 4 Adverse Reactions in Placebo-Controlled, Add-On Trials (Events that occurred in at least 2% of zonisamide capsules-treated patients and occurred more frequently in zonisamide capsules-treated than placebo-treated patients) BODY SYSTEM/PREFERRED TERM ZONISAMIDE CAPSULES (N=269) % PLACEBO (N=230) % BODY AS A WHOLE Headache 10 8 Abdominal Pain 6 3 Flu Syndrome 4 3 DIGESTIVE Anorexia 13 6 Nausea 9 6 Diarrhea 5 2 Dyspepsia 3 1 Constipation 2 1 Dry Mouth 2 1 HEMATOLOGIS AND LYMPHATIC Ecchymosis 2 1 METABOLIC AND NUTRITIONAL Weight Loss 3 2 NERVOUS SYSTEM Dizziness 13 7 Ataxia 6 1 Nystagmus 4 2 Paresthesia 4 1 NEUROPSYCHIATRIC AND COGNITIVE DYSFUNCTION-ALTERED COGNITIVE FUNCTION Confusion 6 3 Difficulty Concentrating 6 2 Difficulty with Memory 6 2 Mental Slowing 4 2 NEUROPSYCHIATRIC AND COGNITIVE DYSFUNCTION-BEHAVIORAL ABNORMALITIES(NON - PSYCHOSIS- RELATED) Agitation/Irritability 9 4 Depression 6 3 Insomnia 6 3 Anxiety 3 2 Nervousness 2 1 NEUROPSYCHIATRIC AND COGNITIVE DYSFUNCTION-BEHAVIORAL ABNORMALITIES (PSYCHOSIS - RELATED) Schizophrenic/Schizophreniform Behavior 2 0 NEUROPSYCHIATRIC AND COGNITIVE DYSFUNCTION-CNS DEPRESSION Somnolence 17 7 Fatigue 8 6 Tiredness 7 5 NEUROPSYCHIATRIC AND COGNITIVE DYSFUNCTION-SPEECH AND LANGUAGE ABNORMALITIES Speech Abnormalities 5 2 Difficulties in Verbal Expression 2 <1 RESPIRATORY Rhinitis 2 1 SKIN AND APPENDAGES Rash 3 2 SPECIAL SENSES Diplopia 6 3 Taste Perversion 2 0 Other Adverse Reactions in Clinical Trials Zonisamide has been administered to 1,598 individuals during all clinical trials, only some of which were placebo-controlled.
The frequencies represent the proportion of the 1,598 individuals exposed to zonisamide who experienced an event on at least one occasion. All events are included except those already listed in the previous table or discussed in WARNINGS or PRECAUTIONS , trivial events, those too general to be informative, and those not reasonably associated with zonisamide.
Events are further classified within each category and listed in order of decreasing frequency as follows: frequent occurring in at least 1:100 patients; infrequent occurring in 1:100 to 1:1000 patients; rare occurring in fewer than 1:1000 patients.
Albuminuria, enuresis, bladder pain, bladder calculus, gynecomastia, mastitis, menorrhagia. POST MARKETING EXPERIENCE The following serious adverse reactions have been reported since approval and use of zonisamide capsules worldwide.
These reactions are reported voluntarily from a population of uncertain size; therefore, it is not possible to estimate their frequency or establish a causal relationship to drug exposure. Acute pancreatitis, rhabdomyolysis, increased creatine phosphokinase, drug reaction with eosinophilia and systemic symptoms (DRESS), acute myopia and secondary angle closure glaucoma, and hyperammonemia and encephalopathy (see WARNINGS ).
To report SUSPECTED ADVERSE REACTIONS, contact Viona Pharmaceuticals Inc. at 1-888-304-5011 or FDA at 1-800-FDA-1088.
USOfficial regulatory label· Warnings and precautions· revised August 1, 2025[2]
WARNINGS
Potentially Fatal Reactions to Sulfonamides:
Fatalities have occurred, although rarely, as a result of severe reactions to sulfonamides (zonisamide is a sulfonamide) including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias.
Such reactions may occur when a sulfonamide is readministered irrespective of the route of administration. If signs of hypersensitivity or other serious reactions occur, discontinue zonisamide immediately. Specific experience with sulfonamide-type adverse reaction to zonisamide is described below.
Serious Skin Reactions Consideration should be given to discontinuing zonisamide in patients who develop an otherwise unexplained rash. If the drug is not discontinued, patients should be observed frequently. , Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)] were reported in the first 11 years of marketing in Japan.
All of the patients were receiving other drugs in addition to zonisamide. In post-marketing experience from Japan, a total of 49 cases of SJS or TEN have been reported, a reporting rate of 46 per million patient-years of exposure. Although this rate is greater than background, it is probably an underestimate of the true incidence because of under-reporting.
, European, or Japanese development programs. S. 2%) zonisamide patients discontinued treatment because of rash compared to none on placebo. S. 4% of patients (12 events per 1,000 patient-years of exposure). 8 events per 1,000 patient years).
S. and European studies and 90% reported within two weeks in the Japanese studies. There was no apparent relationship of dose to the occurrence of rash. Serious Hematologic Events Two confirmed cases of aplastic anemia and one confirmed case of agranulocytosis were reported in the first 11 years of marketing in Japan, rates greater than generally accepted background rates.
, European, or Japanese development programs. There is inadequate information to assess the relationship, if any, between dose and duration of treatment and these events. Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multi-Organ Hypersensitivity Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as multi-organ hypersensitivity, has occurred with zonisamide.
This is not medical advice. Consult a qualified healthcare professional.
Who should not take it
USOfficial regulatory label· Contraindications· revised August 1, 2025[2]
CONTRAINDICATIONS
Zonisamide capsules are contraindicated in patients who have demonstrated hypersensitivity to sulfonamides or zonisamide.
This is not medical advice. Consult a qualified healthcare professional.
Posology - adults 3 Dosage escalation and maintenance Zonisamide Viatris may be taken as monotherapy or added to existing therapy in adults. The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 1.
Some patients, especially those not taking CYP3A4-inducing agents, may respond to lower doses. 4). In clinical studies of adult patients, dose reductions of 100 mg at weekly intervals have been used with concurrent adjustment of other antiepileptic medicine doses (where necessary).
If a higher dose is required: increase at two-weekly intervals in increments of 100 mg up to a maximum of 500 mg. 5) Week 1 Week 2 Week 3 to 5 300 to 500 mg per day (once a day or two divided doses). 50 mg/day (in two divided doses) 100 mg/day (in two divided doses) Increase at weekly intervals in increments of 100 mg - without CYP3A4-inducing agents; or with renal or hepatic impairment Week 1 + 2 Week 3 + 4 Week 5 to 10 300 to 500 mg per day (once a day or two divided doses).
Some patients may respond to lower doses. 50 mg/day (in two divided doses) 100 mg/day (in two divided doses) Increase at two- weekly intervals in increments of up to 100 mg General dosing recommendations for Zonisamide Viatris in special patient populations Paediatric population (aged 6 years and above) Dosage escalation and maintenance Zonisamide Viatris must be added to existing therapy for paediatric patients aged 6 years and above.
The dose should be titrated on the basis of clinical effect. Recommended escalation and maintenance doses are given in Table 2. Some patients, especially those not taking CYP3A4-inducing agents, may respond to lower doses. 4: Paediatric Population).
4 Table 2. 5) Week 1 Weeks 2 to 8 Patients of weight 20 to 55 kga Patients of weight > 55 kg 1 mg/kg/day (once a day) Increase at weekly intervals in increments of 1 mg/kg 6 to 8 mg/kg/day (once a day) 300 – 500 mg/day (once a day) - without CYP3A4-inducing agents Week 1 + 2 Weeks ≥ 3 6 to 8 mg/kg/day (once a day) 300 – 500 mg/day (once a day) 1 mg/kg/day (once a day) Increase at two- weekly intervals in increments of 1 mg/kg Note: a.
To ensure a therapeutic dose is maintained the weight of a child should be monitored and the dose reviewed as weight changes occur up to a weight of 55 kg. The dose regime is 6-8 mg/kg/day up to a maximum dose of 500 mg/day. The safety and efficacy of zonisamide in children aged below 6 years or those below 20 kg have not yet been established.
There are limited data from clinical studies in patients with a body weight of less than 20 kg. Therefore children aged 6 years and above and with a body weight less than 20 kg should be treated with caution. It is not always possible to precisely achieve the calculated dose with the commercially available capsule strengths of zonisamide.
In these cases it is therefore recommended that the zonisamide total dose should be rounded up or down to the nearest available dose that can be achieved with commercially available capsule strengths of zonisamide (25 mg, 50 mg and 100 mg).
4). e. in accordance with the schedule in Table 3). Table 3. Paediatric population (aged 6 years and above) – recommended down-titration schedule Weight Decrease at weekly intervals in increments of: 20 – 28 kg 25 to 50 mg / day* 29 – 41 kg 50 to 75 mg / day* 42 – 55 kg 100 mg / day* >55 kg 100 mg / day* Note: * All doses are once daily.
Elderly Caution should be exercised at initiation of treatment in elderly patients as there is limited information on the use of zonisamide in these patients. 8). 5 Renal impairment Caution must be exercised in treating patients with renal impairment, as there is limited information on use in such patients and a slower titration of Zonisamide Viatris might be required.
Since zonisamide and its metabolites are excreted renally, it should be discontinued in patients who develop acute renal failure or where a clinically significant sustained increase in serum creatinine is observed. In subjects with renal impairment, renal clearance of single doses of zonisamide was positively correlated with creatinine clearance.
The plasma AUC of zonisamide was increased by 35% in subjects with creatinine clearance < 20 ml/min. Hepatic impairment Use in patients with hepatic impairment has not been studied. Therefore use in patients with severe hepatic impairment is not recommended.
Caution must be exercised in treating patients with mild to moderate hepatic impairment, and a slower titration of Zonisamide Viatris may be required. Method of administration Zonisamide Viatris hard capsules are for oral use. 2).
This is not medical advice. Consult a qualified healthcare professional.
Side effects & warnings
EUOfficial regulatory label· Adverse reactions· revised October 22, 2025[3]
Summary of the safety profile Zonisamide has been administered to over 1,200 patients in clinical studies, more than 400 of whom received zonisamide for at least 1 year. In addition there has been extensive post-marketing experience with zonisamide in Japan since 1989 and in the USA since 2000.
It should be noted that zonisamide is a benzisoxazole derivative, which contains a sulfonamide group. 4). The most common adverse reactions in controlled adjunctive-therapy studies were somnolence, dizziness and anorexia. The most common adverse reactions in a randomised, controlled monotherapy trial comparing zonisamide with carbamazepine prolonged release were decreased bicarbonate, decreased appetite, and decreased weight.
8%. 7%. Tabulated list of adverse reactions Adverse reactions associated with zonisamide obtained from clinical studies and post-marketing surveillance are tabulated below. The frequencies are arranged according to the following scheme: very common ≥ 1/10 common ≥ 1/100 to < 1/10 uncommon ≥ 1/1,000 to < 1/100 rare ≥ 1/10,000 to < 1/1,000 very rare < 1/10,000 not known cannot be estimated from the available data Table 4.
Adverse reactions associated with zonisamide obtained from adjunctive use clinical studies and post-marketing surveillance System Organ Class (MedDRA terminology) Very Common Common Uncommon Very Rare Infections and infestation Pneumonia Urinary tract infection Blood and lymphatic system disorders Ecchymosis Agranulocytosis Aplastic anaemia Leucocytosis Leucopoenia Lymphadenopathy Pancytopenia, Thrombocytopenia Immune system disorders Hypersensitivity Drug-induced hypersensitivity syndrome Drug rash with eosinophilia and systemic symptoms Metabolism and nutrition disorders Anorexia Hypokalaemia Metabolic acidosis Renal tubular acidosis Psychiatric Disorders Agitation Irritability Confusional state Depression Affect lability Anxiety Insomnia Psychotic disorder Anger Aggression Suicidal ideation Suicide attempt Hallucination Nervous system disorders Ataxia Dizziness Memory impairment Somnolence Bradyphrenia Disturbance in attention Nystagmus Paraesthesia Speech disorder Tremor Convulsion Amnesia Coma Grand mal seizure Myasthenic syndrome Neuroleptic malignant syndrome Status epilepticus 13 System Organ Class (MedDRA terminology) Very Common Common Uncommon Very Rare Eye disorders Diplopia Angle closure glaucoma Eye pain Myopia Vision blurred Visual acuity reduced Respiratory, thoracic and mediastinal disorders Dyspnoea Pneumonia aspiration Respiratory disorder Hypersensitivity-type Pneumonitis Gastrointestinal disorders Abdominal pain Constipation Diarrhoea Dyspepsia Nausea Vomiting Pancreatitis Hepatobiliary disorders Cholecystitis Cholelithiasis Hepatocellular damage Skin and subcutaneous tissue disorders Rash Pruritus Alopecia Anhidrosis Erythema multiforme Stevens-Johnson syndrome Toxic epidermal necrolysis Musculoskeletal and connective tissue disorders Rhabdomyolysis Renal and urinary disorders Nephrolithiasis Calculus urinary Hydronephrosis Renal failure Urine abnormality General disorders and administration site conditions Fatigue Influenza-like illness Pyrexia Oedema peripheral Investigations Decreased bicarbonate Weight decreased Blood creatine phosphokinase increased Blood creatinine increased Blood urea increased Liver function tests abnormal Injury, poisoning and procedural complications Heat stroke In addition there have been isolated cases of Sudden Unexplained Death in Epilepsy Patients (SUDEP) receiving zonisamide.
Table
EUOfficial regulatory label· Warnings and precautions· revised October 22, 2025[3]
Unexplained rash Serious rashes occur in association with zonisamide therapy, including cases of Stevens-Johnson syndrome. Consideration must be given to discontinuing zonisamide in patients who develop an otherwise unexplained rash.
All patients who develop a rash while taking zonisamide must be closely supervised, with additional levels of caution applied to those patients receiving concomitant antiepileptic agents that may independently induce skin rashes. Withdrawal seizures In accordance with current clinical practice, discontinuation of zonisamide in patients with epilepsy must be accomplished by gradual dose reduction, to reduce the possibility of seizures on withdrawal.
There are insufficient data for the withdrawal of concomitant antiepileptic medicines once seizure control with zonisamide has been achieved in the add-on situation, in order to reach monotherapy with zonisamide. Therefore, withdrawal of concomitant anti-epileptic medicinal products must be undertaken with caution.
Sulfonamide reactions Zonisamide is a benzisoxazole derivative, which contains a sulfonamide group. Serious immune based adverse reactions that are associated with medicinal products containing a sulfonamide group include rash, allergic reaction and major haematological disturbances, including aplastic anaemia, which very rarely can be fatal.
Cases of agranulocytosis, thrombocytopenia, leucopenia, aplastic anaemia, pancytopenia and leucocytosis have been reported. There is inadequate information to assess the relationship, if any, between dose and duration of treatment and these events.
Acute myopia and secondary angle closure glaucoma A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in adult and paediatric patients receiving zonisamide. Symptoms include acute onset of 6 decreased visual acuity and/or ocular pain.
Ophthalmologic findings can include myopia, anterior chamber shallowing, and ocular hyperaemia (redness) and increased intraocular pressure. This syndrome may be associated with supraciliary effusion resulting in anterior displacement of the lens and iris, with secondary angle closure glaucoma.
Symptoms may occur within hours to weeks of initiating therapy. Treatment includes discontinuation of zonisamide, as rapidly as possible in the judgment of the treating physician, and appropriate measures to reduce intraocular pressure.
This is not medical advice. Consult a qualified healthcare professional.
Who should not take it
EUOfficial regulatory label· Contraindications· revised October 22, 2025[3]
1 or to sulfonamides.
This is not medical advice. Consult a qualified healthcare professional.
Symptoms may occur within hours to weeks of initiating therapy. Treatment includes discontinuation of zonisamide, as rapidly as possible in the judgment of the treating physician, and appropriate measures to reduce intraocular pressure.
Elevated intraocular pressure of any aetiology, if left untreated, can lead to serious sequelae including permanent vision loss. Caution should be used when treating patients with history of eye disorders with zonisamide. Suicide ideation and behaviour Suicidal ideation and behaviour have been reported in patients treated with anti- epileptic agents in several indications.
A meta-analysis of randomised placebo- controlled trials of anti-epileptic medicinal products has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for zonisamide.
Therefore patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.
Kidney stones Some patients, especially those with a predisposition to nephrolithiasis, may be at increased risk for renal stone formation and associated signs and symptoms such as renal colic, renal pain or flank pain. Nephrolithiasis may lead to chronic kidney damage.
Risk factors for nephrolithiasis include prior stone formation, a family history of nephrolithiasis and hypercalciuria. None of these risk factors can reliably predict stone formation during zonisamide treatment. In addition, patients taking other medications associated with nephrolithiasis may be at increased risk.
Increasing fluid intake and urine output may help reduce the risk of stone formation, particularly in those with predisposing risk factors. e. decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis) is associated with zonisamide treatment.
This metabolic acidosis is caused by renal bicarbonate loss due to the inhibitory effect of zonisamide on carbonic anhydrase. Such electrolyte imbalance has been observed with the use of zonisamide in placebo-controlled clinical trials and in the post-marketing period.
Generally, zonisamide-induced metabolic acidosis occurs early in treatment although cases can occur at any time during treatment. 5 mEq/l at daily doses of 300 mg in adults); rarely patients can experience more severe decreases. Conditions or therapies that predispose to acidosis (such as renal disease, severe respiratory disorders, status epilepticus, diarrhoea, surgery, ketogenic diet, or medicinal products) may be additive to the bicarbonate lowering effects of zonisamide.
The risk of zonisamide induced metabolic acidosis appears to be more frequent and severe in younger patients. Appropriate evaluation and monitoring of serum bicarbonate levels should be carried out in patients taking zonisamide who have underlying conditions which might increase the risk of acidosis, in patients who are at an increased risk of adverse consequences of metabolic acidosis and in patients with symptoms suggestive of metabolic acidosis.
If metabolic acidosis develops and persists, consideration should be given to reducing the dose or discontinuing Zonisamide Teva (by gradual discontinuation or reduction of a therapeutic dose) as osteopenia may develop. If the decision is made to continue patients on Zonisamide Teva in the face of persistent acidosis, alkali […]
Some of these events have been fatal or life-threatening. DRESS typically, although not exclusively, presents with fever, rash, lymphadenopathy and/or facial swelling, in association with other organ system involvement, such as hepatitis, nephritis, hematologic abnormalities, myocarditis, or myositis, sometimes resembling an acute viral infection.
Eosinophilia is often present. This disorder is variable in its expression, and other organ systems not noted here may be involved. , fever, lymphadenopathy) may be present even though rash is not evident. If such signs or symptoms are present, the patient should be evaluated immediately.
Zonisamide should be discontinued if an alternative etiology for the signs or symptoms cannot be established. Oligohidrosis and Hyperthermia in Pediatric Patients Oligohidrosis, sometimes resulting in heat stroke and hospitalization, is seen in association with zonisamide in pediatric patients.
During the pre-approval development program in Japan, one case of oligohidrosis was reported in 403 pediatric patients, an incidence of 1 case per 285 patient - years of exposure. S. or European development programs, fewer than 100 pediatric patients participated in these trials.
In the first 11 years of marketing in Japan, 38 cases were reported, an estimated reporting rate of about 1 case per 10,000 patient-years of exposure. , 2 cases were reported, an estimated reporting rate of about 12 cases per 10,000 patient-years of exposure.
These rates are underestimates of the true incidence because of under-reporting. S. Decreased sweating and an elevation in body temperature above normal characterized these cases. Many cases were reported after exposure to elevated environmental temperatures.
Heat stroke, requiring hospitalization, was diagnosed in some cases. There have been no reported deaths. Pediatric patients appear to be at an increased risk for zonisamide-associated oligohidrosis and hyperthermia. Patients, especially pediatric patients, treated with zonisamide should be monitored closely for evidence of decreased sweating and increased body temperature, especially in warm or hot weather.
Caution should be used when zonisamide is prescribed with other drugs that predispose patients to heat-related disorders; these drugs include, but are not limited to, carbonic anhydrase inhibitors and drugs with anticholinergic activity.
The practitioner should be aware that the safety and effectiveness of zonisamide in pediatric patients have not been established, and that zonisamide is not approved for use in pediatric patients. Acute Myopia and Secondary Angle Closure Glaucoma Acute myopia and secondary angle closure glaucoma have been reported in patients receiving zonisamide.
Elevated intraocular pressure can lead to serious sequelae, including permanent vision loss, if left untreated. Symptoms in reported cases have included acute onset of decreased visual acuity and/or ocular pain. Ophthalmologic findings can include myopia, anterior chamber shallowing, ocular hyperemia (redness), and increased intraocular pressure.
Mydriasis may or may not be present. This syndrome may be associated with ciliochoroidal effusion resulting in anterior displacement of the lens and iris, with secondary angle closure glaucoma. Symptoms typically occur within one month after initiating zonisamide therapy.
In contrast to primary narrow angle glaucoma, which is rare under 40 years of age, secondary angle closure glaucoma associated with zonisamide has been reported both in pediatric patients and in adults. The primary treatment to reverse symptoms is discontinuation of zonisamide as rapidly as possible, according to the judgment of the treating physician.
Other therapeutic measures, in conjunction with discontinuation of zonisamide, may be helpful. Myopia and secondary angle closure glaucoma usually resolve or improve after discontinuation of zonisamide. Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including zonisamide, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.
Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. 7) of suicidal thinking or behavior compared to patients randomized to placebo.
24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide.
The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication.
The risk did not vary substantially by age (5 years to 100 years) in the clinical trials analyzed. Table 3 shows absolute and relative risk by indication for all evaluated AEDs. 9 The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications.
Anyone considering prescribing zonisamide or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior.
Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated. Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm.
Behaviors of concern should be reported immediately to healthcare providers (see WARNINGS, Cognitive/Neuropsychiatric Adverse Events subsection below). , decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis) (see PRECAUTIONS , Laboratory Tests subsection).
This metabolic acidosis is caused by renal bicarbonate loss due to the inhibitory effect of zonisamide on carbonic anhydrase. Generally, zonisamide-induced metabolic acidosis occurs early in treatment, but it can develop at any time during treatment.
Metabolic acidosis generally appears to be dose-dependent and can occur at doses as low as 25 mg daily. Conditions or therapies that predispose to acidosis (such as renal disease, severe respiratory disorders, status epilepticus, diarrhea, ketogenic diet, or specific drugs) may be additive to the bicarbonate lowering effects of zonisamide.
Some manifestations of acute or chronic metabolic acidosis include hyperventilation, nonspecific symptoms such as fatigue and anorexia, or more severe sequelae including cardiac arrhythmias or stupor. Chronic, untreated, metabolic acidosis may increase the risk for nephrolithiasis or nephrocalcinosis.
Nephrolithiasis has been observed in the clinical development program in 4 % of adults treated with zonisamide, has also been detected by renal ultrasound in 8 % of pediatric treated patients who had at least one ultrasound prospectively collected, and was reported as an adverse event in 3 % (4/133) of pediatric patients (see PRECAUTIONS , Kidney Stones subsection).
Metabolic acidosis can also increase the risk for hyperammonemia, particularly in the presence of drugs which can cause hyperammonemia. Chronic, untreated metabolic acidosis may result in osteomalacia (referred to as rickets in pediatric patients) and/or osteoporosis with an increased risk for fracture.
Of potential relevance, zonisamide treatment was associated with reductions in serum phosphorus and increases in serum alkaline phosphatase, changes that may be related to metabolic acidosis and osteomalacia (see PRECAUTIONS , Laboratory Tests subsection).
Chronic, untreated metabolic acidosis in pediatric patients may reduce growth rates. A reduction in growth rate may eventually decrease the maximal height achieved. The effect of zonisamide on growth and bone-related sequelae has not been systematically investigated.
Measurement of baseline and periodic serum bicarbonate during treatment is recommended. If metabolic acidosis develops and persists, consideration should be given to reducing the dose or discontinuing zonisamide (using dose tapering).
If the decision is made to continue patients on zonisamide in the face of persistent acidosis, alkali treatment should be considered. Serum bicarbonate was not measured in the adjunctive controlled trials of adults with epilepsy. However, serum bicarbonate was studied in three clinical trials for indications which have not been approved: a placebo-controlled trial for migraine prophylaxis in adults, a controlled trial for monotherapy in epilepsy in adults, and an open label trial for adjunctive treatment of epilepsy in pediatric patients (3 years to 16 years).
In adults, mean serum bicarbonate reductions ranged from approximately 2 mEq/L at daily doses of 100 mg to nearly 4 mEq/L at daily doses of 300 mg. In pediatric patients, mean serum bicarbonate reductions ranged from approximately 2 mEq/L at daily doses from above 100 mg up to 300 mg, to nearly 4 mEq/L at daily doses from above 400 mg up to 600 mg.
In two controlled studies in adults, the incidence of a persistent treatment-emergent decrease in serum bicarbonate to less than 20 mEq/L (observed at 2 or more consecutive visits or the final visit) was dose-related at relatively low zonisamide doses.
In the monotherapy trial of epilepsy, the incidence of a persistent treatment-emergent decrease in serum bicarbonate was 21% for daily zonisamide doses of 25 mg or 100 mg, and was 43% at a daily dose of 300 mg. In a placebo-controlled trial for prophylaxis of migraine, the incidence of a persistent treatment-emergent decrease in serum bicarbonate was 7% for placebo, 29% for 150 mg daily, and 34% for 300 mg daily.
The incidence of persistent markedly abnormally low serum bicarbonate (decrease to less than 17 mEq/L and more than 5 mEq/L from a pretreatment value of at least 20 mEq/L) in these controlled trials was 2% or less. In the pediatric study, the incidence of persistent, treatment-emergent decreases in serum bicarbonate to levels less than 20 mEq/L was 52% at doses up to 100 mg daily, was 90% for a wide range of doses up to 600 mg daily, and generally appeared to increase with higher doses.
The incidence of a persistent markedly abnormally low serum bicarbonate value was 4 % at doses up to 100 mg daily, was 18% for a wide range of doses up to 600 mg daily, and generally appeared to increase with higher doses. Some patients experienced moderately severe serum bicarbonate decrements down to a level as low as 10 mEq/L.
The relatively high frequencies of varying severities of metabolic acidosis observed in this study of pediatric patients (compared to the frequency and severity observed in various clinical trial development programs in adults) suggest that pediatric patients may be more likely to develop metabolic acidosis than adults.
Seizures on Withdrawal As with other AEDs, abrupt withdrawal of zonisamide in patients with epilepsy may precipitate increased seizure frequency or status epilepticus. Dose reduction or discontinuation of zonisamide should be done gradually.
Teratogenicity Women of child bearing potential who are given zonisamide should be advised to use effective contraception. Zonisamide was teratogenic in mice, rats, and dogs and embryolethal in monkeys when administered during the period of organogenesis.
A variety of fetal abnormalities, including cardiovascular defects, and embryo-fetal deaths occurred at maternal plasma levels similar to or lower than therapeutic levels in humans. These findings suggest that the use of zonisamide during pregnancy in humans may present a significant risk to the fetus (see PRECAUTIONS, Pregnancy subsection ).
Zonisamide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Cognitive/ Neuropsychiatric Adverse Events Use of zonisamide was frequently associated with central nervous system-related adverse events.
The most significant of these can be classified into three general categories: 1) psychiatric symptoms, including depression and psychosis, 2) psychomotor slowing, difficulty with concentration, and speech or language problems, in particular, word-finding difficulties, and 3) somnolence or fatigue.
4% of placebo patients. 0% were hospitalized because of reported depression or suicide attempts. 2% of patients discontinued zonisamide or were hospitalized due to psychosis or psychosis-related symptoms compared to none of the placebo patients.
4% were hospitalized because of reported psychosis or related symptoms. Psychomotor slowing and difficulty with concentration occurred in the first month of treatment and were associated with doses above 300 mg/day. Speech and language problems tended to occur after 6 to 10 weeks of treatment and at doses above 300 mg/day.
Although in most cases these events were of mild to moderate severity, they at times led to withdrawal from treatment. Somnolence and fatigue were frequently reported CNS adverse events during clinical trials with zonisamide. 2% of the patients enrolled in controlled trials.
Somnolence and fatigue tended to occur within the first month of treatment. Somnolence and fatigue occurred most frequently at doses of 300 mg/day to 500 mg/day. Patients should be cautioned about this possibility and special care should be taken by patients if they drive, operate machinery, or perform any hazardous task.
Hyperammonemia and Encephalopathy Hyperammonemia and encephalopathy have been reported with the postmarketing use of zonisamide. Zonisamide treatment inhibits carbonic anhydrase activity, which may cause metabolic acidosis that is associated with an increased risk for developing hyperammonemia.
Hyperammonemia resulting from zonisamide can also be asymptomatic. The risks of hyperammonemia and various manifestations of encephalopathy may be increased in patients treated with zonisamide and concomitantly taking other medications that can cause hyperammonemia, including valproic acid or topiramate (see PRECAUTIONS ).
Patients with inborn errors of metabolism or reduced hepatic mitochondrial activity may be at an increased risk for hyperammonemia with or without encephalopathy and this risk may be increased by zonisamide use. , unexplained change in mental status, vomiting, or lethargy) of encephalopathy occur.
Hyperammonemia resulting from zonisamide resolves when zonisamide is discontinued. Hyperammonemia from zonisamide may resolve or decrease in severity with a decrease of the daily dose.
Elevated intraocular pressure of any aetiology, if left untreated, can lead to serious sequelae including permanent vision loss. Caution should be used when treating patients with history of eye disorders with zonisamide. Suicide ideation and behaviour Suicidal ideation and behaviour have been reported in patients treated with anti-epileptic agents in several indications.
A meta-analysis of randomised placebo-controlled trials of anti-epileptic medicinal products has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for zonisamide.
Therefore, patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.
Kidney stones Some patients, especially those with a predisposition to nephrolithiasis, may be at increased risk for renal stone formation and associated signs and symptoms such as renal colic, renal pain or flank pain. Nephrolithiasis may lead to chronic kidney damage.
Risk factors for nephrolithiasis include prior stone formation, a family history of nephrolithiasis and hypercalciuria. None of these risk factors can reliably predict stone formation during zonisamide treatment. In addition, patients taking other medications associated with nephrolithiasis may be at increased risk.
Increasing fluid intake and urine output may help reduce the risk of stone formation, particularly in those with predisposing risk factors. e. decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis) is associated with zonisamide treatment.
This metabolic acidosis is caused by renal bicarbonate loss due to the inhibitory effect of zonisamide on carbonic anhydrase. Such electrolyte imbalance has been observed with the use of zonisamide in placebo-controlled clinical trials and in the post-marketing period.
Generally, zonisamide-induced metabolic acidosis occurs early in treatment although cases can occur at any time during treatment. 5 mEq/l at daily doses of 300 mg in adults); rarely patients can experience more severe decreases. Conditions or therapies that predispose to acidosis (such as renal disease, severe respiratory disorders, status epilepticus, diarrhoea, surgery, ketogenic diet, or medicinal products) may be additive to the bicarbonate lowering effects of zonisamide.
The risk of zonisamide induced metabolic acidosis appears to be more frequent and severe in younger patients. Appropriate evaluation and monitoring of serum bicarbonate levels should be carried out in patients taking zonisamide who have underlying conditions which might increase the risk of acidosis, in patients who are at an increased risk of adverse consequences of metabolic acidosis and in patients with symptoms suggestive of metabolic acidosis.
If metabolic acidosis develops and persists, consideration should be given to reducing the dose or discontinuing zonisamide (by gradual discontinuation or reduction of a therapeutic dose) as osteopenia may develop. If the decision is made to continue patients on zonisamide in the face of persistent acidosis, alkali treatment should be considered.