Skip to main content

Zonisamide Side Effects

Medically reviewed by Last updated on Sep 17, 2023.

Applies to zonisamide: oral capsule, oral suspension.

Serious side effects of Zonisamide

Along with its needed effects, zonisamide may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking zonisamide:

More common

Less common


Incidence not known

Other side effects of Zonisamide

Some side effects of zonisamide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to zonisamide: oral capsule, oral suspension.


The most common adverse reactions to this drug are somnolence, dizziness, and anorexia.[Ref]


Very common (10% or more): Anorexia (13%)

Common (1% to 10%): Abdominal pain, nausea, diarrhea, dyspepsia, constipation, dry mouth[Ref]

Nervous system

Very common (10% or more): Somnolence (17%), dizziness (13%), headache (10%), ataxia

Common (1% to 10%): Paresthesia, fatigue, tiredness, bradyphrenia, tremor

Uncommon (0.1% to 1%): Convulsion

Very rare (less than 0.01%): Coma, grand mal seizure, myasthenic syndrome, neuroleptic malignant syndrome, status epilepticus

Postmarketing reports: Restless legs syndrome[Ref]


Common (1% to 10%): Speech abnormalities, difficulties in verbal expression, taste perversion[Ref]


Very common (10% or more): Agitation, irritability, confusional state, depression

Common (1% to 10%): Difficulty concentrating, difficulty with memory, mental slowing, insomnia, anxiety, nervousness, affect lability, psychotic disorder

Uncommon (0.1% to 1%): Anger, aggression, suicidal ideation, suicide attempt

Very rare (less than 0.01%): Hallucination, amnesia, mania[Ref]


Common (1% to 10%): Nystagmus, diplopia[Ref]


Common (1% to 10%): Rash

Very rare (less than 0.01%): Drug rash with eosinophilia and systemic symptoms, anhidrosis, erythema multiforme, pruritus, Stevens-Johnson syndrome, toxic epidermal necrolysis[Ref]


Very common (10% or more): Anorexia

Common (1% to 10%): Weight loss

Very rare (less than 0.01%): Metabolic acidosis

Postmarketing reports: Elevated creatine phosphokinase[Ref]


Common (1% to 10%): Ecchymosis

Very rare (less than 0.01%): Agranulocytosis, aplastic anemia, leukocytosis, leucopenia, lymphadenopathy, pancytopenia, thrombocytopenia[Ref]


Common (1% to 10%): Rhinitis

Uncommon (0.1% to 1%): Pneumonia[Ref]


Uncommon (0.1% to 1%): Urinary tract infection

Postmarketing reports: Acute pancreatitis[Ref]


Postmarketing reports: Rhabdomyolysis[Ref]


Uncommon (0.1% to 1%): Urinary tract infection[Ref]


Common (1% to 10%): Hypersensitivity

Very rare (less than 0.01%): Drug induced hypersensitivity syndrome[Ref]


Common (1% to 10%): Influenza syndrome[Ref]


Very rare (less than 0.01%): Renal tubular acidosis

Frequency not reported: Nephrolithiasis, hydronephrosis, renal failure, urine abnormality[Ref]


1. Product Information. Zonegran (zonisamide). Elan Pharmaceuticals. 2001;PROD.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Pharmaceutical Society of Australia. APPGuide online. Australian prescription products guide online. 2006.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.