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Zonegran Side Effects

Generic Name: zonisamide

Note: This page contains side effects data for the generic drug zonisamide. It is possible that some of the dosage forms included below may not apply to the brand name Zonegran.

For the Consumer

Applies to zonisamide: oral capsule, oral tablet

As well as its needed effects, zonisamide (the active ingredient contained in Zonegran) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking zonisamide, check with your doctor immediately:

More common:
  • Discouragement
  • feeling sad or empty
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • mood or mental changes
  • shakiness or unsteady walking
  • tiredness
  • trouble with concentrating
  • trouble with sleeping
Less common:
  • Agitation
  • bruising
  • delusions
  • hallucinations
  • large, flat blue or purplish patches on the skin
  • rash

If any of the following symptoms of overdose occur while taking zonisamide, get emergency help immediately:

Symptoms of overdose:
  • Difficult or labored breathing
  • faintness
  • loss of consciousness
  • slow or irregular heartbeat

Minor Side Effects

Some zonisamide side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Abdominal or stomach pain
  • anxiety
  • difficulty with memory
  • dizziness
  • double vision
  • headache
  • loss of appetite
  • nausea
  • restlessness
  • sleepiness
  • sleeplessness
  • unusual drowsiness
  • unusual tiredness or weakness
Less common:
  • Aching muscles or joints
  • acid or sour stomach
  • bad, unusual, or unpleasant taste in the mouth
  • belching
  • change in taste
  • chills
  • constipation
  • diarrhea
  • difficulty with speaking
  • difficulty with thinking
  • dry mouth
  • fever
  • general ill feeling
  • headache
  • heartburn
  • indigestion
  • mental slowness
  • nervousness
  • runny or stuffy nose
  • sneezing
  • tingling, burning, or prickly feelings on the skin
  • uncontrolled, back and forth, or rolling eye movements
  • weight loss

For Healthcare Professionals

Applies to zonisamide: oral capsule


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 liability, 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, S. San Francisco, CA.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):

It is possible that some side effects of Zonegran may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.