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Zonisamide Side Effects

The most commonly reported side effects of zonisamide include seizure, off label use, and fatigue, based on 14,495 FDA adverse event reports from 2004 to 2025. 10.5% of reports found the drug to be ineffective.

Zonisamide side effects

Percentages show how often each reaction appears relative to total reports for zonisamide.

1
Seizure11.0%1,596
2
Drug Ineffective10.5%1,527
3
Off Label Use6.0%868
4
Fatigue4.3%623
5
Somnolence3.9%571
6
Dizziness3.3%478
7
Headache3.1%456
8
Nausea3.1%453
9
Convulsion3.0%439
10
Fall2.9%417
11
Diarrhoea2.4%354
12
Vomiting2.4%343
13
Drug Interaction2.4%341
14
Condition Aggravated2.3%334
15
Epilepsy2.3%334

These are voluntary reports and do not establish that zonisamide caused these reactions.

Report severity

76.3%Serious11,059 reports
31.1%Hospitalizations4,515 reports
6.2%Fatal902 reports

Seriousness is determined by the reporter, not by OpenClaim.

Zonisamide drug interactions

Other drugs that appear in adverse event reports alongside zonisamide. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Levetiracetam18.4%2,667
2
Lamotrigine11.3%1,640
3
Lacosamide9.4%1,361
4
Topiramate7.8%1,128
5
Clobazam7.7%1,113
6
Carbamazepine6.3%913
7
Valproic-acid5.3%767
8
Cannabidiol5.1%739
9
Vigabatrin5.0%730
10
Phenytoin4.7%682
11
Clonazepam4.1%589
12
Valproate-sodium4.0%585
13
Oxcarbazepine3.7%533
14
Phenobarbital-sodium3.5%505
15
Perampanel3.5%504

Taken alongside

1
Levetiracetam11.2%1,622
2
Lamotrigine9.5%1,382
3
Clonazepam8.6%1,243
4
Clobazam7.5%1,091
5
Acetaminophen7.0%1,009
6
Ergocalciferol6.5%944
7
Gabapentin6.3%910
8
Levothyroxine-sodium5.6%818
9
Topiramate5.5%793
10
Lacosamide5.1%737
11
Diazepam5.0%726
12
Omeprazole4.7%679
13
Albuterol4.6%667
14
Aspirin4.6%664
15
Carbamazepine4.3%630

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports zonisamide side effects

49.1% of zonisamide adverse event reports involve female patients and 31.4% involve male patients. The largest age group is adult at 62%. These figures reflect who reports side effects, not underlying risk.

Sex

Female49.1%
Male31.4%
Unknown19.6%

Age group

< 25.3%
2–1112.2%
12–176.5%
18–6461.8%
65+14.2%

What is zonisamide used for

Conditions and purposes for which patients were taking zonisamide when the adverse event was reported.

Abdominal Pain UpperAbnormal BehaviourAcquired Epileptic AphasiaAdjustment Disorder With Mixed Anxiety And Depressed MoodAffective DisorderAggressionAicardi^s SyndromeAlcohol Use DisorderAlexander DiseaseAllodyniaAnaplastic AstrocytomaAnkylosing SpondylitisAnxietyApnoeic AttackAppetite Disorder

Showing 15 of 415 indications

Zonisamide brand names and reporting trend

Zonisamide is sold under the brand name Zonegran.

Brand names

Zonegran11,957

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking zonisamide with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.