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Ethosuximide Side Effects

The most commonly reported side effects of ethosuximide include seizure, off label use, and generalised tonic-clonic seizure, based on 2,462 FDA adverse event reports from 2004 to 2025. 19.1% of reports found the drug to be ineffective.

Ethosuximide side effects

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

1
Drug Ineffective19.1%471
2
Seizure14.4%354
3
Off Label Use9.1%224
4
Generalised Tonic-clonic Seizure5.8%143
5
Somnolence5.5%135
6
Treatment Failure4.6%114
7
Multiple-drug Resistance4.1%101
8
Fatigue4.1%100
9
Drug Interaction3.8%93
10
Epilepsy3.7%92
11
Petit Mal Epilepsy3.5%86
12
Status Epilepticus3.4%84
13
Vomiting3.4%84
14
Condition Aggravated3.2%79
15
Decreased Appetite3.1%77

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

Report severity

80.7%Serious1,988 reports
23.7%Hospitalizations584 reports
2.5%Fatal62 reports

Seriousness is determined by the reporter, not by OpenClaim.

Ethosuximide drug interactions

Other drugs that appear in adverse event reports alongside ethosuximide. 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
Levetiracetam32.3%796
2
Lamotrigine24.2%595
3
Clobazam18.3%451
4
Valproic-acid15.1%372
5
Topiramate14.3%352
6
Valproate-sodium11.5%282
7
Zonisamide10.0%247
8
Clonazepam9.7%240
9
Lacosamide7.7%189
10
Carbamazepine7.1%175
11
Phenytoin6.7%166
12
Perampanel6.3%155
13
Phenobarbital-sodium6.0%147
14
Cannabidiol6.0%147
15
Vigabatrin4.1%102

Taken alongside

1
Lamotrigine10.8%265
2
Clobazam9.8%242
3
Levetiracetam9.3%229
4
Valproic-acid7.6%186
5
Topiramate6.5%159
6
Clonazepam6.5%159
7
Zonisamide4.8%117
8
Phenytoin4.5%112
9
Diazepam4.3%107
10
Carbamazepine4.0%99
11
Valproate-sodium3.9%95
12
Phenobarbital-sodium3.6%89
13
Divalproex-sodium3.2%79
14
Rufinamide2.7%66
15
Cannabidiol2.5%61

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 ethosuximide side effects

48.6% of ethosuximide adverse event reports involve female patients and 35.2% involve male patients. The largest age group is child at 45%. These figures reflect who reports side effects, not underlying risk.

Sex

Female48.6%
Male35.2%
Unknown16.2%

Age group

< 23.0%
2–1145.2%
12–1715.5%
18–6432.5%
65+3.8%

What is ethosuximide used for

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

Abnormal BehaviourAbsence SeizureAcquired Epileptic AphasiaAmnesiaAsthmaAtonic SeizuresAtaxiaAtonic SeizuresBenign Rolandic EpilepsyBlood Pressure MeasurementBreast CancerClonic ConvulsionConvulsionConvulsion ProphylaxisCsws Syndrome

Showing 15 of 93 indications

Ethosuximide brand names and reporting trend

Ethosuximide is sold under the brand name Zarontin.

Brand names

Zarontin2,188

Quarterly reports (20042025)

20052010201520202025

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

Taking ethosuximide with another medication?

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