Drug side effects
ethosuximide Side Effects
The reactions most often reported to the FDA for ethosuximide (also sold as Zarontin), with demographics, serious outcomes, and reporting trends.
Data updated 2026-05-15
- 2,415
- FAERS reports
Data from the FDA Adverse Event Reporting System (FAERS), 2004 to 2025. A FAERS report records a temporal association, not proof of cause. See our methodology for how figures are compiled and de-duplicated.
The most commonly reported side effects of ethosuximide come from 2,415 reports to the FDA, broken down here by frequency, patient demographics, and serious outcomes.
This page analyzes 2,415 reports to the FDA Adverse Event Reporting System (FAERS) for ethosuximide (Zarontin): the reactions reported most often, who reported them, serious outcomes such as hospitalization, and year-over-year trends. A FAERS report does not prove the drug caused the effect, and report volume tracks how widely a drug is used, not how likely an effect is for any one person. Educational information, not medical advice.
Total Reports
2,415
Reports Mentioning Death
62
2.6% of reports — not proof the medicine caused the death
Hospitalizations
568
23.5% of reports
Top Indication
Epilepsy
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 62 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| SEIZURE | 13 |
| DEATH | 10 |
| SOMNOLENCE | 10 |
| ABNORMAL WEIGHT GAIN | 9 |
| COLON CANCER | 9 |
| DYSKINESIA | 9 |
| DYSPNOEA | 9 |
| FEELING HOT | 9 |
| GYNAECOMASTIA | 9 |
| HYPERHIDROSIS | 9 |
| POLLAKIURIA | 9 |
| RESPIRATORY FAILURE | 9 |
| HYPOTENSION | 8 |
| INSOMNIA | 8 |
| LUNG NEOPLASM MALIGNANT | 8 |
| RASH PRURITIC | 8 |
| VOMITING | 8 |
| INCREASED APPETITE | 7 |
Reactions in Hospitalization Reports
Top reactions in 568 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| SEIZURE | 92 |
| DRUG INTERACTION | 39 |
| SOMNOLENCE | 38 |
| VOMITING | 38 |
| EPILEPSY | 32 |
| GENERALISED TONIC-CLONIC SEIZURE | 31 |
| STATUS EPILEPTICUS | 29 |
| PETIT MAL EPILEPSY | 28 |
| NAUSEA | 25 |
| PYREXIA | 24 |
| DECREASED APPETITE | 23 |
| DEPRESSED LEVEL OF CONSCIOUSNESS | 22 |
| DIZZINESS | 19 |
| FALL | 19 |
| PNEUMONIA | 19 |
| ATAXIA | 18 |
| CONVULSION | 18 |
Nearby, Related Medications
What the FAERS Data Reveals About ethosuximide Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 2,415 voluntary reports linked to ethosuximide and its brand equivalents (Zarontin), spanning 2004 through 2025. Of those, 62 (2.6%) listed death as an outcome and 568 (23.5%) involved hospitalization. The most common indication reported alongside adverse events was Epilepsy.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 58% were female and 42% male; age distribution skews toward 0-17, with 969 reports in that bracket. The single most reported reaction is seizure with 347 submissions, followed by somnolence and generalised tonic-clonic seizure.
How to read these numbers
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice, speak with a licensed clinician about any side-effect concerns.
Drugs With a Similar FAERS Report Volume
Other medications with a total FDA adverse-event report count closest to ethosuximide's 2,415.
Read our methodology - how this data is sourced, computed, and verified.