What the label lists and what reports show
Ethosuximide side effects
Ethosuximide's FDA label lists its adverse reactions in its own words. FAERS holds 2,489 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is seizure (367 reports).
- Generic listed
Check it at the source: the ethosuximide FDA label on DailyMed (effective June 11, 2026, Chartwell Governmental & Specialty RX, LLC.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of ethosuximide oral solution?See “What is the most important information I should know about ethosuximide oral solution?” Ethosuximide oral solution may cause other serious side effects, including: Serious allergic reactions. Call your healthcare provider right away if you have any of these symptoms: skin rash hives sores in your mouth blistering or peeling skin Changes in thinking, mood, or behavior. Some patients may get abnormally suspicious thoughts, hallucinations (seeing or hearing things that are not there), or delusions (false thoughts or beliefs). Grand mal seizures can happen more often or become worse Call your healthcare provider right away, if you have any of the symptoms listed above. […]
Source: FDA drug label, Chartwell Governmental & Specialty RX, LLC., effective June 11, 2026 (SPL set a825265d-ace9-4463-a16d-f6d5e1e31188), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsBody As A Whole: Allergic reaction, Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). Gastrointestinal System: Gastrointestinal symptoms occur frequently and include anorexia, vague gastric upset, nausea and vomiting, cramps, epigastric and abdominal pain, weight loss, and diarrhea. There have been reports of gum hypertrophy and swelling of the tongue. Hemopoietic System: Hemopoietic complications associated with the administration of ethosuximide have included leukopenia, agranulocytosis, pancytopenia, with or without bone marrow suppression, eosinophilia, and thrombocytopenia (see WARNINGS ). Nervous System: Neurologic and sensory reactions reported during therapy with ethosuximide have included drowsiness, headache, dizziness, euphoria, hiccups, irritability, hyperactivity, lethargy, fatigue, and ataxia. …
Source: FDA drug label, Chartwell Governmental & Specialty RX, LLC., effective June 11, 2026 (SPL set a825265d-ace9-4463-a16d-f6d5e1e31188), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,489 reports list ethosuximide among the medicines taken, each a report of something that happened, not proof the medicine caused it; 63 are coded as a death and 581 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 9 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Ethosuximide: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions