Skip to main content

Ethosuximide Side Effects

Medically reviewed by Last updated on Sep 27, 2023.

Applies to ethosuximide: oral capsule liquid filled, oral syrup.

Serious side effects of Ethosuximide

Along with its needed effects, ethosuximide may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking ethosuximide:


Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur while taking ethosuximide:

Symptoms of overdose

Other side effects of Ethosuximide

Some side effects of ethosuximide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:


Incidence not known

For Healthcare Professionals

Applies to ethosuximide: oral capsule, oral syrup.


The more commonly reported adverse reactions have included gastrointestinal symptoms such as anorexia, vague gastric upset, nausea and vomiting, and abdominal pain.


Frequency not reported: Anorexia, vague gastric upset, nausea, vomiting, cramps, epigastric and abdominal pain, weight loss, gum hypertrophy, diarrhea, swollen tongue, hiccups[Ref]


Frequency not reported: Urticaria, Stevens-Johnson syndrome (SJS), pruritic erythematous rashes, hirsutism, Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), systemic lupus erythematosus[Ref]


Frequency not reported: Leukopenia, agranulocytosis, pancytopenia (with or without bone marrow suppression), eosinophilia, drug-induced immune thrombocytopenia[Ref]

Nervous system

Frequency not reported: Drowsiness, headache, dizziness, lethargy, fatigue, ataxia[Ref]


Rare (less than 0.1%): Paranoid psychosis, increased libido, increased state of depression with overt suicidal intentions

Frequency not reported: Disturbances, night terrors, inability to concentrate, aggressiveness, euphoria, irritability, hyperactivity[Ref]


Frequency not reported: Myopia[Ref]


Frequency not reported: Vaginal bleeding, microscopic hematuria[Ref]


Frequency not reported: Allergic reaction


1. (2001) "Product Information. Zarontin (ethosuximide)." Parke-Davis

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.