Skip to main content

Celontin Side Effects

Generic name: methsuximide

Medically reviewed by Last updated on Jan 9, 2024.

Note: This document contains side effect information about methsuximide. Some dosage forms listed on this page may not apply to the brand name Celontin.

Applies to methsuximide: oral capsule.

Serious side effects of Celontin

Along with its needed effects, methsuximide (the active ingredient contained in Celontin) 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 methsuximide:


Incidence not known

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

Symptoms of overdose

Other side effects of Celontin

Some side effects of methsuximide 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 methsuximide: oral capsule.


The more frequently reported adverse events have included gastrointestinal symptoms such as nausea, vomiting, and anorexia and neurologic reactions such as drowsiness, dizziness and headache.


Frequency not reported: Nausea, vomiting, anorexia, diarrhea, weight loss, epigastric and abdominal pain, constipation, hiccups[Ref]

Nervous system

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


Rare (less than 0.1%): Psychosis, suicidal behavior, auditory hallucinations

Frequency not reported: Confusion, instability, mental slowness, depression, hypochondriacal behavior, aggressiveness, irritability, nervousness, insomnia.[Ref]


Frequency not reported: Eosinophilia, leukopenia, monocytosis, and pancytopenia with or without bone marrow suppression[Ref]


Frequency not reported: Periorbital edema, blurred vision[Ref]


Frequency not reported: Proteinuria, microscopic hematuria[Ref]


Frequency not reported: Hyperemia[Ref]


Frequency not reported: Urticaria, Stevens-Johnson syndrome, pruritic erythematous rashes[Ref]


1. Product Information. Celontin (methsuximide). 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.