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Methsuximide Side Effects

Medically reviewed by Last updated on Aug 1, 2022.

Applies to methsuximide: oral capsule.

Serious side effects of Methsuximide

Along with its needed effects, methsuximide 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:


  • Attempts at killing oneself
  • feeling that others are watching you or controlling your behavior
  • feeling that others can hear your thoughts
  • feeling, seeing, or hearing things that are not there
  • severe mood or mental changes
  • unusual behavior

Incidence not known

  • Attack, assault, or force
  • blistering, peeling, or loosening of the skin
  • blood in the urine
  • bloody, black, or tarry stools
  • chest pain
  • chills
  • cloudy urine
  • cough or hoarseness
  • diarrhea
  • discouragement
  • feeling sad or empty
  • fever
  • high fever
  • irritability
  • itching
  • joint or muscle pain
  • lack of appetite
  • loss of interest or pleasure
  • lower back or side pain
  • mood or mental changes
  • nervousness
  • painful or difficult urination
  • pale skin
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • shakiness and unsteady walk
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swelling around the eyes
  • swollen glands
  • tiredness
  • trouble with concentrating
  • trouble with sleeping
  • unexplained bleeding or bruising
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vision changes

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

Symptoms of overdose

  • Change in consciousness
  • difficult or troubled breathing
  • irregular, fast or slow, or shallow breathing
  • loss of consciousness
  • pale or blue lips, fingernails, or skin

Other side effects of Methsuximide

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.