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Last reviewed on RxList: 11/6/2017
Celontin Side Effects Center

Last reviewed on RxList 11/06/2017

Celontin (methsuximide) is an anti-epileptic (anticonvulsant) medication used alone or in combination with other medications to treat absence seizures (also called "petit mal" seizures). Common side effects of Celontin include:

  • drowsiness
  • dizziness
  • stomach/abdominal pain
  • loss of appetite
  • nausea
  • vomiting
  • weight loss
  • diarrhea
  • constipation
  • headache
  • loss of balance or coordination
  • nervousness
  • confusion, or blurred vision

Dose of Celontin is individualized. A suggested dosage is 300 mg per day for the first week. Dosage may be increased at weekly intervals by 300 mg per day for the three weeks following to a daily dosage of 1.2 g. Celontin may interact with phenobarbital, phenytoin, cold or allergy medicine, sedatives, narcotics, sleeping pills, muscle relaxers, and medicine for depression or anxiety. Tell your doctor all medications and supplements you use. During pregnancy, Celontin should be used only when prescribed. It is unknown if this medication passes into breast milk. Consult your doctor before breastfeeding. Abrupt withdrawal of anticonvulsant medication may precipitate absence (petit mal) status.

Our Celontin (methsuximide) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Celontin Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have a serious side effect such as:

  • signs of infection such as fever, chills, sore throat, flu symptoms, easy bruising or bleeding (nosebleeds, bleeding gums), mouth sores, feeling very weak or tired;
  • signs of liver damage, such as nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • joint pain or swelling with fever, swollen glands, muscle aches, chest pain;
  • patchy skin color, red spots, or a butterfly-shaped skin rash over your cheeks and nose (worsens in sunlight);
  • severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling; or
  • worsening of seizures.

Less serious side effects may include:

  • diarrhea, constipation;
  • stomach pain, nausea, weight loss;
  • dizziness, drowsiness, nervousness, confusion;
  • headache;
  • blurred vision; or
  • loss of balance or coordination.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Celontin (Methsuximide)

Celontin Professional Information


Gastrointestinal System: Gastrointestinal symptoms occur frequently and have included nausea or vomiting, anorexia, diarrhea, weight loss, epigastric and abdominal pain, and constipation.

Hemopoietic System: Hemopoietic complications associated with the administration of methsuximide have included eosinophilia, leukopenia, monocytosis, and pancytopenia with or without bone marrow suppression.

Nervous System: Neurologic and sensory reactions reported during therapy with methsuximide have included drowsiness, ataxia or dizziness, irritability and nervousness, headache, blurred vision, photophobia, hiccups, and insomnia. Drowsiness, ataxia, and dizziness have been the most frequent side effects noted. Psychologic abnormalities have included confusion, instability, mental slowness, depression, hypochondriacal behavior, and aggressiveness. There have been rare reports of psychosis, suicidal behavior, and auditory hallucinations.

Integumentary System: Dermatologic manifestations which have occurred with the administration of methsuximide have included urticaria, Stevens-Johnson syndrome, and pruritic erythematous rashes.

Cardiovascular: Hyperemia.

Genitourinary System: Proteinuria, microscopic hematuria.

Body as a Whole: Periorbital edema.

Read the entire FDA prescribing information for Celontin (Methsuximide)

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© Celontin Patient Information is supplied by Cerner Multum, Inc. and Celontin Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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