Methsuximide: uses, dosing, side effects & brands
Methsuximide is an anti-epileptic agent sold in the U.S. under one brand, for absence epilepsy. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Anti-Epileptic Agent
- Treats
- Absence Epilepsy
- Available as
- Capsule
- Sold as
- Celontin
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How methsuximide is dosed
From the FDA label for Celontin (application NDA010596). Other methsuximide products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Optimum dosage of Celontin must be determined by trial. A suggested dosage schedule is 300 mg per day for the first week. If required, dosage may be increased thereafter at weekly intervals by 300 mg per day for the three weeks following to a daily dosage of 1.2 g. Because therapeutic effect and tolerance vary among patients, therapy with Celontin must be individualized according to the response of each patient. Optimal dosage is that amount of Celontin which is barely sufficient to control seizures so that side effects may be kept to a minimum. Celontin may be administered in combination with other anticonvulsants when other forms of epilepsy coexist with absence (petit mal).
Methsuximide side effects
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.
Who shouldn’t take methsuximide
Methsuximide should not be used in patients with a history of hypersensitivity to succinimides.
Methsuximide drug interactions
Since Celontin (methsuximide) may interact with concurrently administered antiepileptic drugs, periodic serum level determinations of these drugs may be necessary (eg, methsuximide may increase the plasma concentrations of phenytoin and phenobarbital).
Every methsuximide product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Celontin.
What methsuximide pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| 300;mg;PD525 | 300 mg | yellow | capsule | — |
| 228;300mg | 300 mg | yellow | capsule | — |
What people report to the FDA about methsuximide
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 46 reports naming methsuximide, and the FDA flagged 67% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- multiple-drug resistance5 reports
- seizure5 reports
- somnolence5 reports
- nausea4 reports
- thrombocytopenia4 reports
- treatment failure4 reports
- adverse event3 reports
- ataxia3 reports
Read these as a signal, not a rate. A report does not mean methsuximide caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is methsuximide?
Celontin (Methsuximide) is an anti-epileptic agent used to treat Absence Epilepsy.
What kind of drug is methsuximide?
The FDA classifies methsuximide as an anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take methsuximide with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run methsuximide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does methsuximide come in?
Across the brands we track, methsuximide is currently marketed as capsule, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic methsuximide?
We do not currently list a generic-labelled methsuximide product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Methsuximide: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/methsuximide
- MLA
- “Methsuximide: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/methsuximide.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for methsuximide on DailyMed (NIH) ↗.