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Mysoline Side Effects

Generic name: primidone

Medically reviewed by Last updated on Aug 28, 2023.

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

Applies to primidone: oral tablet.

Serious side effects of Mysoline

Along with its needed effects, primidone (the active ingredient contained in Mysoline) 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 primidone:

More common

Less common


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

Symptoms of overdose

Other side effects of Mysoline

Some side effects of primidone 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:

More common

Less common

For Healthcare Professionals

Applies to primidone: oral suspension, oral tablet.


Uncommon (0.1% to 1%): Allergic reactions (e.g., maculopapular, morbilliform, or scarlatiniform)

Rare (0.01% to 0.1%): Exfoliative dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, lupus erythematosus[Ref]


Rare (0.01% to 0.1%): Megaloblastic anemia, blood dyscrasias, granulocytopenia, agranulocytosis, red-cell hypoplasia and aplasia[Ref]


Rare (0.01% to 0.1%): Arthralgia, osteomalacia, Dupuytren's contracture[Ref]


Common (1% to 10%): Visual disturbances

Uncommon (0.1% to 1%): Diplopia, nystagmus[Ref]


Frequency not reported: Anorexia[Ref]


Uncommon (0.1% to 1%): Hyperirritability, emotional disturbances

Rare (0.01% to 0.1%): Personality changes, psychosis



Uncommon (0.1% to 1%): Sexual impotency[Ref]


Rare (0.01% to 0.1%): Elevations in hepatic enzymes (e.g., gamma-glutamyl transferase [gamma GT], alkaline phosphatase)[Ref]

Nervous system

Common (1% to 10%): Drowsiness, listlessness, ataxia, nystagmus, vertigo

Uncommon (0.1% to 1%): Headache, dizziness[Ref]


Common (1% to 10%): Nausea

Uncommon (0.1% to 1%): Vomiting[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics."

2. Cerner Multum, Inc. "Australian Product Information."

3. (2017) "Product Information. Primidone (primidone)." Amneal Pharmaceuticals

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.