Mysoline Side Effects

Generic name: primidone

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

Some side effects of Mysoline may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to primidone: oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking primidone (the active ingredient contained in Mysoline) hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any new or worsening symptoms such as: mood or behavior changes, depression, anxiety, or if you feel agitated, hostile, restless, hyperactive (mentally or physically), or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have any of these serious side effects:

• slurred speech;

• loss of balance or coordination;

• easy bruising or bleeding; or

• unusual weakness.

Less serious side effects of primidone may include:

• dizziness, drowsiness, spinning sensation;

• nausea, vomiting, loss of appetite;

• feeling irritable;

• blurred vision;

• mild skin rash; or

• impotence, loss of interest in sex.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.

For Healthcare Professionals

Applies to primidone: oral suspension, oral tablet

Nervous system

Nervous system effects including ataxia and vertigo have been reported most frequently.

Ataxia and vertigo tend to disappear either with continued therapy or with the reduction of the initial dosage.

Gastrointestinal

Gastrointestinal effects including nausea, anorexia, and vomiting have been reported occasionally.

General

General effects including fatigue, hyperirritability, and drowsiness have been reported occasionally.

Psychiatric

Psychiatric effects including emotional disturbances have been reported occasionally. A case of primidone (the active ingredient contained in Mysoline) induced catatonic schizophrenia has also been reported.

Genitourinary

Massive crystalluria has also been rarely been reported following acute overdoses of primidone (the active ingredient contained in Mysoline)

Genitourinary effects including sexual impotency have been reported occasionally. A case of massive crystalluria has been reported in a patient receiving maintenance doses of primidone.

Ocular

Ocular effects including diplopia and nystagmus have been reported occasionally.

Dermatologic

Dermatologic effects including morbilliform skin eruptions have been reported occasionally.

Hematologic

Hematologic effects including granulocytopenia, agranulocytosis, red cell hypoplasia, thrombocytopenia, and aplasia have been reported rarely. The manufacturer has reported that megaloblastic anemia may occur as a rare idiosyncrasy to primidone (the active ingredient contained in Mysoline)

The anemia may respond to folic acid without the necessity to discontinue the primidone. The phenobarbital metabolite of primidone has been reported to have potentiated porphyrias.

Other

Rheumatologic side effects include drug induced lupus, frozen shoulder, and Dupuytren's contractures.

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