Applies to primidone: oral tablet.

Serious side effects of Primidone

Along with its needed effects, primidone 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

• Shakiness and unsteady walk
• unsteadiness, trembling, or other problems with muscle control or coordination

Less common

• Unusual excitement or restlessness (especially in children and in the elderly)

Rare

• Chills
• cough or hoarseness
• fainting spells
• fever and sore throat
• fever with or without chills
• general feeling of tiredness or weakness
• irregular heartbeat
• lower back or side pain
• painful or difficult urination
• pale skin
• shortness of breath
• skin rash
• sores, ulcers, or white spots on the lips or in the mouth
• unusual bleeding or bruising
• unusual tiredness or weakness

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

Symptoms of overdose

• Confusion
• continuous, uncontrolled rolling eye movements
• double vision
• troubled breathing

Other side effects of Primidone

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

• Clumsiness or unsteadiness
• dizziness or lightheadedness
• feeling of constant movement of self or surroundings
• sensation of spinning

Less common

• Decreased sexual ability
• drowsiness
• loss of appetite
• mood or mental changes
• nausea or vomiting

For Healthcare Professionals

Applies to primidone: oral suspension, oral tablet.

Dermatologic

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]

Hematologic

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

Musculoskeletal

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

Ocular

Common (1% to 10%): Visual disturbances

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

Metabolic

Frequency not reported: Anorexia^[Ref]

Psychiatric

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

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

Primidone^[Ref]

Genitourinary

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

Hepatic

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]

Gastrointestinal

Common (1% to 10%): Nausea

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