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Primidone Side Effects

For the Consumer

Applies to primidone: oral suspension, oral tablet

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)
  • 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

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


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. "Product Information. Primidone (primidone)." Amneal Pharmaceuticals, Glasgow, KY.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

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

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.