Primidone Side Effects

Medically reviewed by Drugs.com. Last updated on Dec 6, 2024.

Applies to primidone: oral tablet.

Precautions

It is very important that your doctor check your progress at regular visits while you are using this medicine to see if it is working properly and to allow for a change in the dose. Blood tests may be needed to check for any unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away. Your doctor may want you to join a pregnancy registry for patients taking a seizure medicine.

If you have been taking primidone regularly for several weeks, you should not suddenly stop taking it without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests (such as the metyrapone and phentolamine tests) may be affected by this medicine.

Before having any kind of surgery, dental treatment, or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for allergies or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; medicine for seizures or barbiturates; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

Primidone may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.

Oral contraceptives (birth control pills) containing estrogen may not work properly if you take them while you are taking primidone. Unplanned pregnancies may occur. You should use a different or additional means of birth control while you are taking primidone. If you have any questions about this, check with your doctor.

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:

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:

For healthcare professionals

Applies to primidone: oral suspension, oral tablet.

Dermatologic adverse events

• 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]

See also:

Further information

Primidone side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer