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Brand Name(s) : Mysoline
Side Effects


Primidone should be used with caution in: the elderly or frail, children, women who are pregnant or who are breastfeeding, liver or kidney problems, breathing problems, or history of alcohol or drug abuse.

It should not be used in: patients with allergy to primidone or to any other ingredient in the medicine, patients with acute porphyria (an inherited blood disorder, causing skinblisters, belly pain and brain or nervous system disorders), or severe liver problems.

Also see list of precautions and interactions.


Store below 25°C.


What is it used for?

  • Primidone is used to treat a number of problems.
  • It is a pyrimidinedione, and is sometimes known as an anticonvulsant.
  • It is used to prevent seizures (fits) and tremors.
  • In general this drug is used to treat all forms of epilepsy except absence seizures (sometimes called petit mal seizures, where the patient may appear to be staring into space with or without jerking or twitching movements of the eye muscles), and it is also used to control essential tremor (a progressive nerve disorder involving tremor of the arms or other part of the body).
  • Benefits of being on this drug can include the prevention of seizures or tremors.

Listed below are the typical uses of primidone.

On occasion your doctor may prescribe this medicine to treat a condition not on the above list.


How often do I take it?

  • Take this medication by mouth, usually once or twice daily. Tablets should be swallowed whole with a drink of water.
  • Use this medication regularly in order to get the most benefit from it.
  • Remember to use it at the same time each day - unless specifically told otherwise by your doctor.
  • It may take some time before the full benefit of this drug takes effect.
  • Certain medical conditions may require different dosage instructions as directed by your doctor.

What dose?

  • Dosage is based on your age, gender, medical condition, response to therapy, and use of certain interacting medicines.

Do I need to avoid anything?

  • Avoid driving or operating machinery if primidone lengthens your reaction time or makes you feel sleepy. Consult your doctor or pharmacist for more details.

When can I stop?

  • It is important to continue taking this medication even if you feel well, unless your doctor tells you to stop.


Only the most common side effects have been listed. If any of these persist or you consider them severe then inform your doctor.

Tell your doctor immediately if you develop any of the following symptoms:

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine (which includes vaccines, herbals and over the counter medicines) that you are taking. It is run by the medicines safety watchdog called the Medicines and Healthcare products Regulatory agency (MHRA). Please report any suspected side effect on the Yellow Card Scheme website.


Before taking primidone, tell your doctor or pharmacist if you are allergic to it; or to anticonvulsants; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: acute porphyria (an inherited blood disorder, causing skin blisters, belly pain and brain or nervous system disorders), or severe liver problems.

Before using this medication, tell your doctor or pharmacist your medical history, especially any of the following: any liver or kidney problems, or history of lung diseases or breathing difficulties.

Before having surgery, tell your doctor or dentist that you are taking this medication.

Does alcohol intake affect this drug?

  • The effects of alcohol can be increased by primidone, so avoid or moderate your intake of alcohol.

The elderly: primidone should be used with caution in the elderly as it may not be metabolised as effectively in this group as they may have poorer kidney function than younger patients.

Pregnancy and breastfeeding - please ensure you read the detailed information below


Primidone should not be taken if you are, or are planning to become pregnant, unless your doctor thinks it is necessary.

It is sensible to limit use of medication during pregnancy whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Primidone should only be taken while breastfeeding if your doctor considers it is necessary. Taking primidone while breastfeeding can make your baby very sleepy, hence your baby may need some extra monitoring.

It is sensible to limit use of medication during breastfeeding whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with them first.

This drug should not be used with the following medications because very serious, possibly fatal interactions may occur:

  • Certain antibiotics e.g. telithromycin
  • St John's wort
  • Certain antifungals e.g. voriconazole
  • Dronedarone
  • Eplerenone

If you are currently using any of these medications, tell your doctor or pharmacist before starting primidone.

Before using this medication, tell your doctor or pharmacist of all prescription and non-prescription/herbal products you may use, especially of:

  • Other anticonvulsants (e.g. valproate or phenytoin)
  • Antibiotics (e.g. chloramphenicol, doxycycline or metronidazole)
  • Antidepressants (selective serotonin reuptake inhibitors [SSRIs] such as paroxetine and tricyclic antidepressants [TCAs] such as amitriptyline)
  • Antipsychotics (e.g. aripiprazole)
  • Antifungals (e.g. posaconazole)
  • Antimalarials (e.g. mefloquine)
  • Antivirals (e.g. indinavir, lopinavir, nelfinavir and saquinavir)
  • Blood-thinning drugs (e.g. warfarin)
  • Ciclosporin, an immunosuppressant drug
  • Oral contraceptive pills (oestrogen or progesterone).

This information does not contain all possible interactions. Therefore, before using primidone, tell your doctor or pharmacist of all the products you use.


An overdose of primidone may cause: lack of co-ordination and balance, loss of consciousness, breathing difficulties, coma (unable to wake) and excretion of crystals in the urine (crystalluria).

If you think you, or someone you care for, might have accidentally taken more than the recommended dose of primidone or intentional overdose is suspected, contact your local hospital, GP or if in England call 111. In Scotland call NHS 24. In Wales, call NHS Direct Wales. In the case of medical emergencies, always dial 999.


If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse events, nor should it be construed to indicate that use of a particular medicine is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any medicine, changing any diet, or discontinuing any course of treatment.

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