Uses
What is primidone used for?
Primidone is commonly used to control certain types of seizures.
Primidone may also be used for other conditions as determined by your healthcare provider.
How does primidone work (mechanism of action)?
Primidone works to control seizures by calming brain activity.
How is primidone supplied (dosage forms)?
Primidone is available as Mysoline and generic primidone in the following dosage forms that are taken by mouth.
- 50 mg oral tablets
- 125 mg oral tablets
- 250 mg oral tablets
How should I store primidone?
Primidone should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store away from direct sunlight in a tightly closed bottle, in a cool, dry place.
Side Effects
What are the most common side effects of primidone?
The most common side effects of primidone are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Trouble with balance or coordination
- Feeling dizzy or like you are spinning
There may be other side effects of primidone that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of primidone?
While less common, the most serious side effects of primidone are described below, along with what to do if they happen.
Severe Allergic Reactions. Primidone may cause allergic reactions, which can be serious. Stop taking primidone and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching, skin rash, or pale red bumps on the skin called hives
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Suicidal Thoughts and Actions. Primidone may cause suicidal thoughts or actions in a small number of people. If you are about to harm yourself, call 911 or call or text 988, the Suicide & Crisis Lifeline. Call your healthcare provider right away if you have any of the following symptoms.
- New or increased thoughts of suicide or death
- Suicide attempt
- New or increased feelings of anxiety, depression, or other unusual changes in mood or behavior
Sleepiness. Primidone can make you very sleepy, especially when you first start taking it. Do not drive or do other activities that require alertness or coordination until you know how primidone affects you.
Blood Disorders. Primidone can cause blood disorders, such as low levels of certain types of white blood cells, known as granulocytopenia and agranulocytosis, and low levels of red blood cells, which can cause anemia. Stop taking primidone and get help right away if you have any of the following symptoms of blood disorders.
- Fever
- Shortness of breath
- Pale or yellowish skin
- Easy bruising or bleeding
- Frequent infection
- Unusual weakness or tiredness
- Dizziness, lightheadedness, or feeling like you are about to pass out
- Headache
- Fast or abnormal heartbeat
Warnings & Precautions
Who should not use primidone?
Allergies to Ingredients. People who are allergic to any of the following should not take primidone.
- Primidone
- Mysoline
- Phenobarbital
- Any of the ingredients in the specific product dispensed
Your pharmacist can tell you all of the ingredients in the specific primidone products they stock.
Porphyria. Primidone should not be used if you have porphyria. Porphyria is a genetic disorder that most often affects your skin. Tell your healthcare provider if you have porphyria.
What should I know about primidone before using it?
Do not take primidone unless it has been prescribed to you by a healthcare provider. Take it as prescribed.
Do not share primidone with other people, even if they have the same condition as you. It may harm them.
Keep primidone out of the reach of children. Primidone is a controlled substance because it can be misused or lead to dependence. Store primidone in a safe place to protect it from theft. It is illegal to sell or give away this medicine.
Primidone can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how primidone affects you.
Do not stop taking primidone without talking to your healthcare provider. Stopping primidone suddenly can cause seizures that keep going, called status epilepticus. If you need to stop taking primidone, your healthcare provider will give you instructions on how to stop the medicine.
What should I tell my healthcare provider before using primidone?
Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are taking. This will help them determine if primidone is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.
- Mental health conditions, such as depression or mood problems
- Suicidal thoughts or actions
Other Medicines and Supplements. Primidone may interact with other medicines and supplements. Before taking primidone, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are taking. See the Interactions section for more details.
Pregnancy. Primidone may cause harm to an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take primidone while you are pregnant or trying to get pregnant. If you become pregnant while taking primidone, you can register for the North American Antiepileptic Drug Pregnancy Registry by calling 888-233-2334 or at www.aedpregnancyregistry.org. This registry collects safety information about the use of medicines to control seizures during pregnancy.
Breastfeeding. Primidone passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take primidone while breastfeeding.
Interactions
Does primidone interact with foods or drinks?
There are no known interactions between primidone and foods or drinks.
It is likely best to avoid drinking alcohol while taking primidone. It is unknown if drinking alcohol will affect primidone. The risk of dizziness or sleepiness may be increased if you drink alcohol while taking primidone.
Does primidone interact with other medicines (drug interactions)?
Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are taking.
In particular, make sure that you discuss if you are taking any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety before taking primidone.
This may not be a complete list of medicines that can interact with primidone. Always check with your healthcare provider.
Overdose/Missed Dose
What should I do if I accidentally use too much primidone?
If you or someone else has used too much primidone, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
What should I do if I miss a dose of primidone?
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.
Are you currently using Primidone (Mysoline)?
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