Mysoline (Primidone) - Oral

What Is Mysoline?

Mysoline (primidone) is a unique drug that can help eradicate or minimize the occurrence of seizures.

Our brain has cells called neurons. Neurons send messages throughout the body to do various actions. Seizures occur with an over-excitement of neurons. The neurons are so excited that they send more messages than normal throughout the body at one time. From there, the body becomes overstimulated, thus causing seizures or tremors.

Mysoline works by preventing neurons from firing as many messages by activating certain proteins in the body, known as GABA receptors. Once activated, they block the neurons from sending too many messages at once, which eliminates or minimizes seizure symptoms.

Mysoline, whose generic form is known as primidone, is categorized as an anticonvulsant medication. Since it is not available over-the-counter (OTC), your healthcare provider will need to prescribe Mysoline as a tablet to be taken by mouth to treat seizures.

Mysoline is available in an oral tablet form.

Drug Facts

Generic Name: Primidone 

Brand Name: Mysoline

Drug Availability: Prescription

Therapeutic Classification: Anticonvulsant

Available Generically: Yes

Controlled Substance: No

Administration Route: Oral

Active Ingredient: Primidone

Dosage Form(s): Tablet

What Is Mysoline Used For?

Mysoline is prescribed for seizure prevention and is also used off-label to treat benign essential tremors (involuntary and rhythmic shaking).

How to Take Mysoline

Mysoline comes as a tablet to take by mouth. It is usually taken three to four times a day with or without food. Take Mysoline around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your pharmacist to explain any part you do not understand. Take Mysoline exactly as directed. Do not take more or less of it or take it more often than prescribed by your healthcare provider.

Medication adherence is essential to a long-term improvement in signs and symptoms. Therefore, it is important to continue taking your medication even if you feel better.

If you accidentally miss a dose of your medication, take the missed dose as soon as you think about it. If it is too close to the time of your next dose, skip the missed dose and go back to your normal dose timing. Be careful not to take two doses at the same time or extra doses.


Mysoline must be stored in a safe place away from children and pets. Mysoline should be stored at room temperature in a clean, dry place.

Discard all unneeded medications. Do not flush your medication down the toilet, throw capsules away, or dispose of medication in the drain. Instead, dispose of your unnecessary medication through a medicine take-back program. 

Contact your pharmacist or your local waste control department to talk about medicine take-back programs in your community.

Off-Label Uses

Mysoline has an off-label use for the treatment of benign essential tremors.

How Long Does Mysoline Take to Work?

You should begin to see Mysoline work after the first hour of consumption.

What Are the Side Effects of Mysoline?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at or 800-FDA-1088.

Common Side Effects

Mysoline has been associated with varying side effects. Side effects tend to disappear with continued medication use or reduced doses. 

Common side effects of Mysoline include:

Serious Side Effects

More serious adverse events may occur with Mysoline use that may require immediate medical care. 

Seek emergency care and alert your healthcare provider right away in the event you experience any of the following:

  • Signs of an allergic reaction: If you have a severe allergic reaction to Mysoline, symptoms may include itchiness, rash, and breathing difficulties.
  • Digestive system-related effects: Digestive system-related effects (e.g., stomach pain, heartburn) are common. These effects, however, might become severe and excessive.
  • Inability to get or keep an erection (erectile dysfunction)
  • Blurred or compromised vision
  • Change in balance
  • New or worsening signs of depression

Call 911 if your symptoms feel life-threatening.

Report Side Effects

Mysoline may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Mysoline Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (chewable tablets, suspension, or tablets):
    • For seizures:
      • Adults, teenagers, and children 8 years of age or older—At first, 100 or 125 milligrams (mg) once a day at bedtime. Your doctor may increase your dose if needed. However, the dose is usually not more than 2000 mg a day.
      • Children up to 8 years of age—At first, 50 mg once a day at bedtime. Your doctor may increase your dose if needed.


The following modifications (changes) should be kept in mind when using Mysoline:

Severe allergic reaction: Avoid using Mysoline if you have a known allergy to it or any of its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Pregnancy: ​​The effects of Mysoline in human pregnancy and nursing infants are unknown. However, recent reports suggest an association between the use of anticonvulsant drugs by individuals with epilepsy and an elevated incidence of birth defects in children born to these birthing people. Consult with your healthcare provider if you are, or plan on becoming pregnant while using Mysoline.

When taking this medication, it is best to use additional forms of birth control, such as a condom or birth control pills, as other hormone-based birth control may not work as well to prevent pregnancy while taking Mysoline.

Breastfeeding: Caution is recommended with breastfeeding as limited data available on its effects is limited. Talk with your healthcare provider if you plan to breastfeed, weigh the benefits and risks of taking Mysoline while nursing, and the different ways available to feed your baby.

Adults over 65: Mysoline can also be used in older individuals. However, dose adjustments may be necessary. Consult your healthcare provider or pharmacist. If you are already taking other anti-seizure medications, your dose of Mysoline will need to be increased gradually.

Children: Dose adjustments are standard in prescribing Mysoline to children 8 years or younger, typically 125 to 250 milligrams (mg) three times daily.

People who smoke: Smoking can lower Mysoline's effectiveness. Try to stop smoking before starting Mysoline, and avoid smoking while taking Mysoline. Your healthcare provider can help you with this goal.

Missed Dose

If you miss a dose of Mysoline, you should take it as soon as you remember. If by the time you remember, you are close to the next scheduled dose, you should just take that dose and not the dose you missed.

Try to find ways that work for you to help yourself remember to keep your appointments and take your medication routinely. It is important to not take more than one dose at a time. If you miss a dose of Mysoline, you may be more likely to experience a seizure.

Overdose: What Happens If I Take Too Much Mysoline?

There is limited information available about Mysoline overdose. However, signs of potential Mysoline overdose include but are not limited to:

If you think that you're experiencing an overdose or life-threatening symptoms, seek immediate medical attention.

What Happens If I Overdose on Mysoline

If you think you or someone else may have overdosed on Mysoline, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Mysoline, call 911 immediately.


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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.

What Are Reasons I Shouldn't Take Mysoline?

Before taking Mysoline, talk with your healthcare provider if any of the following applies to you:

Mysoline is discouraged for users who are allergic to barbituric acid derivatives (organic chemical compounds) such as Donnatal (phenobarbital) and have a medical condition known as porphyria. Be sure to inform your healthcare provider if you’ve experienced any of the above conditions before or while taking Mysoline.

Use caution when taking Mysoline if you have kidney or liver issues. Your healthcare provider may advise against the use of Mysoline. Your healthcare provider may also adjust the dose of Mysoline to suit your specific needs. Before taking Mysoline, disclose any kidney or liver problems to your healthcare provider.

What Other Medications Interact With Mysoline?

There are some medications that may interact with Mysoline by reducing how well other drugs work, such as oral contraceptives, antibiotics like doxycycline, or tricyclic antidepressants. Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter (OTC) medicines and vitamins or supplements. 

Mysoline interacts with some drugs when taken together. It may change how certain medications work and can increase the risk for serious side effects. Drugs or drug groups that may interact negatively with Mysoline include:

If avoiding these types or individual medications isn't possible, your healthcare provider will adjust your dosages and closely monitor your side effects. Talk with your pharmacist or healthcare provider for more detailed information about medication interactions with Mysoline.

And be sure to talk with your healthcare provider about any other medicines you take or plan to take, including OTC, nonprescription products, vitamins, herbs, or plant-based medicines.

What Medications Are Similar?

Mysoline has been approved by the FDA for the treatment of seizures and other benign tremors. Other medications that can treat seizures include:

However, do not combine these medications with the use of Mysoline. You should always ask your pharmacist or your healthcare provider if you have questions or need further clarification.

Frequently Asked Questions

  • Should I take this medication with or without food?

    You do not need to take Mysoline with food. However, if you find yourself getting an upset stomach when taking this medication on an empty stomach, you may consider taking it with food. Ask your pharmacist or healthcare provider if you have any questions.

  • How can I remember to take my medicine?

    Taking your medicine at the same time every day is the best way to remember to take your medication. You can use a pillbox or set alarms on your phone. In addition, developing a routine that associates with taking the medication, like eating your breakfast before you take the medication, may help you hardwire your practice.  

  • What shouldn't I do while taking Mysoline?

    Avoid taking negatively interacting drugs, and smoking or drinking while completing your prescription. It's also important to discuss with your healthcare provider your current state of health, the potential for pregnancy, and any outstanding allergies before starting Mysoline.

How Can I Stay Healthy While Taking Mysoline?

To stay healthy while taking Mysoline, use your medication exactly as directed by your healthcare provider.

It’s also vital to maintain a healthy lifestyle, including moderate exercise, a healthy diet, and minimizing stress. Be sure to stay hydrated with water and get plenty of rest.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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