How does this medication work? What will it do for me?

This medication is used to manage and prevent certain types of seizures (those caused by absence [petit mal] epilepsy). It may be used at the same time as other medications that are used to control different types of seizures. It helps to control seizures by working on the central nervous system.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?


Each soluble gelatin capsule, embossed "PD 237" contains ethosuximide 250 mg. Nonmedicinal ingredients: D&C Yellow No. 10, FD&C Red No. 3, gelatin, glycerin, polyethylene glycol, and sorbitol.


Each 5 mL contains ethosuximide 250 mg. Nonmedicinal ingredients: alcohol, citric acid anhydrous, FD&C Yellow No. 6, flavouring agents, glycerin, purified water, saccharin sodium, sodium benzoate, sodium citrate, sucrose, and vanillin. Gluten-, lactose-, parabens-, sulfite-, and tartrazine-free.

How should I use this medication?

Adults: The dose of ethosuximide varies according to the needs and age of the person using the medication and their response to treatment. Often a dose of 1 g to 1.5 g daily in divided doses controls seizures in adults.

Children: The dose for children 3 to 6 years of age is 250 mg daily. For older children, it is 500 mg daily taken in divided doses.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Ethosuximide should not be taken by anyone who:

  • is allergic to ethosuximide or to any of the ingredients of the medication
  • is allergic to any of the medications in the succinimide family (e.g., methsuximide)

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • clumsiness or unsteadiness
  • dizziness
  • drowsiness
  • headache
  • hiccups
  • irritability
  • loss of appetite
  • nausea or vomiting
  • stomach cramps

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • aggressiveness
  • chills
  • depression
  • difficulty concentrating
  • increased chance of certain types of seizures
  • mood or mental changes
  • muscle pain
  • nightmares
  • nosebleeds or other unusual bleeding or bruising
  • shortness of breath
  • skin rash and itching
  • sore throat and fever
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual tiredness or weakness
  • wheezing, tightness in the chest, or difficulty breathing

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood disorders: Blood disorders, although infrequent, may be serious and have been reported to be associated with the use of ethosuximide. You will probably have periodic blood tests when taking this medication.

Drowsiness/reduced alertness: Ethosuximide may impair the mental or physical abilities required for potentially dangerous activities such as driving or operating machinery. People taking this medication should determine how it affects them before undertaking such activities.

Kidney or liver function: People with impaired kidney or liver function should discuss with their doctor the risks and benefits of taking this medication.

Lupus: Cases of systemic lupus erythematosus (SLE) have been reported with the use of ethosuximide.

Pregnancy: Women subject to major seizures should not stop taking this medication during pregnancy. For women subject to minor seizures, the risk of stopping the medication prior to or during pregnancy should be weighed against the risk of birth defects. If you become pregnant while taking this medication, contact your doctor right away.

Breast-feeding: Women who take ethosuximide should not breast-feed their infants.

Children: The safety and effectiveness of this medication have not been established for children under 3 years of age.

What other drugs could interact with this medication?

There may be an interaction between ethosuximide and any of the following:

  • lamotrigine
  • phenytoin
  • primidone
  • valproic acid

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.