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Ethosuximide

Generic name: ethosuximide [ ETH-oh-SUX-i-mide ]
Brand name: Zarontin
Dosage forms: oral capsule (250 mg), oral syrup (250 mg/5 mL)
Drug class: Succinimide anticonvulsants

Medically reviewed by Drugs.com on Jul 17, 2023. Written by Cerner Multum.

What is ethosuximide?

Ethosuximide is an anti-epileptic medication, also called an anticonvulsant.

Ethosuximide is used alone or in combination with other medications to treat absence seizures (also called "petit mal" seizures) in adults and children.

Ethosuximide may also be used for purposes not listed in this medication guide.

Ethosuximide side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Ethosuximide may cause serious side effects. Call your doctor at once if you have:

Common side effects of ethosuximide may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Warnings

Do not stop using ethosuximide suddenly. Stopping suddenly may cause increased seizures.

Before taking this medicine

You should not use ethosuximide if you are allergic to ethosuximide or to other seizure medications.

To make sure ethosuximide is safe for you, tell your doctor if you have:

Some people have thoughts about suicide when taking an anticonvulsant. Your doctor should check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Follow your doctor's instructions about taking seizure medication if you are pregnant. Do not start or stop taking this medicine without your doctor's advice, and tell your doctor right away if you become pregnant. Ethosuximide may cause harm to an unborn baby, but having a seizure during pregnancy could harm both mother and baby. The benefit of preventing seizures may outweigh any risks to the baby.

If you are pregnant, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of ethosuximide on the baby.

Ethosuximide can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Ethosuximide should not be given to a child younger than 3 years old.

How should I take ethosuximide?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

While using ethosuximide, you may need frequent blood tests. Your kidney function may also need to be checked.

Do not stop using ethosuximide suddenly, even if you feel fine. Stopping suddenly may cause increased seizures. Follow your doctor's instructions about tapering your dose.

Call your doctor if your seizures get worse or you have them more often while taking ethosuximide.

Wear a medical alert tag or carry an ID card stating that you take ethosuximide. Any medical care provider who treats you should know that you take seizure medication.

Use ethosuximide regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

Store at room temperature away from moisture and heat. Do not allow liquid medicine to freeze.

Ethosuximide dosing information

Usual Adult Dose for Seizures:

Initial dose: 500 mg orally once a day
-Increase dose in small increments, for example 250 mg daily every 4 to 7 days, until optimal seizure control with minimal side effects is achieved
Maintenance dose: Individualized; generally, a dose that provides efficacy and tolerability with a plasma level within the accepted therapeutic range (40 to 100 mcg/mL)

Comments:
-Doses exceeding 1.5 g per day should be administered only under strict supervision of a physician.
-For higher daily doses, consider twice a day dosing.
-This drug may be administered in combination with other anticonvulsants when other forms of epilepsy coexist.

Use: For the control of absence (petit mal) seizures.

Usual Pediatric Dose for Seizures:

3 to 6 years old:
Initial dose: 250 mg orally once a day

6 years or older:
Initial dose: 500 mg orally once a day

Titration: Increase dose in small increments, for example 250 mg daily every 4 to 7 days, until optimal seizure control with minimal side effects is achieved
Maintenance dose: Individualized; generally, a dose that provides efficacy and tolerability with a plasma level within the accepted therapeutic range (40 to 100 mcg/mL)
Optimal dose for most pediatric patients: 20 mg/kg/day; some authorities have found doses up to 40 mg/kg/24 hours are needed to obtain therapeutic levels

Comments:
-Doses exceeding 1.5 g per day should be administered only under strict supervision of a physician.
-For higher daily doses, consider twice a day dosing.
-This drug may be administered in combination with other anticonvulsants when other forms of epilepsy coexist.

Use: For the control of absence (petit mal) seizures.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, extreme drowsiness, and weak or shallow breathing.

What should I avoid while taking ethosuximide?

Drinking alcohol with ethosuximide can cause side effects.

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

What other drugs will affect ethosuximide?

Taking this medicine with other drugs that make you dizzy or sleepy can worsen this effect. Ask your doctor before taking ethosuximide with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Tell your doctor about all your current seizure medications, and any you start or stop using.

Other drugs may interact with ethosuximide, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.