What is Ethosuximide: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Ethosuximide overview

BRAND NAMES:

  • Zarontin

Generic Names:

  • Ethosuximide

Uses:

  • Treats seizures in patients who have epilepsy.

Therapeutic Classes:

  • Anticonvulsant

Forms:

  • Liquid, Liquid Filled Capsule

How it’s taken:

  • By mouth

What is Ethosuximide used for?

Zarontin is used alone or in combination with other medications to treat absence seizures. Zarontin can be used by adults and children, older than 3 years. It should not be used in patients with a history of hypersensitivity to succinimides.

What form(s) does Ethosuximide come in

  • Liquid

  • Liquid Filled Capsule

What are common Ethosuximide doses?

  • Capsule 250MG

  • Bottle 473ML of 250MG/5ML

  • Bottle 474ML of 250MG/5ML

Common Ethosuximide prescriptions

  • Ethosuximide
    473ml of 250mg/5ml bottle

  • Ethosuximide
    474ml of 250mg/5ml bottle

  • Ethosuximide
    250mg capsule

How to take Ethosuximide

  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not freeze the oral liquid.

  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

  • This medicine can be used with other seizure medicines. Keep using all of your seizure medicines unless your doctor tells you to stop.

  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.

  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

  • This medicine can be used with other seizure medicines. Keep using all of your seizure medicines unless your doctor tells you to stop.

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not freeze the oral liquid.

What to do if you miss a dose of Ethosuximide

Ethosuximide contraindications

  • This medicine is not right for everyone. Do not use it if you had an allergic reaction to ethosuximide or similar medicines.

Ethosuximide warnings

  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

  • This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.

  • This medicine may cause the following problems:Low blood cell counts, which may cause bleeding problems or increase your risk for infectionLupusSerious skin reactionsDrug reaction with eosinophilia and systemic symptoms (DRESS), which may damage organs such as the liver, kidney, or heart

  • This medicine can increase depression or thoughts of suicide. Tell your doctor right away if you start to feel more depressed and have thoughts about hurting yourself.

  • Tell your doctor knows if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, lupus, or a history of depression.

  • Yellow skin or eyes

  • Unusual bleeding, bruising, or weakness

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Ethosuximide interactions

  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

  • This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

  • Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.

  • This medicine may cause the following problems:Low blood cell counts, which may cause bleeding problems or increase your risk for infectionLupusSerious skin reactionsDrug reaction with eosinophilia and systemic symptoms (DRESS), which may damage organs such as the liver, kidney, or heart

  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.

  • Some foods and medicines can affect how ethosuximide works. Tell your doctor knows if you using phenytoin or valproic acid.

Ethosuximide side effects

Serious Side Effects

  • Chest pain, trouble breathing

  • Feeling depressed, irritable, or restless

  • Blistering, peeling, or red skin rash

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

  • Thoughts of hurting yourself, other unusual thoughts or behaviors

  • Fever, skin rash, or swollen glands in your armpits, neck, or groin

  • Yellow skin or eyes

  • Fever, chills, cough, sore throat, and body aches

  • Unusual bleeding, bruising, or weakness

Less Serious Side Effects

  • Dizziness or drowsiness

  • Weight loss

  • Diarrhea, nausea, vomiting, loss of appetite, or stomach pain

  • Headache

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