Ethosuximide is used to control absence seizures. This is in a class of medications called anticonvulsants. Ethosuximide stabilizes electrical activity in the brain. Controlling absence seizures can help an individual reach their full potential whether in school or at home. Once they’ve taken a seizure medicine, the treatment usually continues for at least 2 years. 

The Food and Drug Administration (FDA) already approved this prescription. Ethosuximide comes as a capsule with a dosage strength of 250 mg for oral use. 

Absence seizures

This condition involves brief and sudden lapses of consciousness. They are more common in children than in adults. An absence seizure causes a loss of consciousness for 30 seconds or less. The person simply stops speaking or moving. They stare straight ahead blankly and do not respond to questions. When the absence of seizure ends, the person goes back to their normal activity without knowing what happened. Signs and symptoms of this condition may include:

  • Lip-smacking
  • A sudden stop in motion without falling
  • Eyelid flutters
  • Finger rubbing
  • Chewing motions
  • Small movements of both hands 

Many children appear to have a genetic predisposition to absence seizures. In general, seizures are caused by abnormal electrical impulses from nerve cells in the brain. The nerve cells of the brain normally send electrical and chemical signals across the synapses that connect them. In people with seizures, the brain’s usual electrical activity is altered. During an absence seizure, these electrical signals repeat themselves over and over in a 3-second pattern. Certain factors are common to children who have absence seizures including;

  • Gender – absence seizures are more common in girls
  • Age – absence seizures are more common in children between the ages of 4 to 14
  • Family members who have seizures – nearly half of children with absence seizures have a close relative who has seizures 

While most children outgrow absence seizures, some:

  • Eventually have full convulsions such as generalized tonic-clonic seizures
  • Must take anti-seizure medications throughout life to prevent seizures

Other complications can include:

  • Social isolation
  • Learning difficulties
  • Behavior problems

How It Works

Ethosuximide works by preventing the repetitive firing of electrical signals. This raises the threshold of the brain to stimuli that cause seizures and helps prevent seizures. 

This drug stabilizes the electrical activity in the brain. The brain and nerves are made up of many nerve cells that communicate with each other through electrical signals. These signals must be carefully regulated for the brain and nerves to function properly. When abnormally rapid and repetitive electrical signals are released in the brain, it becomes over-stimulated. The normal function is also disturbed. This results in fits or seizures. 

How To Use

Follow the directions of your doctor. Call if you have any questions. Ask the doctor what to do if you forget a dose. The way medicine is taken depends on what form the doctor has prescribed. Capsules should be swallowed as a whole. Don’t chew them or break them open. You may take Ethosuximide either with food or without food. But, many people find that stomach upset is less of a problem if they take it with meals.

It is important to exactly follow the dosing instruction of your doctor. Your doctor will start you on a low dose and gradually increase it. It may take several weeks or months to reach the best dose for you and to get the full benefit from this medication. Remember to take the dose of this drug at the same time each day. 

Be sure to take only the amount that the doctor prescribes. If you think you’ve taken a little too much, call your doctor for advice. For a larger overdose, call your local poison control center or emergency room right away unless you have special instructions from the doctor. Don’t stop taking Ethosuximide or change the amount you take without talking to the doctor first. Serious problems sometimes occur when people stop taking Ethosuximide suddenly. 

Side Effects

Common side effects:

  • Dizziness
  • Drowsiness
  • Headache
  • Tiredness
  • Stomach cramps
  • Stomach upset
  • Loss of appetite
  • Vomiting
  • Nausea
  • Weight loss 
  • Diarrhea
  • Swelling in your tongue or gums
  • Loss of balance or coordination
  • Unusual vaginal bleeding 

Call your doctor at once if you have:

  • Chills 
  • Fever 
  • Flu symptoms 
  • Feeling very weak
  • Hallucinations, confusion, unusual thoughts or behavior
  • Worsening seizures
  • lupus-like syndrome (swollen glands, joint pain or swelling with fever, muscle aches, vomiting, chest pain, and patchy skin color)
  • Signs of inflammation in your body (flu symptoms, swollen glands, easy bruising or bleeding, severe tingling or numbness, muscle weakness, upper stomach pain, jaundice, chest pain, trouble breathing, new or worsening cough)
  • Severe skin reaction (sore throat, fever, burning in your eyes, swelling in your face or tongue, skin pain, blistering and peeling)


  • This medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won’t affect your performance.
  • This medicine may rarely cause a decrease in the normal amounts of blood cells in the blood. Your doctor may want to take a blood test to check your blood cells. 
  • Your kidney and liver function should be monitored while you are taking this medicine.
  • This drug should be used with caution in people with decreased kidney or liver function. 
  • If you are pregnant or planning to become pregnant, talk to your doctor first before taking this medicine. 
  • This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor right away.
  • This medicine passes into breast milk. The manufacturer recommends that mothers taking this medicine should avoid breastfeeding. Seek medical advice from your doctor.
  • This is not recommended for use in people with hereditary blood disorders and a rare hereditary problem of fructose intolerance. 
  • Inform your doctor about the other medications you may be taking including vitamins or herbal supplements. 
  • Store them at room temperature, protected from heat and out of the reach of children.