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Ethosuximide for epilepsy

Emeside, Epesri

Take ethosuximide regularly. Most people are prescribed two doses a day.

Do not stop taking it unless your doctor tells you to.

Ethosuximide may make you feel sick (nausea) when you first start taking it. This should soon settle down.

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About ethosuximide

Type of medicine

An antiepileptic medicine

Used for

Epilepsy with absence seizures

Also called

Emeside®, Epesri®

Available as

Capsules and oral liquid medicine

Absence seizures are a form of epilepsy. They mainly occur in children and young people. Absence seizures are a brief loss of consciousness (an 'absence') for a few seconds, and can appear like daydreaming. Although no underlying cause for this type of seizure can be found, it is thought that the brain develops a low threshold for bursts of abnormal electrical activity. Ethosuximide is one of the medicines commonly prescribed for this type of epilepsy. It helps to reduce absence seizures by stabilising the abnormal electrical activity in the brain.

Ethosuximide is occasionally prescribed for some other types of seizures.

Before taking ethosuximide

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you (or your child if you are the carer) start taking ethosuximide it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have any problems with the way your kidneys work, or with the way your liver works.

  • If you have a rare inherited blood disorder called porphyria.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to take ethosuximide

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about ethosuximide and will provide you with a full list of the side-effects which you may experience from taking it.

  • Take ethosuximide exactly as your doctor tells you to. Your dose will be printed on the label of the pack of medicine to remind you about what the doctor said. It is usual to start treatment on a low dose, and then for the dose to be increased gradually to a regular maintenance dose. It is usual to take two doses each day. Doses for children are tailored to their age and weight.

  • Try to take your doses at the same times of day, each day. Having a routine will help you to remember to take your doses regularly. You can take ethosuximide either before or after meals. If you are taking capsules, swallow them with a drink of water.

  • If you (or your child) have been given ethosuximide oral liquid medicine, remember to shake the bottle well before you measure out the dose. It is also a good idea to brush your (or your child's) teeth after each dose as the medicine contains sugar.

  • If you forget to take a dose, take it as soon as you remember, unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a forgotten dose.

Getting the most from your treatment

  • When you first start a new treatment for epilepsy there may be a change in the number or type of seizures you experience. Your doctor will advise you about this.

  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress.

  • Different formulations and makes of ethosuximide can act in a slightly different way in your body. Because of this, your doctor may recommend that you continue to take ethosuximide from the same manufacturer each time you obtain a new supply. If so, each time you collect a prescription, check to make sure your supply looks the same and that the name is the same. If you are unsure, or if you have any questions about your prescription, please ask your pharmacist to advise you.

  • If you buy any medicines, check with a pharmacist that they are suitable for you to take.

  • While you are being treated for epilepsy there is a small risk that you may develop mood changes, distressing thoughts and feelings about suicide. If this happens, you must tell your doctor about it straightaway.

  • People with epilepsy must stop driving at first. Your doctor will advise you about when it may be possible for you to start driving again. This will usually be after a year free of seizures.

  • Antiepileptic medicines can harm an unborn child. If you are a woman, make sure you have discussed with your doctor which types of contraception are suitable for you and your partner. If you want to have a family, discuss this with your doctor so that you can be given advice from a specialist before you become pregnant.

  • You need to take ethosuximide regularly every day. Do not stop taking it unless your doctor tells you to stop. Stopping treatment suddenly can cause problems and your doctor will want you to reduce your dose gradually if this becomes necessary.

  • If you drink alcohol, ask your doctor for advice. Your doctor may advise you not to drink alcohol while you are on this medicine.

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Can ethosuximide cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with ethosuximide. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common ethosuximide side-effects (these affect less than 1 in 10 people)

What can I do if I experience this?

Feeling sick (nausea) or being sick (vomiting), tummy (abdominal) discomfort

Try to stick to simple meals - avoid rich or spicy foods


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know

Feeling dizzy, tired or sleepy

If this happens, do not drive and do not use tools or machines


Drink plenty of water to replace the lost fluids

Lack of appetite, feeling unsteady, itchy skin rash, mood changes

If any of these become troublesome, speak with your doctor for advice

Important: your doctor will discuss with you the possibility that ethosuximide can cause blood disorders. Although these occur less commonly than the side-effects listed above, it is important that you contact your doctor straightaway if you experience any of the following symptoms:

  • A high temperature (fever).

  • Mouth ulcers.

  • Unexplained bruising or bleeding.

If you experience any other symptoms which you think may be due to ethosuximide, speak with your doctor or pharmacist for further advice.

How to store ethosuximide

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

MHRA - Reporting adverse reactions

Report suspected side effects to medicines, vaccines, e-cigarettes, medical device incidents, defective or falsified (fake) products to the Medicines and Healthcare products Regulatory Agency to ensure safe and effective use.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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