Zonisamide for preventing seizures

This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.

Do not stop giving Zonisamide suddenly, as your child may have more seizures.

Name of medicine


Brand name: Zonegran

Why is it important for my child to take Zonisamide?

It is important that your child takes zonisamide regularly so that they have fewer seizures.

What is Zonisamide available as?

  • Capsules: 25 mg, 50 mg, 100 mg. All capsules contain gelatin. Zonegran capsules also contain soya.
  • Liquid medicine: Hospital pharmacies may be able to provide liquid medicine that contains either 10 mg or 8 mg in 1 mL of medicine. You will need to check which strength your child is given.

When should I give Zonisamide

You will usually start by giving Zonisamide once a day, while your child gets used to the medicine. This is usually in the evening.

When your child is used to Zonisamide, it may sometimes be given twice a day: once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example sometime between 7 am and 8 am and between 7 pm and 8 pm

How much should I give?

Your doctor will work out the amount of Zonisamide (the dose) that is right for your child. The dose will be shown on the medicine label.

When you first start giving Zonisamide to your child, you will probably give them a low dose, which may be increased bit by bit over a few days or weeks. This helps your child to get used to the medicine. Your doctor will explain what to do.

It is important that you follow your doctor’s instructions about how much to give.

How should I give Zonisamide?


  • Capsules should be swallowed whole with a glass of water. Your child should not chew the capsule. You can open the capsule and mix the contents into a teaspoonful of soft food (e.g. honey or jam). Make sure your child swallows it straight away, without chewing.

Liquid medicine

  • Shake the medicine well.
  • Measure out the right amount using an oral syringe or a medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.

When should the medicine start working?

It may take a few weeks for Zonisamide to work properly, so your child may still have their symptoms for a while. Continue to give the medicine as you have been told to by your doctor.

What if my child is sick (vomits)?

  • If your child is sick less than 30 minutes after having a dose of Zonisamide, give them the same dose again.
  • If your child is sick more than 30 minutes after having a dose of Zonisamide, do not give them another dose. Wait until the next normal dose.

If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.

What if I forget to give it?

If you usually give it once a day in the evening: If you remember before bedtime, give the missed dose. You do not need to wake a sleeping child to give a missed dose. You can give the missed dose in the morning, as long as this is at least 12 hours before the evening dose is due.

If you usually give it twice a day: If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7am, you can give the missed dose at any time up to 11am. If you remember after that time, do not give the missed dose. Give the next dose as usual.

Never give a double dose of Zonisamide.

What if I give too much?

If you think you may have given your child too much Zonisamide, contact your doctor or local NHS services (details at end of leaflet) or take your child to hospital. Have the medicine container or packaging with you, even if it is empty. This will be useful to the doctor.

It can be dangerous to give too much Zonisamide.

Are there any possible side effects?

We use medicines to make our children better, but sometimes they have other effects that we don’t want (side effects).

Side effects you must do something about

If your child is short of breath or is wheezing, or their face, lips or tongue start to swell, or they develop a rash, they may be allergic to Zonisamide. Take your child to hospital or phone for an ambulance straight away.

If your child has a rash, is generally unwell and has a fever (temperature above 38°c) or unusual bruises or bleeding, take them to your doctor or hospital straight away, as this may indicate a more serious reaction.

Your child may sweat less whilst taking Zonisamide. Be careful that they don’t overheat, particularly in hot weather and during exercise; make sure that they drink plenty of water.

Other side-effects you need to know about

  • Your child may get stomach pains or feel sick (nausea), dizzy or drowsy (sleepy). Your child may be unsteady.
  • Their behaviour may also change, and they may become moody or seem nervous and find it difficult to concentrate. Their sleep may be disturbed.

These effects should get better as your child’s body gets used to the medicine. If they don’t, contact your doctor for advice.

  • Kidney stones are more common when taking Zonisamide. You can help to prevent this by making sure that your child drinks plenty of fluids. If your child gets severe pain in their back or groin, has pain when passing urine (doing a wee), or there is blood in the urine, take them to your doctor straight away.

There may sometimes be other side effects that are not listed above. If you notice anything unusual and are concerned, contact your doctor. You can report any suspected side effects to a UK safety scheme at

Can other medicines be given at the same time as Zonisamide?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.

Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal and complementary medicines.

Zonisamide should not be taken with some medicines that you get on prescription. It is important to tell your doctor and pharmacist about any other medicines your child is taking before starting Zonisamide.

Epilepsy and pregnancy

  • Pregnancy presents a risk to both the mother with epilepsy and her unborn baby. If your daughter has sex, it is essential that she uses contraception to prevent pregnancy.
  • If your daughter is worried that she may be pregnant, it is important that she sees her doctor as early as possible. Your daughter should keep taking her medicine until she sees her doctor.

Zonisamide and pregnancy

  • Doctors do not know yet whether zonisamide can harm an unborn baby.
  • The oral contraceptive pill can be used safely by women or girls who are taking zonisamide.

General advice about medicines

Advice about medicines for seizures

  • If your doctor decides to stop a particular medicine, they will discuss this with you. They will usually reduce the dose bit by bit.
  • It is best that your child always has the same brand of each medicine, as there may be differences between brands. Keep a record of which medicines your child has.
  • Try to give medicines at about the same times each day, to help you remember.
  • Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
  • Make sure that you always have enough medicine. Order a new prescription at least 2 weeks before you will run out.
  • Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.

Do not suddenly stop giving any medicines for seizures to your child. If you are worried, contact your doctor but carry on giving the medicine to your child as usual.

If your child seems to have more seizures than usual, contact your doctor or epilepsy nurse.

Do not change the dose of any medicine without talking to your doctor first.

If you think someone else may have taken the medicine by accident, contact your doctor straight away.

Where should I keep this medicine?

  • Keep the medicine in a cupboard, away from heat and direct sunlight.
  • Liquid medicine may need to be kept in the fridge – this will be shown on the label.
  • Make sure that children cannot see or reach the medicine.
  • Keep the medicine in the container it came in.

Who to contact for more information?

Your child’s doctor, pharmacist or nurse will be able to give you more information about Zonisamide and about other medicines used to treat epilepsy.

England: NHS 111

Tel 111

Scotland: NHS 24

Northern Ireland: NI Direct

Wales: NHS 111 Wales

Epilepsy Action

0808 800 5050

Epilepsy Society

Young Epilepsy

Copyright disclaimer

Version [3]. © NPPG, RCPCH and WellChild, all rights reserved. Review by March 2022.

The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website,

We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.