Phenytoin for preventing seizures

This leaflet is about the use of phenytoin to prevent epileptic seizures. (Seizures may also be called convulsions or fits).

This leaflet has been written specifically about the use of this medicine in children. The information may differ from that provided by the manufacturer. Please read this leaflet carefully. Keep it somewhere safe so that you can read it again.

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

Name of drug

Phenytoin
Brand name: Epanutin®

Why is it important for my child to take this medicine?

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

What is phenytoin available as?

  • Tablets: 100mg (white)
  • Capsules: 25 mg (white and purple), 50 mg (white and pink), 100 mg (white and orange), 300 mg (white and green)
  • Infatabs®: 50 mg (yellow)
  • Liquid medicine: 30 mg in 5 mL (red) and 90 mg in 5mL (usually pink)

When should I give phenytoin?

Phenytoin is usually 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 and 8 am and between 7 and 8 pm.

Your doctor may tell you to start by giving phenytoin once a day until your child gets used to it. This is usually in the evening.

How much should I give?

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

When you first start giving phenytoin to your child, you will give them a small amount and then increase the dose bit by bit over a few days or weeks. This helps your child to getused 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 it?

Phenytoin for preventing seizuresTablets should be swallowed whole with a glass of water, milk or juice. Your child should not chew the tablet.


Phenytoin for preventing seizuresCapsules should be swallowed whole with a glass of water, milk or juice. Your child should not chew the capsules.


Phenytoin for preventing seizures

Infatabs® can be chewed or swallowed whole.



Phenytoin for preventing seizuresLiquid medicine Measure out the right amount using an oral syringe or 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 will take a few weeks for phenytoin to work properly, so your child may still have seizures during this time. This is because the amount of medicine has to be increased slowly. 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 taking a dose of phenytoin, give the same dose again.
  • If your child is sick more than 30 minutes after taking a dose of phenytoin, you do not need to give them another dose. Wait until the next normal dose.

What if I forget ?

If you remember within 4 hours, give your child the missed dose. For example, if you usually give a dose at 7 am, you can give the missed dose at any time up to 11 am. If you remember after this time, do not give the missed dose. Wait until it is time to give the next normal dose.

Never give a double dose of phenytoin.

What if I give too much?

If you think you may have given your child too much phenytoin, contact your doctor or NHS Direct (0845 4647 in England and Wales; 0845 24 24 24 in Scotland) or take your child to hospital.

Take the medicine packaging with you, even if it is empty. This will be useful to the doctor. Have the packaging with you if you telephone for advice.

Are there any possible side-effects?

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

Phenytoin usually causes only mild side-effects, which should get better as your child’s body gets used to the medicine.

Side-effects that you must do something about

If your child develops a blotchy red skin rash, contact your doctor straight away, as your child may be allergic to phenytoin. The rash usually affects the whole
body but may just affect the face. You may also see blisters in the mouth, and your child may have a high temperature (fever).

Other side-effects you need to know about

  • Your child may have difficulty with coordination or balance. They may feel sick (nausea) and their vision may be blurred or double. They may also be drowsy (sleepy). These effects should get better after about a week. If they don’t, contact your doctor.
  • A few children get a mild tremor (shakiness) of their fingers. This may happen after 2–3 weeks and usually goes away. If it doesn’t, contact your doctor.
  • The skin on your child’s face may look and feel coarse and become slightly hairy if they have been taking phenytoin for longer than 3–4 months. The skin will slowly return to normal after phenytoin is stopped.
  • Your child may also get spots that look like acne. Keeping the face clean will help to reduce this.
  • Your child’s gums may start to get thicker if they have been taking phenytoin for longer than 4–6 months. Brushing the teeth for at least 2 minutes twice a day will help to reduce this effect, and the gums will return to normal after phenytoin is stopped. A dentist should check your child’s teeth every 6 months.

Can other medicines be given at the same time?

  • 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 or complementary medicines.

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 adequate contraception to prevent an unplanned pregnancy.
  • If your daughter thinks that she may be pregnant, it is important that she sees your family doctor as early as possible. Your daughter should keep taking her medication until she sees her doctor.

Phenytoin and pregnancy

  • Phenytoin may harm an unborn baby.
  • The oral contraceptive pill can be used safely in women or girls who are taking phenytoin.

Is there anything else I need to know about this medicine?

  • Some other medicines used to treat epilepsy may affect how well phenytoin works, or may cause side-effects. If you are worried about side-effects, or if your child seems to be having more fits, contact your doctor or epilepsy nurse.
  • It is best that your child always has the same brand, and strength, of this medicine, because there are differences between brands. Keep a record of which brand, and strength, your child has.
  • Your doctor may want to measure the amount of phenytoin in your child’s blood.

General advice about medicines for epilepsy

Do not suddenly stop giving any of these medicines to your child, as they may have a seizure. If you are worried, talk to 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 your epilepsy nurse.

  • If your doctor decides to stop a particular medicine, they will discuss this with you. You will usually reduce the dose bit by bit.

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

  • 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 every day, to help you remember.
  • Only give the medicine(s) to your child. Never give them to anyone else, even if their conditoin appears to be not change the dose of any drug without talking to your doctor first.

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

  • 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.

Where I should keep this medicine?

  • Keep the medicine in a cupboard, away from heat and direct sunlight. It does not need to be kept in the fridge.
  • Make sure that children cannot see or reach it.
  • Keep the medicine in the container it came in.

Who to contact for more information

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


You can also get useful information from:


Publication Date

8/12/2011

Copyright Disclaimer

Version 1.2, February 2008 (November 2011). © NPPG, RCPCH and WellChild 2011, all rights reserved.

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, www.medicinesforchildren.org.uk

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