Phenobarbital 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 Phenobarbital suddenly, as your child may have more seizures.
Name of medicine
(This drug used to be known as phenobarbitone.)
Why is it important for my child to take Phenobarbital?
It is important that your child takes phenobarbital regularly so that they have fewer seizures.
What is Phenobarbital available as?
- Tablets: 15 mg, 30 mg, 60 mg; these tablets contain lactose
- Liquid medicine (orange): 15 mg in 5 mL; this contains a high concentration of alcohol and is not suitable for children with epilepsy
Other liquid medicines that do not contain alcohol can be prepared specially by your pharmacist. Check that you are always given the same strength of medicine.
When should I give Phenobarbital
Phenobarbital may be given once or twice a day.
- Once a day: This is usually in the evening.
- Twice a day: This should be once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example sometime between 7am and 8am and between 7pm and 8pm.
How much should I give?
Your doctor will work out the amount of Phenobarbital (the dose) that is right for your child. The dose will be shown on the medicine label.
Your doctor may suggest that your child starts with a low dose. They may then increase the dose as your child gets used to the medicine and depending on how they respond to it. Your doctor will explain what to do. If you are not sure how much to give, check with your doctor, nurse or pharmacist.
It is important that you follow your doctor’s instructions about how much to give.
How should I give Phenobarbital?
- Tablets should be swallowed with a glass of water, squash or juice. Your child should not chew the tablets.
- You can crush the tablet and mix it with a small amount of soft food such as yogurt, honey, or mashed potato. Make sure your child swallows it straight away, without chewing.
- 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 Phenobarbital 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 in the way that you have been told to by your doctor or epilepsy nurse. Phenobarbital may not stop your child’s seizures completely. If you are worried about whether it is helping, contact your doctor but continue to give the medicine.
What if my child is sick (vomits)?
- If your child is sick less than 30 minutes after having a dose of Phenobarbital, give them the same dose again.
- If your child is sick more than 30 minutes after having a dose of Phenobarbital, 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 Phenobarbital.
What if I give too much?
If you think you may have given your child too much Phenobarbital, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or 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).
Phenobarbital usually causes only mild side-effects, which should get better as your child’s body gets used to the medicine. If they are still a problem after 2 weeks or you are worried, contact your doctor, but continue to give phenobarbital.
- Your child’s behaviour may change – they may be drowsy (sleepy), seem less alert than normal and may say they cannot think clearly or remember things. They may develop a tremor (shakiness), or their coordination may be affected (they may seem clumsy). They may also have changes in mood and may be aggressive or hyperactive (more active than usual and finding it hard to relax). They may have sleep disturbances, such as difficulty getting to sleep.
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 www.mhra.gov.uk/yellowcard
Can other medicines be given at the same time as Phenobarbital?
- Some cough medicines and medicines for hay fever could make children drowsy (sleepy) if they are also taking phenobarbital. Check with a doctor or pharmacist before giving any of these medicines to your child.
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.
Phenobarbital and pregnancy
- Phenobarbital may harm an unborn baby.
- The oral contraceptive pill can be used safely in women or girls who are taking phenobarbital but its effectiveness may be reduced.
Is there anything else I need to know about this medicine?
- Some other medicines used to treat epilepsy may affect how well phenobarbital 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.
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.
- You may need to keep liquid medicine in the fridge – check the instructions on the bottle. Make sure the medicine does not freeze.
- 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 Phenobarbital and about other medicines used to treat epilepsy.
England: NHS 111
Scotland: NHS 24
Northern Ireland: NI Direct
Wales: NHS 111 Wales
0808 800 5050www.epilepsy.org.uk
01494 601 400epilepsysociety.org.uk
Version . © NPPG, RCPCH and WellChild, all rights reserved. Review by October 2015.
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.