Carbamazepine

Important

The brand Carbagen has been discontinued. If you are currently taking Carbagen, please contact your doctor for an alternative brand to be prescribed.

Updated: 28 September 2020

Carbamazepine is a medicine used to treat epilepsy.

It can also be taken for nerve pain caused by diabetes (peripheral neuropathy) or if you have a painful condition of the face called trigeminal neuralgia.

Carbamazepine is occasionally used to treat bipolar disorder when other medicines have not worked.

This medicine is only available on prescription. It comes as tablets, a liquid that you drink and suppositories (medicine that you push gently into your anus).

• It's usual to take carbamazepine between 1 and 4 times a day. You can take it with or without food.
• Common side effects of carbamazepine include feeling sleepy, dizziness, headaches and feeling or being sick. These are usually mild and go away by themselves.
• It usually takes a couple of weeks for carbamazepine to work.
• When taking carbamazepine for epilepsy, it’s best to stick to the same brand. If your usual brand is not available, talk to your doctor.

Carbamazepine can be taken by adults and children aged 1 month and over.

Carbamazepine is not suitable for some people. Tell your doctor before starting the medicine if you have:

• ever had an allergic reaction to carbamazepine or any other medicine in the past
• a heart condition
• a blood disorder called porphyria
• ever had problems with your bone marrow

Carbamazepine is a prescription medicine. It's important to take it as instructed by your doctor.

Dosage

How much you take will depend on what you are taking it for.

You'll usually start on a low dose of 100mg to 200mg, taken once or twice a day. This will be increased over several weeks to the usual dose.

The usual dose for:

• epilepsy – 800mg to 1200mg, taken as 1 or 2 doses
• nerve pain – 600mg to 800mg, taken as 1 or 2 doses
• bipolar disorder – 400mg to 600mg, taken as 1 or 2 doses

In children, the dose of carbamazepine will depend on the weight of your child. Your doctor will be able to prescribe the right dose for your child.

How to take it

If you take carbamazepine twice a day, try to space your doses evenly through the day. For example, first thing in the morning, and in the evening. You can take it with or without food.

Tablets – you can take tablets with or without food. Swallow the tablets whole with a drink of water. The tablets have a score line to help you break the tablet in half if you have difficulties swallowing the tablet whole.

Liquid – to take carbamezapine liquid shake the bottle before you measure out your dose. The medicine will come with a plastic syringe or spoon to help you measure out the right dose. If you don't have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give the right amount.

Suppositories – take the wrapping off and push a suppository gently into your anus. Read the instructions in the leaflet inside the package. They will explain how to use the suppository.

Will my dose go up or down?

To prevent the chance of side effects, your doctor will start you off on a low dose of carbamazepine. They will increase it gradually over a few days or weeks.

Once you find a dose that suits you, it will usually stay the same – unless your condition changes, or your doctor starts you on a new medicine that may affect carbamazepine.

What if I forget to take it?

If you take carbamazepine and miss a dose:

• once a day – take the missed dose as soon as you remember. If it's less than 12 hours before the next dose is due, it's better to leave out the missed dose and take your next dose as normal.
• twice a day – take the missed dose as soon as you remember. If it's less than 8 hours before the next dose is due, it's better to leave out the missed dose and take your next dose as normal.

Do not take 2 doses at the same time to make up for a forgotten dose.

If you have epilepsy, it's important to take this medicine regularly. Missing doses may trigger a seizure.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Ask your doctor for advice straight away. Taking too much carbamazepine can lead to serious side effects.

Call a doctor straight away if

Like all medicines, carbamazepine can cause side effects, although not everyone gets them.

Skin rashes

It's common to get a skin rash with carbamazepine. Most skin rashes are not serious.

However, if you notice a skin rash or redness, tell a doctor straight away, as this can develop into a life-threatening skin condition called Stevens-Johnson syndrome.

Stevens-Johnson syndrome is a rare side effect of carbamazepine. It causes flu-like symptoms, followed by a red or purple rash that spreads and forms blisters. The affected skin eventually dies and peels off.

It's more likely to happen in the first 8 weeks of starting carbamazepine, or when the dose is increased too quickly. It can also happen if carbamazepine is stopped suddenly for a few days and then restarted at the same dose as before, without reducing the dose and then increasing it slowly again.

Stevens-Johnson syndrome is more common in:

• children
• people who developed a rash with a different epilepsy medicine in the past
• people who are allergic to an antibiotic called trimethoprim
• people also taking a medicine called sodium valproate

To help prevent the chance of you getting a rash that could be confused with Stevens-Johnson syndrome, its best to not start any new medicines, foods or products during the first 3 months of treatment with carbamazepine.

It's also best to not start carbamazepine within 2 weeks of a viral infection, vaccination, or rash caused by something else.

Other common side effects

These common side effects may happen in more than 1 in 100 people. They're usually mild and go away by themselves.

Keep taking the medicine but talk to your pharmacist or doctor if these side effects bother you or do not go away:

• feeling dizzy, sleepy or tired
• feeling or being sick (nausea or vomiting)
• headaches
• dry mouth
• putting on weight

Serious side effects

It's unusual to have serious side effects after taking carbamazepine. Tell a doctor straight away if you have:

• unusual bleeding or bruising, mouth sores, infections, a high temperature or sore throat – these can be signs of a blood disorder
• thoughts of harming or killing yourself – a small number of people taking carbamazepine have had suicidal thoughts
• a severe rash with flushing, blisters or ulcers – these can be signs of Stevens-Johnson syndrome
• yellowing of skin or whites of eyes – these can be signs of a liver problem
• pain in your joints and muscles, a rash across the bridge of your nose and cheeks, and problems breathing – these are signs of lupus (systemic lupus erythematosus)

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to carbamazepine.

These are not all the side effects of carbamazepine. For a full list see the leaflet inside your medicines packet.

What to do about:

• feeling sleepy, dizzy or tired – do not drive or use tools or machinery if you're feeling this way. Try to avoid drinking alcohol as this will make you feel more tired. If you feel dizzy, stop what you are doing and sit or lie down until you feel better. As your body gets used to carbamazepine, these side effects should wear off. If they don't go after a few weeks, speak to your doctor.
• feeling or being sick – stick to simple meals and do not eat rich or spicy food while you're taking this medicine. It might help to take your carbamazepine after you've had a meal or snack. If you're being sick, try having small, frequent sips of water or squash to avoid dehydration. Do not take any other medicines to treat vomiting without speaking to a pharmacist or doctor.
• headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Talk to your doctor if headaches last longer than a week or are severe.
• dry mouth – try chewing sugar-free gum or sucking sugar-free sweets.
• putting on weight – try to eat a healthy balanced diet without increasing your portion sizes. Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods. Regular exercise will also help to keep your weight stable.

Carbamazepine and pregnancy

There's no firm evidence carbamazepine is harmful to an unborn baby. However, for safety, your doctor will only advise you to take it in pregnancy if the benefits of the medicine outweigh the risks.

It's important for you and your baby to stay well during pregnancy. If you become pregnant while taking carbamazepine, tell your doctor or nurse straight away. Do not stop taking it without talking to your doctor first.

If you have epilepsy, it's important that it's treated during pregnancy as seizures can harm you and your unborn baby.

Carbamazepine and breastfeeding

If your doctor or health visitor says your baby is healthy, carbamazepine can be taken while you're breastfeeding.

Carbamazepine does pass into breast milk. There have been some reports of side effects in breastfed babies, including sleeping more and not feeding well.

However, it's important to keep taking carbamazepine to keep you well. Do not stop taking it without talking to your doctor. Breastfeeding will also benefit both you and your baby.

If you notice that your baby is not feeding as well as usual, seems unusually sleepy, or if you have any other concerns about your baby, talk to your pharmacist, health visitor or doctor as soon as possible.

For more information about how carbamazepine can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPs) website.

There are some medicines that may interfere with the effects of carbamazepine.

Tell your doctor if you are taking any of these medicines:

• medicines for your heart such as warfarin, apixaban, rivaroxaban or diltiazem
• antibiotics or antifungals such as clarithromycin, erythromycin or fluconazole
• medicines used for depression or anxiety such as amitriptyline, citalopram or mirtazapine
• ciclosporin, tacrolimus or sirolimus – immunosuppressants used after transplant operations, but also sometimes to treat arthritis or psoriasis
• medicines used to treat HIV or AIDS such as dasubavir or ritonavir
• have taken medicines called monoamine oxidase inhibitors (MAOIs), used to treat depression – these can affect carbamazepine even if they've been stopped for a few weeks

Taking carbamazepine with painkillers

Carbamazepine can make strong pain killers such as tramadol, oxycodone and buprenorphine less effective.

Paracetamol and ibuprofen are safe to take with carbamezapine for a short time. Talk to your doctor if you need to take it for more than a few days.

Mixing carbamazepine with herbal remedies and supplements

Do not take St John's wort, the herbal remedy for depression, while you are being treated with carbamazepine. This is because St John's wort may make carbamazepine less effective.