1. About carbamazepine
Carbamazepine is a medicine used to treat epilepsy.
Carbamazepine is occasionally used to treat bipolar disorder when other medicines haven't 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).
2. Key facts
- 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.
- Carbamazepine is also called by the brand names Carbagen and Tegretol.
3. Who can and can't take it
Carbamazepine can be taken by adults and children aged 1 month and over.
Carbamazepine isn't suitable for some people. Tell your doctor before starting the medicine if you:
- have had an allergic reaction to carbamazepine or any other medicine in the past
- have a heart condition
- have a blood disorder called porphyria
- have had problems with your bone marrow
4. How and when to take it
Carbamazepine is a prescription medicine. It's important to take it as instructed by your doctor.
How much will I take?
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.
- 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 by accident can lead to serious side effects.
Urgent advice: Call a doctor straight away if you take too much carbamazepine and:
- feel sick or be sick (vomit)
- have breathing problems
- feel dizzy or sleepy
- have difficulty talking
- your vision is blurred
- have stomach pain
- feel confused, or your normal behaviour changes
- pass out
If you need to go to A&E, do not drive yourself - get someone else to drive you or call for an ambulance. Take the carbamezapine packet or leaflet inside it plus any remaining medicine with you.
5. Side effects
Like all medicines, carbamazepine can cause side effects, although not everyone gets them.
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:
- 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.
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 don't go away:
- feeling dizzy, sleepy or tired
- feeling or being sick (nausea or vomiting)
- 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.
Urgent advice: Contact a doctor straight away if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
These are warning signs of a serious allergic reaction. A serious allergic reaction is an emergency.
These are not all the side effects of carbamazepine. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect to the UK safety scheme.
6. How to cope with side effects
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.
7. Pregnancy and breastfeeding
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 carbamezapine, 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.
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.
Carbamazepine and breastfeeding
If your doctor or health visitor says your baby is healthy, carbamezapine 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 isn't 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.
8. Cautions with other medicines
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.
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.
Tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.
9. Common questions
How does carbamazepine work?
Carbamazepine is an anti-convulsant (or anti-epileptic) medicine. It works by stabilising the electrical activity in the brain and nerves.
For epilepsy, carbamazepine works by stopping electrical signals from building up in the nerve cells in the brain. It also reduces the release of a chemical (neurotransmitter) called glutamate. Too much glutamate can cause seizures.
For nerve pain, carbamazepine works by stabilising the electric signals in your nerves. This stops the pain signals being sent to your brain.
We don't fully understand how carbamazepine works for treating bipolar disorder. However, it's thought it reduces the glutamate activity in the brain.
How long does it take to work?
It can take 1 to 2 weeks for carbamazepine to work properly.
How long will I take it for?
If you have epilepsy or bipolar disorder, it's likely that once your condition is under control you will still need to take carbamazepine for several years.
If you have nerve pain, once the pain has gone you will need to take carbamazepine for several months to stop it coming back.
Is it safe to take for a long time?
Many people take carbamazepine safely for many months or years.
Your doctor can arrange for tests to check the strength of your bones. Regular exercise and a good diet can also help to keep your bones strong.
Are there similar medicines?
There are lots of other medicines that can be used for epilepsy but they work in different ways. They might have different side effects, or be taken more or less often.
If you have epilepsy, the choice will depend on the type of seizures that you have. Your doctor will discuss the best medicine for you.
If you have nerve pain or trigeminal neuralgia, other medicines that your doctor might use include phenytoin and gabapentin.
If you have low mood with bipolar disorder, other medicines your doctor might use include lithium or quetiapine.
How does carbamazepine compare with other medicines for epilepsy?
There are many different medicines for treating epilepsy.
It's not possible to say that one works better than the other. It varies from person to person and depends on the type of seizures and how often you have them.
Other epilepsy medicines include:
- sodium valproate
- valproic acid
To help to decide, your doctor will take into account your age and gender, the medicines you're already taking and any other health problems you may have.
It's usual to try to treat epilepsy using a single medicine. If this medicine isn't working well, or you're getting side effects, your doctor will generally try you on a different one.
If a single medicine isn't preventing your seizures, then your doctor may recommend taking 2 or more epilepsy medicines at the same time.
If carbamezapine is giving you side effects, or you're worried it isn't working for you, ask your doctor or specialist to recommend a different medicine.
How does carbamezapine compare with other medicines for nerve pain or trigeminal neuraligia?
Carbamazepine is usually the first medicine given to treat nerve pain or trigeminal neuralgia.
A medicine called phenytoin might be used if carbamazepine doesn't work or causes too many side effects.
Some other medicines may be used to treat nerve pain or trigeminal neuralgia, your doctor or specialist will find the medicine that works best for you.
How does it compare with other medicines for bipolar disorder?
If you have bipolar disorder, there are several types of medicine to prevent low mood. It's not possible to say that one works better than another and it varies from person to person.
Lithium is commonly used for treating low mood in bipolar disorder, as well as a medicine called quetiapine (an antipsychotic medicine).
Your doctor or specialist will find the medicines that work best for you.
Can I switch to a different medicine?
If you want to switch medicines, it's very important to do it exactly as your doctor tells you to.
Switching from carbamazepine to a different medicine will be different for each person.
If you want to switch, you'll usually start taking the new one at a low dose and slowly build up the dose while you are still taking carbamazepine. This protects you from seizures until the new drug starts to work.
Once you're taking the correct dose of the new medicine, you should be able to slowly reduce your dose of carbamazepine.
It can take several weeks or months until you've stopped taking carbamazepine completely.
Can I come off carbamazepine?
You are unlikely to get any extra symptoms when you stop taking this medicine.
If you take carbamazepine for epilepsy, you may have seizures once you stop taking it. You can prevent these withdrawal seizures by reducing the dose of your carbamazepine gradually.
However, if you are taking if for bipolar disorder or nerve pain, your condition could get worse for a short time after stopping it.
Do not stop taking carbamazepine, unless your doctor tells you to.
Can I take carbamazepine before surgery?
You can take carbamazepine as normal before and after surgery.
Carbamazepine may reduce the effects of some muscle relaxants so these may need to be increased.
Tell your doctor you are on carbamazepine if you need surgery.
Does it affect my fertility?
Carbamazepine does not affect female fertility, however, there have been rare reports of impaired male fertility. Speak to your doctor if you have any concerns.
Does it affect my contraception?
Carbamazepine might stop these contraceptives from working:
- combined hormonal contraceptives (the combined pill, patches, and vaginal ring). Look out for bleeding between periods, which might be a sign the pill isn't working. Talk to your doctor if this happens. Your doctor may advise you to use a different type of contraceptive, or condoms as well as combined hormonal contraception.
- progestogen-only contraceptive pill or implants. Your doctor may advise you to use a different type of contraceptive that is not affected by carbamazepine.
- emergency contraception - tell your doctor or pharmacist that you take carbamazepine if you need emergency contraception. You may need an increased dose or to use a coil.
Can I get epilepsy medicines for free?
If you have epilepsy, you're entitled to free prescriptions for all of your medicines (not just your epilepsy ones).
To claim your free prescriptions you'll need a medical exemption certificate.
The application form for the medical exemption certificate is called FP92A. You can get this from your doctor's surgery. You will need to fill in the form, then your doctor will sign it and send it off.
Can I drink alcohol with it?
Drinking alcohol while taking carbamazepine may make you feel sleepy or tired. It's best to stop drinking alcohol for the first few days, until you see how the medicine affects you.
If you do drink, try not to have more than the recommended guidelines of up to 14 units of alcohol a week. A standard glass of wine (175ml) is 2 units. A pint of lager or beer is usually 2 to 3 units of alcohol.
Are there foods and drinks I should avoid?
Do not drink grapefruit juice if you're taking carbamazepine. It increases the concentration of carbamazepine in your body and increases the risk of side effects.
Can I drive or ride a bike?
You may feel sleepy, tired or dizzy when you first start taking carbamazepine. This may also happen if your dose has increased. If you're affected, do not drive, ride a bike, or operate machinery until you feel more alert.
If you have epilepsy, you're not allowed to drive until you've had no seizures for 1 year.
You are also not allowed to drive for 6 months after you change your epilepsy medicine.