An antiepileptic (also used for nerve pain and bipolar disorder)
Carbamazepine
A long-established medicine for certain types of epilepsy and for trigeminal neuralgia (a severe facial nerve pain), also used in bipolar disorder — it interacts with many other drugs.
What is Carbamazepine?
Carbamazepine treats certain types of epilepsy, the severe facial nerve pain of trigeminal neuralgia, and is used in bipolar disorder. It calms overactive nerve signalling. It is a strong "enzyme inducer", meaning it speeds up the breakdown of many other medicines (including some contraceptives and anticoagulants), so interactions are important. It can also lower blood sodium and, rarely, cause serious skin reactions.
Education and reference only. This is a plain-language guide to Carbamazepine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Carbamazepine is a well-established medicine with several roles: it controls certain types of epileptic seizure (particularly focal seizures), it is the first-choice treatment for trigeminal neuralgia (a severe, electric-shock-like facial pain), and it is used as a mood stabiliser in bipolar disorder. It is taken as a long-term daily medicine, including a prolonged-release form that gives steadier levels. Its main practical challenge is that it interacts with a large number of other medicines.
How it works
Carbamazepine works mainly by stabilising overactive nerve cells: it blocks sodium channels that nerves use to fire, reducing the rapid, repetitive electrical activity that causes seizures and the shooting pain of trigeminal neuralgia. It also speeds up the liver enzymes that break down many medicines (it is an "enzyme inducer"), including itself — which is why its levels can change over the first weeks and why it lowers the levels, and effectiveness, of numerous other drugs.
What it treats
Conditions Carbamazepine is used for
Practical use
How to take Carbamazepine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it regularly as prescribed; the amount is usually built up slowly and levels settle over the first weeks.
- Do not stop suddenly — abruptly stopping an antiepileptic can trigger seizures; any change is made gradually with your doctor.
- Use reliable contraception and check it with your team, as carbamazepine can make hormonal methods fail; tell your team before any planned pregnancy.
- Have any new medicine (including over-the-counter and herbal products) checked for interactions.
- Report a new rash, fever, sore throat, mouth ulcers, unusual bruising, or marked drowsiness/confusion promptly.
Weighing it up
Advantages & disadvantages of Carbamazepine
Advantages
- Effective and well-proven for focal epilepsy and the first-line choice for trigeminal neuralgia.
- Also useful as a mood stabiliser in bipolar disorder.
- Prolonged-release tablets give steadier levels and can reduce side effects.
Disadvantages
- Interacts with a large number of medicines and reduces the reliability of hormonal contraception.
- Can lower blood sodium and, rarely, cause serious skin or blood reactions.
- Should be avoided in pregnancy where possible, and needs gradual dose changes.
Practical use
Good to know
Because carbamazepine speeds up the breakdown of many medicines, it can make hormonal contraception (the pill, patch and implant) less reliable and reduce the effect of drugs such as warfarin, DOAC anticoagulants and some others — always have new medicines checked and use a reliable, non-hormonal or higher-dose contraceptive method as advised. It can lower the blood sodium level (causing tiredness, headache or confusion) and, rarely, cause a serious skin reaction — people of Han Chinese or Thai background may be offered a gene test (HLA-B*1502) before starting because of a higher risk. Do not stop an antiepileptic suddenly, as this can trigger seizures. It should be avoided in pregnancy where possible.
Who should not take it / use with caution
- People with certain heart-conduction problems (such as some types of heart block) or a history of bone-marrow problems.
- People of Han Chinese or Thai family background without a gene test (HLA-B*1502), which identifies a higher risk of a serious skin reaction.
- Pregnancy where avoidable — it carries a risk to the developing baby; specialist advice is essential for anyone who might become pregnant.
Monitoring
- Blood sodium level, blood count and liver function (especially early on)
- For skin rash, particularly in the first weeks
- Seizure control or pain control; carbamazepine level when needed
Side effects
- Early on: drowsiness, dizziness, unsteadiness, double vision and nausea — often easing as the body adjusts and with slow build-up.
- A low blood sodium level (tiredness, headache, confusion) can occur, especially in older people.
- Rare but serious: significant skin reactions (widespread rash, blistering, fever) and effects on the blood count or liver — report a rash, fever, sore throat, mouth ulcers or unusual bruising promptly.
Key interactions
- It speeds up the breakdown of many medicines — reducing the effect of hormonal contraceptives, warfarin, DOACs, some other antiepileptics, and numerous other drugs.
- Some medicines (such as certain antibiotics and antifungals) raise carbamazepine levels and the risk of side effects.
- Alcohol adds to drowsiness; grapefruit juice can raise its level. Always have new medicines checked.
Available as: Standard tablets, prolonged-release tablets, chewable tablets, a liquid, and suppositories for short-term use when tablets cannot be taken.
Answers
Carbamazepine: frequently asked questions
Does carbamazepine stop the contraceptive pill working?
It can. Carbamazepine speeds up the breakdown of the hormones in many contraceptives (the pill, patch and implant), making them less reliable. If you could become pregnant, discuss a suitable method with your doctor — often a non-hormonal method such as a copper coil, or specific alternatives, is advised.
Can I stop carbamazepine if I feel better?
Do not stop it suddenly. Abruptly stopping an antiepileptic can trigger seizures, even if you have felt well. If it needs to change or stop, this is done gradually and under medical guidance.
Why might I need a blood test before starting?
People of Han Chinese or Thai family background are offered a gene test (HLA-B*1502) before starting, because it identifies a higher risk of a rare but serious skin reaction. Everyone on carbamazepine is also monitored for its effects on blood sodium, the blood count and the liver.
Is Tegretol the same as carbamazepine?
Yes — carbamazepine is the generic (active-ingredient) name and Tegretol is a brand name. For epilepsy, people are often kept on the same brand or version, because switching can slightly change blood levels.
Authoritative sources
- BNF: Carbamazepine.
- electronic Medicines Compendium (SmPC): Carbamazepine (Tegretol).
- NICE NG217: Epilepsies in children, young people and adults.
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