Carbamazepine
1 medicine
Carbamazepine is an anticonvulsant used for epilepsy, trigeminal neuralgia and bipolar disorder. It can trigger Stevens-Johnson syndrome, a severe skin reaction, so any new rash needs urgent medical review.
Key facts
- Carbamazepine (sold as Tegretol) is an anticonvulsant used for epilepsy, trigeminal neuralgia (a severe facial nerve pain condition), and some cases of bipolar disorder.
- You take it daily, usually split into two or three doses, with the dose raised gradually over several weeks to limit side effects.
- Carbamazepine can trigger Stevens-Johnson syndrome, a severe and sometimes fatal skin reaction. Any new rash needs same-day medical review. People of Han Chinese, Thai or other South East Asian ancestry carry the HLA-B*1502 gene variant, which raises this risk sharply and may be tested for before starting.
- Seek urgent care for a spreading or blistering rash, fever with sore throat, or yellowing of the skin or eyes.
What carbamazepine treats
Carbamazepine treats focal and generalised seizures in epilepsy. It relieves trigeminal neuralgia, a condition causing sudden severe facial pain, and nerve pain that can follow shingles. It is also used to stabilise mood in bipolar disorder. It does not relieve everyday headaches or general pain.
How carbamazepine works
Carbamazepine blocks sodium channels on nerve cells, making it harder for them to fire repeatedly. This calms the overactive electrical signals that cause seizures, quiets the misfiring nerve behind trigeminal neuralgia, and helps stabilise mood.
Before you take it
- Tell your prescriber if you have Han Chinese, Thai, or other South East Asian ancestry; genetic testing for HLA-B*1502 is recommended before starting because of the Stevens-Johnson syndrome risk.
- Avoid carbamazepine if you have a history of bone marrow problems or a previous serious skin reaction to it or a related medicine.
- Carbamazepine strongly induces liver enzymes, which speeds up the breakdown of many other drugs, including hormonal contraceptives (making them less reliable), warfarin, and some other anticonvulsants. Tell your prescriber and pharmacist about every medicine you take.
- Blood counts and liver function are checked before you start and at regular intervals during treatment.
Side effects
Common effects include drowsiness, dizziness, nausea, and blurred or double vision, especially when starting or increasing the dose.
Stop and seek urgent medical care for any of these:
- A new or spreading rash, blistering skin, or sores in the mouth.
- Fever, sore throat, mouth ulcers, or unusual bruising.
- Yellowing of the skin or eyes, dark urine, or severe abdominal pain.
- Swelling of the face, lips or tongue, or difficulty breathing.
Safety essentials
- Treat any new rash as an emergency until a doctor has assessed it: stop carbamazepine and get same-day medical review, since Stevens-Johnson syndrome can progress rapidly and be life-threatening. People of Han Chinese, Thai or other South East Asian ancestry face a higher genetic risk and may need testing first.
- Regular blood counts and liver tests are mandatory throughout treatment to catch rare but serious blood and liver toxicity early.
- Carbamazepine is a strong enzyme inducer and interacts with many common medicines; tell every prescriber and pharmacist you are taking it, including before starting hormonal contraception.
- Do not stop carbamazepine abruptly. Sudden withdrawal can trigger seizures, even if it is being used for pain or mood rather than epilepsy.
This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.