Carbamazepine controls epileptic seizures, treats the severe facial pain of trigeminal neuralgia, and stabilises mood in bipolar disorder. It works well — and it interacts with more medicines than almost anything else in the pharmacy, including hormonal contraception.
What is Carbamazepine?
The South African Medicine Price Registry lists carbamazepine under many names, all Schedule 3 and mostly at 200 mg:
| Brands |
|---|
| Zeptol, Zecarb, Partid-200, Bio-Carbamazepine 200, Sandoz Carbamazepine, Degranol, Tegretol |
Controlled-release versions (marked CR) release the medicine more evenly, which reduces peak-related side effects such as dizziness and double vision. CR and standard forms are not freely interchangeable — switching between them should be a prescriber’s decision.
Carbamazepine stabilises overexcitable nerve cells by blocking voltage-gated sodium channels. Nerve cells fire by letting sodium rush in; carbamazepine binds preferentially to channels firing rapidly and repeatedly, damping runaway activity while leaving normal signalling largely intact.
That selectivity explains why one medicine treats three apparently unrelated conditions. A seizure is uncontrolled electrical firing in the brain; trigeminal neuralgia is a damaged facial nerve firing in bursts. Both are excessive nerve firing.
Two features shape treatment, and both cause confusion when unexplained:
It is started low and increased slowly. A full dose from the outset causes marked drowsiness, dizziness and double vision.
It speeds up its own breakdown. Carbamazepine induces the liver enzymes that metabolise it, so levels fall over the first weeks even on an unchanged dose. That is autoinduction, and it is why the dose is often increased again after a month — not because the condition has worsened.
What is Carbamazepine commonly used for?
- Epilepsy — focal (partial) seizures and generalised tonic-clonic seizures. A long-established first-line option.
- Trigeminal neuralgia — sudden, severe, electric-shock facial pain. Carbamazepine is the first-choice treatment, and it often works dramatically enough to be diagnostically useful.
- Bipolar disorder, as a mood stabiliser, particularly where lithium is unsuitable.
- Other nerve pain, including glossopharyngeal neuralgia and some diabetic neuropathy.
- Alcohol withdrawal, in some settings.
- Diabetes insipidus, occasionally, for an unrelated effect on water balance.
It is not for ordinary pain. Carbamazepine does nothing useful for headache, backache or injury. It targets nerve pain of a specific shooting, electric character.
It is a preventer. For epilepsy and neuralgia alike, it works by being taken consistently — not as a rescue treatment for a seizure or an attack in progress.
Do not stop it suddenly. In epilepsy, abrupt withdrawal can trigger prolonged or repeated seizures. Any change must be gradual and planned.
How Carbamazepine fits into this medicine category
| Group | Examples | Where it fits |
|---|---|---|
| Sodium channel blockers | Carbamazepine, lamotrigine, phenytoin | Focal and generalised seizures; trigeminal neuralgia |
| Broad-spectrum anti-epileptics | Sodium valproate, levetiracetam | Wider range of seizure types |
| Gabapentinoids | Gabapentin, pregabalin | Nerve pain; some seizure types |
| Mood stabilisers | Lithium, valproate, carbamazepine | Bipolar disorder |
| Tricyclics | Amitriptyline (Trepiline) | Nerve pain and depression |
| Sleep agents | Zolpidem and related | Short-term insomnia |
See the mental health and neurology medicines hub.
What to check before using Carbamazepine
Tell every prescriber and pharmacist that you take carbamazepine. It induces liver enzymes and therefore reduces the levels — and effectiveness — of a long list of medicines:
- Hormonal contraceptives. Carbamazepine makes the pill, patch, ring and implant substantially less reliable. This is a common cause of unplanned pregnancy, and anyone of childbearing age starting it needs a contraception discussion at the outset — usually a copper or hormonal IUD, or an injectable.
- Warfarin and direct oral anticoagulants.
- Other anti-epileptics, including lamotrigine and valproate.
- Antidepressants, antipsychotics and benzodiazepines.
- HIV medicines, including dolutegravir.
- TB medicines, statins, steroids, thyroid medicine, ciclosporin and many others.
Some medicines work the other way and raise carbamazepine levels dangerously — clarithromycin, erythromycin, fluconazole, ketoconazole, diltiazem, verapamil and grapefruit juice.
Also tell your doctor if you:
- Are of Han Chinese, Thai or other South-East Asian ancestry. The **HLA-B*1502** gene markedly increases the risk of severe skin reactions, and testing before starting is recommended in these groups.
- Have heart conduction problems, liver disease, kidney disease, a blood disorder, glaucoma or low sodium.
- Are pregnant or planning pregnancy. Carbamazepine carries a risk of birth defects. Do not stop it on your own — uncontrolled seizures are also dangerous — but plan this with a specialist, ideally before conception, along with folic acid.
- Are breastfeeding.
Practical points: take it with food; follow the titration exactly; keep your blood tests (levels, full blood count, liver function, sodium); and do not drive until stable and legally cleared.
Possible cautions and when to ask a pharmacist or doctor
Common effects, mostly early or after a dose increase, are drowsiness, dizziness, unsteadiness, double or blurred vision, nausea and headache. Most settle as the dose builds slowly.
Stop and get emergency help for any rash. Carbamazepine can cause severe reactions — Stevens-Johnson syndrome, toxic epidermal necrolysis and DRESS — which begin as an ordinary-looking rash. Warning signs:
- Any new rash, especially spreading
- Blistering or peeling skin, or sores in the mouth, eyes or genitals
- Rash with fever, swollen glands or facial swelling
Most rashes turn out minor. Because the dangerous ones start identically, the safe response is always to stop and be seen.
Also seek urgent advice for:
- Fever, sore throat, mouth ulcers, unusual bruising or bleeding — possible effects on blood cells.
- Yellowing of the skin or eyes, dark urine, or persistent abdominal pain.
- Confusion, marked drowsiness, headache with nausea, or new unsteadiness — carbamazepine lowers blood sodium, and this is how that presents.
- New or worsening depression, or thoughts of self-harm.
- More frequent or different seizures.
Contact your doctor before starting any new medicine, including over-the-counter products, and if you are planning a pregnancy or think you may be pregnant.
Related medicine guides
Frequently asked questions
What is carbamazepine 200 mg used for? Controlling epileptic seizures, treating trigeminal neuralgia, and stabilising mood in bipolar disorder. 200 mg is the standard tablet strength.
Is it a painkiller? Not in the usual sense. It treats the sudden, shooting, electric-shock pain of trigeminal neuralgia and some nerve pain, and does nothing for ordinary aches.
Does it stop the contraceptive pill working? Yes — it makes hormonal contraception significantly less reliable. Discuss an alternative method before relying on it.
Why was my dose increased after a month? Carbamazepine speeds up its own breakdown, so levels drop over the first weeks. An increase is usually expected rather than a sign of worsening.
Can I stop if I have had no seizures for a while? Not on your own. Stopping suddenly can trigger prolonged or repeated seizures. Any reduction must be planned.
What should I do if I get a rash? Stop taking it and seek medical attention the same day. Serious skin reactions begin as ordinary rashes.
Can I drink grapefruit juice? No. It raises carbamazepine levels and increases side effects.
Why so many blood tests? To check the drug level and monitor blood counts, liver function and sodium — all of which carbamazepine can affect.