Carbamazepine stabilises nerve activity by preventing excessive electrical stimulation in the brain and was developed initially as a treatment for epilepsy. However it was realized that as carbamazepine stabilises electrical nerve activity, it could also be used to treat a condition called trigeminal neuralgia, in which the facial nerves spontaneously send messages of pain to the brain. Carbamazepine prevents the nerve signals being sent inappropriately and relieves the pain of this condition. It can also help in reducing the painful neuropathy experienced by people with diabetes.
Tegretol (carbamazepine) prevents the build-up of the electrical signals in the brain and reduces the release of a neurotransmitter called glutamate from the nerve cells. Glutamate acts as a natural 'nerve-exciting' agent. It is released when electrical signals build up in nerve cells and subsequently leads to increased activity in even more nerve cells. By reducing the release of glutamate, carbamazepine is thought to help stabilise the electrical activity in the brain.
In the case of trigeminal neuralgia, carbamazepine prevents the inappropriate sending of spontaneous pain messages to the brain from the facial nerves
and relieves the agony of this condition.
Usual Adult Dose for Trigeminal Neuralgia, initially 100 mg 1–2 times daily (but some patients may require higher initial dose), increased gradually according to response; usual dose 200 mg 3–4 times daily, up to 1.6 g daily in some patients.
Usual Adult Dose for Diabetic Neuropathy [unlicensed indication], initially 100 mg 1–2 times daily, increased gradually according to response; usual dose 200 mg 3–4 times daily, up to 1.6 g daily in some patients.
You should avoid drinking grapefruit juice whilst you are taking carbamazepine as it can enhance the effect of the drug.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
- Shaky movements and unsteady walk (ataxia).
- Allergic skin reactions.
- Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain.
- Double vision.
- Blurred vision.
- Decreased numbers of white and red blood cells and platelets.
- Dry mouth.
- Rectal irritation with suppositories.
- Fluid retention
- Weight gain.
- Abnormal involuntary movements (twitching or tics).
- Alteration in results of liver function tests.
- Speech disorders.
- Severe blistering skin reaction affecting the tissues of the eyes, mouth, throat and genitals (Stevens-Johnson Syndrome).
- Liver, kidney or heart disorders.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine please read the information provided with the medicine or consult your doctor or pharmacist.
Not to be used in:
- Problems with the electrical message pathways in the heart (atrioventricular block).
- History of decreased blood cell production by the bone marrow.
- Hereditary blood disorders called porphyrias.
- Allergy to tricyclic antidepressants, e.g. amitriptyline.
- People who have taken a monoamine-oxidase inhibitor antidepressant (MAOI) in the last 14 days.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Carbamazepine should be used with caution in:
- Mixed seizures including absence seizures.
- Elderly people.
- History of heart disease.
- History of kidney disease.
- History of liver disease.
- History of psychotic illness.
- Raised pressure in the eye (intraocular pressure), e.g. glaucoma.
- History of blood disorders that were caused by any other medication.
- History of previous carbamazepine therapy that was interrupted due to side effects or allergy.
Avoid drinking grapefruit juice whilst taking carbamazepine.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet