Carbamazepine

What is carbamazepine?

Carbamazepine is a prescription-only medicine classified as an anticonvulsant or antiepileptic drug. Also known by brand names like Tegretol and Curatil, it is used to treat various neurological and psychiatric conditions by reducing abnormal electrical activity in the brain and calming overactive nerve signals[1].  

What is carbamazepine used to treat?

Carbamazepine is commonly prescribed for[1]: 

• Epilepsy, to control seizures 

• Trigeminal neuralgia, which is a type of nerve pain affecting the face 

• Peripheral neuropathy caused by diabetes 

• Bipolar disorder, to help stabilise mood swings 

How does carbamazepine work?

 Carbamazepine works by stabilising hyperexcited nerve membranes, inhibits repetitive neuronal discharges and reduces synaptic transmission of excitatory impulses in the brain that cause seizures and pain. It stabilises the electrical activity in the brain and reduces the transmission of pain signals in nerve-related conditions[1].  

Who can take carbamazepine?

Carbamazepine can be taken by most adults and children. However, it may not be suitable for people who[1]: 

• Have had an allergic reaction to carbamazepine, similar medications or any of the ingredients listed as part of your medication  

• Especially with the presence of HLA-B*1502 allele, particularly in individuals of Han Chinese or Thai origin  

• Or he presence of HLA-A*3101 allele, particularly in individuals of European or Japanese origin 

• Have a history of bone marrow depression 

• Have liver disease (such as hepatic porphyria's) or certain heart conditions (AV block) 

• Are pregnant or breastfeeding (specialist advice is needed in these cases) 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is a typical dose of carbamazepine?

Carbamazepine comes in tablet, modified release tablet, liquid, and suppository form. The dosage of carbamazepine depends on the condition being treated. You’ll usually start on a lower dose which will be gradually increased over several weeks until you find the right dose for you. The usual dose for[1]: 

• epilepsy is 800mg to 1,200mg a day 

• nerve pain is 600mg to 800mg a day 

• bipolar disorder is 400mg to 600mg a day 

It is important to always follow the dosage instructions provided by your doctor or pharmacist.  

How do you take carbamazepine?

You should take carbamazepine with or after food to reduce the chance of stomach upset. Tablets should be swallowed whole with water, although some forms can be split in half along the scored line if necessary but check the Patient Information Leaflet for the manufacturers recommendation or consult your pharmacist beforehand. Use the syringe or spoon provided for the liquid form. Follow the instructions in the package for the suppository form. It is important to take the medication at the same times each day[1].  

Can you stop taking carbamazepine?

You should not stop taking carbamazepine suddenly without medical advice, as this can cause seizures or withdrawal symptoms. If you need to stop the medication, your doctor will guide you in gradually reducing the dose[1].  

What to do if you take too much carbamazepine?

Taking too much carbamazepine can be dangerous. Symptoms of overdose may include vomiting, drowsiness, confusion, seizures, increased heart rate and difficulty breathing. If you suspect an overdose or if you think you’ve taken too much, call emergency services immediately or go to the nearest accident and emergency (A&E) department and take your medication packet with you[1]. 

What to do if you forget a dose of carbamazepine

If you forget to take a dose, take it as soon as you remember unless it is almost time for your next dose. Do not take two doses at once to make up for a missed dose[1].  

Medicines you can and can’t take with carbamazepine

Carbamazepine interacts with many medicines, so it is important to inform your doctor or pharmacist about all other medications you are taking. It is known as a CY3A4 inducer, meaning it can increase the production of enzymes responsible for breaking down medicines thereby reducing their concentration and effectiveness. Some examples of interacting medicines include[1]: 

• Antibiotics such as erythromycin 

• Anticoagulants and blood thinners like warfarin 

• Antidepressants 

• Diuretics (water tablets) 

• Medications to treat HIV 

• Hormonal contraceptives, which may be less effective when taken with carbamazepine 

• Other epilepsy medications (e.g. brivaracetam) 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. Please note this is not a complete list, please see the Patient Information Leaflet for further information.   

Side effects of carbamazepine

The most common side effects include[1]: 

• Drowsiness or dizziness 

• Nausea or vomiting 

• Headache 

• Dry mouth 

The rarer, but more serious side effects, which require urgent medical attention, include[1]: 

• Skin rash or blistering 

• Yellowing of the skin or eyes (jaundice) 

• Unusual bruising or bleeding 

• Suicidal thoughts or significant mood changes 

It is important to seek immediate medical attention if symptoms such as fever, rash, mouth ulcers, bruising, or bleeding develop as they could be a sign of a serious adverse reaction 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include:

• Difficulty breathing

• Tightness in throat and chest

• Swelling of the tongue or throat

• Feeling faint or dizzy

• Blue/grey skin or lips

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about carbamazepine

Can I drink alcohol with carbamazepine? 
It is best to avoid alcohol because it can increase drowsiness and the risk of side effects[1].  

Can I drive on carbamazepine? 
Avoid driving until you know how carbamazepine affects you, as it can cause drowsiness or blurred vision, if this happens, do not drive or use tools or machines[1]. 

Is carbamazepine safe in pregnancy? 
Carbamazepine has an increased risk of congenital malformations during pregnancy, so discuss this with your doctor if you are pregnant or planning to become pregnant[1]. 

How long does carbamazepine take to work? 
The full effect of carbamazepine may take several days to weeks[1]. 

Do I require pre-treatment screening? 

It is recommended to test for HLA-B*1502 allele in individuals of Han Chinese or Thai origin, and consider testing in other at-risk Asian populations such as individuals of Filipino or Malaysian origin (avoid unless no alternative). 

Do I require any monitoring requirements? 

Your doctor may request routine blood tests to ensure treatment is effective and safe. Manufacturer recommends monitoring blood count, renal and hepatic function whilst taking carbamazepine.  

For the official NHS guide for carbamazepine, visit their website.