Carbamazepine is one of the most widely used and effective medicines for epilepsy treatment. It can be used alone or with other seizure medicines to control complex partial seizures and secondarily generalized tonic-clonic seizures.
Carbamazepine has been used successfully for many years to treat trigeminal neuralgia, a specific syndrome of facial pain. It has been approved by the Food and Drug Administration (FDA) for that purpose. It may also be helpful in other specific pain syndromes.
Occasionally, carbamazepine is also used by patients with certain kinds of mental illness. Few studies have shown a definite benefit, however, and this kind of use is not approved by the FDA. It is, however, legal to prescribe medicines for "off-label uses" even though the FDA has not formally approved such uses.
Finally, some patients with a sleep disorder called Restless Legs Syndrome (a syndrome characterized by an uncomfortable sensation in the legs only relieved by movement) may be helped by carbamazepine.
Many people who take carbamazepine notice side effects upon starting the medication, therefore doctors usually start the medication at a low dose and gradually increase it over a few days. The most common complaints are usually related to high doses or increasing the medication quickly and include:
If you notice any of these problems and they are particularly troublesome, call the doctor. Sometimes the doctor can help by changing the amount or type of carbamazepine prescribed. No one should stop taking carbamazepine or change the amount they take without their doctor's guidance. Again, patients can expect to experience one or more of these symptoms when the drug is first started, but as it is slowly increased and as the body gets used to the drug, these uncomfortable effects usually disappear.
Approximately 5% to 10% of people who take carbamazepine develop a rash within the first month of taking it. The rash may be itchy, red, patchy, composed of small red bumps, and can be on any surface of the body, but like most drug rashes, are usually on the upper body, including the chest, back, neck and arms, and/or the legs. Any patient who notices a rash should call the doctor’s office and speak to the doctor or nurse, to be sure that the rash is not the beginning of a serious problem. If a patient notices blisters, lip swelling, or hives, he/she should not take the next dose of medication and call the doctor immediately to determine whether or not to go to the nearest emergency department. (Patients should never stop a seizure medication without calling the doctor’s office first as this can lead to uncontrolled seizures.)
Few people have serious reactions to carbamazepine, however anyone taking this medicine should be aware of these reactions. The most serious side effects from carbamazepine include blood abnormalities and liver problems.
Only about 1 in 30,000 people who take carbamazepine will develop a blood disorder, a risk that is slightly higher than it is for the general population. The doctor will probably recommend a complete blood count (cbc) test before starting carbamazepine. Then it will be possible to follow and recognize any changes that occur. Many people do have small changes in their blood counts that reverse on their own and are not dangerous.
If you notice any of these symptoms, call the doctor right away, but do not stop using carbamazepine without the doctor’s instruction.
Carbamazepine is also rarely associated with liver dysfunction. This can usually be checked by a physical exam with blood tests to evaluate the liver function (or liver function tests, “LFTs”). The first symptoms of a liver problem may be:
Tell the doctor right away if you notice any of these symptoms, but do not stop using carbamazepine without the doctor’s instruction.
Sometimes one kind of medicine changes the way another kind of medicine works in the body. This is true not only for prescription medicines, but also for over-the-counter medicines at the local drug store. It can also be true for herbal products, vitamins, a few kinds of food, and even cigarettes!
Any time a doctor suggests a new prescription, be sure to talk about what other medicines, vitamins and herbal remedies you are already using. If two kinds of medicine affect each other, the doctor may want to prescribe something else or change the amount to be taken.
Carbamazepine does interfere with several medications, including other antiepileptic medications, usually making them less effective. Some commonly used medications affected by carbamazepine are:
Importantly, carbamazepine can make oral contraceptives (birth control pills), hormonal injections and implants less effective. To prevent pregnancy, a woman using these methods may need to use a different type of birth control, raise the dosage of the contraceptive or change the frequency of the injection or implant. She should be sure to tell both the doctor prescribing contraception and the doctor prescribing carbamazepine about the other medicine so that the appropriate doses can be chosen. Carbamazepine does not affect barrier types of birth control, like condoms, non-hormonal IUDs, and diaphragms.
Additionally, other medications can affect carbamazepine, either driving the levels higher and increasing the chance for toxicity (increased side effects from high levels) or driving the levels lower and increasing the chance for breakthrough seizures. Usually, medications that affect carbamazepine cause the levels to drop, increasing the chance for breakthrough seizures.
Carbamazepine should generally be avoided in patients with primary generalized epilepsy (LINK) as it may worsen seizures in patients with this type of epilepsy, most commonly absence seizures or myoclonic seizures.
People with liver disease and those who take other medications should be cautious about taking carbamazepine. They should inform their doctor of liver disease, other medical conditions, and all medications they are taking to be sure that carbamazepine will be a safe antiepileptic choice.
Most people can take it successfully, however, if they work with the doctor to determine the correct amount to take.
In the United States, the Food and Drug Administration (FDA) assigns each medication to a "Pregnancy Category" according to whether it has been proven to be harmful in pregnancy. Carbamazepine is listed in Pregnancy Category D. This means that there is a risk to the baby, but the benefits may outweigh the risk for some women.
In fact, a large majority of women who use carbamazepine during pregnancy have normal, healthy babies. Certain types of defects are increased when carbamazepine is taken (especially during the first three months of pregnancy), but they are still relatively uncommon. The risk of defects is higher for women who take more than one seizure medicine and for women with a family history of birth defects.
All women of child bearing age should take at least 0.4 mg (400 mcg) of the vitamin called folic acid every day because it helps to prevent neural tube defects, the most common of which is spina bifida. These defects are more common in the babies of women who take carbamazepine during the first 4 to 6 weeks of pregnancy. Women with epilepsy taking any antiepileptic medication should take at least 1 mg of folic acid daily, though doctors may prescribe anywhere from 1-4 mg per day.
Some babies born to mothers taking antiepileptic medications have had inadequate blood clotting within the first 24 hours after birth. It is often recommended that the mother be given 10 to 20 mg of vitamin K per day during the last month of pregnancy to prevent this problem. Anywhere from 10-70% of carbamazepine in the mother’s blood passes through breast milk, however how much of this actually enters the baby’s bloodstream is not known. Further, how carbamazepine affects the baby is unknown. That said, it is strongly felt by neurologists and epileptologists that the benefits of breastfeeding largely outweigh the risks of exposing the baby to antiepileptic medications, including carbamazepine. As a matter of fact, the American Academy of Neurology and the American Epilepsy Society both recommend breastfeeding in women with epilepsy.