Anticonvulsants for chronic pain

Experts do not know exactly how anticonvulsants work to reduce chronic pain. They may block the flow of pain signals from the central nervous system.

Anticonvulsant drugs typically are used to control seizures in people who have epilepsy. These drugs may also be used to treat other painful conditions, such as postherpetic neuralgia and fibromyalgia.

Some anticonvulsant drugs may work better than others for certain conditions. For example, one small study showed lamotrigine to be effective in treating nerve-related pain related to some types of antiretroviral therapy in people with HIV.¹

Carbamazepine is approved by the U.S. Food and Drug Administration (FDA) to treat chronic pain from trigeminal neuralgia (sudden facial pain).²

Pregabalin (Lyrica) is approved by the FDA to treat chronic pain from postherpetic neuralgia and diabetic neuropathy. Studies show that pregabalin may reduce chronic pain in these conditions.³ It is also approved to treat fibromyalgia. Pregabalin may help relieve chronic pain, sleep problems, and fatigue in fibromyalgia.⁴

Even though gabapentin and pregabalin are the only drugs that have proved to help relieve some types of chronic pain, oxcarbazepine (Trileptal), lamotrigine (Lamictal), topiramate (Topamax), and zonisamide (Zonegran) may also be effective in reducing pain caused by diabetic neuropathy and postherpetic neuralgia. Long-term studies still need to be done to find out how well gabapentin, pregabalin, and other anticonvulsants help with chronic pain and to do comparisons with other types of medicines.

Common but temporary side effects may include dizziness, drowsiness, and fatigue. Tell your doctor if you think you are having side effects, which may include:

• Headache.
• Confusion.
• Skin rash.
• Nausea, vomiting, loss of appetite, or abdominal pain.
• Weight gain or weight loss.
• Swollen feet.

Do not suddenly stop taking an anticonvulsant. Your health professional will slowly reduce the dosage of this medicine so that you won't develop withdrawal symptoms such as anxiety, nausea, pain, sweating, and insomnia.

People of Asian ancestry may be at a higher risk for skin problems from taking carbamazepine. These skin problems, which include Stevens-Johnson syndrome and toxic epidermal necrolysis, can be dangerous. The FDA recommends that people of Asian background be tested before they take carbamazepine.

The U.S. Food and Drug Administration (FDA) has issued a warning on anticonvulsants and the risk of suicide and suicidal thoughts. The FDA does not recommend that people stop using these medicines. Instead, people who take anticonvulsant medicine should be watched closely for warning signs of suicide. People who take anticonvulsant medicine and who are worried about this side effect should talk to a doctor.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

Medicine will be started in low doses and then slowly increased until it effectively reduces your chronic pain.

Anticonvulsants are not safe for everyone. Be sure to tell your doctor about all medical conditions you have and other medicines you are taking to avoid side effects and complications.

Carbamazepine and lamotrigine may increase the chance of birth defects. If you are pregnant or thinking of getting pregnant, talk to your doctor before taking medicines.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

Citations

1. Simpson DM, et al. (2003). Lamotrigine for HIV-associated painful sensory neuropathies. A placebo-controlled trial. Neurology, 60(9): 1508–1514.

2. Drugs for pain (2004). Treatment Guidelines From the Medical Letter, 2(23): 47–54.

3. Pregabalin (Lyrica) for neuropathic pain and epilepsy (2005). Medical Letter on Drugs and Therapeutics, 47(1217): 75–76.

4. Crofford LJ, et al. (2005). Pregabalin for the treatment of fibromyalgia syndrome. Arthritis and Rheumatism, 52(4): 1264–1273.