Anti-seizure medications: Relief from nerve pain

Anti-seizure (anticonvulsant) medications were developed primarily to reduce or control epileptic seizures. They also help control the type of stabbing or shooting pain sometimes caused by nerve damage. These drugs seem to work by quieting damaged nerves to slow or block uncontrolled pain signals.

Newer anti-seizure drugs typically have fewer side effects than do the older varieties, so they often are tried first. Newer anti-seizure drugs include:

• Gabapentin (Neurontin). Effective in preventing migraines, gabapentin's side effects include sleepiness, dizziness, diarrhea and mood swings.
• Lamotrigine (Lamictal). Rash is the most common side effect. Long-term use of lamotrigine can cause blurred vision.
• Tiagabine (Gabitril). Side effects include dizziness, fatigue, depression and confusion.
• Topiramate (Topamax). Also used to treat cluster headaches, topiramate can decrease the effectiveness of oral contraceptives. The drug also can prevent you from sweating and may increase your risk of kidney stones.

Older anti-seizure drugs have a longer history of use, so more is known about what types of pain each drug may be best suited to treat. Older anti-seizure drugs include:

• Carbamazepine (Carbatrol, Tegretol). Considered the best treatment for electric shock-like pain, carbamazepine is widely prescribed for trigeminal neuralgia — a nerve disorder that can feel like jolts of electricity running through your face. A newer form of this drug, called oxcarbazepine (Trileptal), has fewer side effects.
• Clonazepam (Klonopin). This drug is often used for headaches, temporomandibular joint (TMJ) dysfunction and phantom limb pain. Clonazepam's side effects include drowsiness and dizziness. It also may be habit-forming.
• Valproic acid (Depakote). When used for pain, this anti-seizure drug is primarily prescribed as a preventive treatment for migraine, cluster or tension headaches. Valproic acid can cause serious damage to the liver and a life-threatening inflammation of the pancreas.
• Phenytoin (Dilantin). Effective for migraines and facial nerve pain, phenytoin's side effects limit its present-day use. Long-term use can result in coarsening of the facial features, excessive hair growth, bleeding gums and numbness of the extremities.

Anti-seizure medications work by different mechanisms to achieve similar effects. You may be best served by taking two or more of these drugs simultaneously.

Pain caused by nerve damage can be disabling and difficult to control. Although much remains to be learned about how anti-seizure medications are effective against this type of pain, they sometimes provide relief when nothing else works.