Anti-seizure (anticonvulsant) medications were developed primarily to reduce or control epileptic seizures. But they can also help control the burning, stabbing or shooting pain sometimes caused by nerve damage. These drugs seem to work by slowing or blocking pain signals from damaged nerves.

Nerves can be damaged by many things, including injury, surgery, disease or exposure to toxins. For example, some people with diabetes develop numbness and pain (peripheral neuropathy) in their hands and feet. People who have shingles often continue to have pain (postherpetic neuralgia) after the shingles have cleared up.

This pain occurs because the damaged nerves are firing inappropriately and sending pain signals even though no tissue has been harmed. This type of pain can be debilitating and is often difficult to control.

The exact mechanism of action isn't fully understood, but anti-seizure medications appear to interfere with the overactive transmission of pain signals sent from damaged nerves.

Many anti-seizure drugs work in several different ways to block pain signals from damaged nerves. You may be best served by taking two or more of these drugs simultaneously.

Some anti-seizure drugs work particularly well for certain conditions. For example, carbamazepine (Carbatrol, Tegretol) 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.

Anti-seizure drugs have been used to treat nerve pain for more than 50 years, but their use is limited by the severity of side effects they produce.

Older anti-seizure drugs — carbamazepine, phenytoin (Dilantin) and valproic acid (Depakene) — can damage the liver. Other side effects include rash, nausea, vomiting, double vision, loss of coordination, drowsiness and headache.

Because these older drugs generally have more side effects than do the newer anticonvulsants, they often are used only when the newer medications prove ineffective. Despite the fact that they're older, they can be at least as effective as the newer drugs for pain relief.

Many new anti-seizure drugs have been developed in the past 15 years. Some have proved effective for relieving the pain caused by damaged nerves.

• Gabapentin (Neurontin)
• Lamotrigine (Lamictal)
• Pregabalin (Lyrica)
• Tiagabine (Gabitril)
• Topiramate (Topamax)

Gabapentin has the fewest side effects, so it typically is the first anti-seizure drug tried in people experiencing nerve pain. It's particularly effective in the treatment of postherpetic neuralgia, diabetic neuropathy and migraines.

As scientists learn more about the way anti-seizure drugs work, this information will be useful in determining which drugs may work best for what types of nerve pain. Pain caused by nerve damage can be disabling, but anti-seizure drugs sometimes provide relief when nothing else works.