How Anticonvulsants Block Chronic Pain

If you've been suffering from certain types of chronic pain, you might be surprised to learn that an anti-seizure medication could help relieve your pain. 

Anticonvulsants, or anti-seizure medications, work as adjuvant analgesics. That means they can treat some types of chronic pain even though they are not designed for that purpose.

While the main use of anti-seizure medication is preventing seizures, anticonvulsants do appear to be effective at treating certain kinds of chronic pain. These include neuropathic pain, such as peripheral neuropathy, and chronic headaches, such as migraines.

Do Anti-Seizure Medications Help Chronic Pain?

Studies are being conducted on the effectiveness of anti-seizure medications for chronic pain. 

Some studies have suggested that other types of pain medication interventions should be investigated before anti-seizure medication is prescribed for chronic pain treatment, while others say that anticonvulsants are a mainstay of treatment and tend to have fewer long-term side effects. 

Only a few anti-seizure medications are FDA approved for chronic pain treatment, including carbamazepine (for trigeminal neuralgia) and gabapentin (for postherpetic neuralgia, or shingles pain).

The use of anti-seizure medication for other types of chronic pain is considered “off-label use,” as there have been few studies to investigate their effectiveness in long-term chronic pain management.

Commonly Used Anti-Seizure Medications for Chronic Pain

Here are some of the anti-seizure medications that are commonly used for pain management:

• Gabapentin (Neurontin): Gabapentin is approved for the treatment of lasting postherpetic neuralgia. It is also effective for treating diabetic neuropathy.
• Carbamazepine (Tegretol): Carbamazepine was traditionally the mainstay anti-seizure medication for neuropathic pain, especially for the treatment of trigeminal neuralgia (for which is it FDA approved). It's also effective for diabetic neuropathy pain and postherpetic neuralgia.
• Pregabalin (Lyrica): Pregabalin is a newer anti-seizure medication used for chronic pain, specifically pain associated with postherpetic neuralgia and diabetic neuropathy.
• Tiagabine (Gabitril): Tiagabine is an anti-seizure medication used in neuropathic pain associated with nerve injury, such as phantom limb pain.
• Topiramate (Topomax): Topiramate is an anti-seizure medication that is often used as a prophylactic migraine treatment. Prophylactics are taken to prevent pain rather than to control it once it starts.
• Valproic Acid (Depakote): Valproic acid is an anti-seizure medication that is used for migraine pain and may be effective at treating other types of nerve pain.
• Lamotrigine (Lamictal): Lamotrigine can be used to treat pain associated with trigeminal neuralgia as well as central pain syndromes, or stroke-related pain.

Other Anti-Seizure Medications and Chronic Pain

Because of the way they work on the nervous system, the following anti-seizure medications may also be useful in the treatment of chronic pain. Their effectiveness in chronic pain management, however, has not been studied thoroughly:

• Phenytoin
• Phenobarbitol
• Clonazepam
• Oxcarbazepine
• Zonisamide
• Levetiracetam

Potential Side Effects 

Anti-seizure medications have relatively few side effects when compared to other long-term pain medication use, though a few are worth mentioning.

The main side effects include:

• Drowsiness
• Dizziness
• Fatigue

Anti-seizure medications may also cause the following side effects:

• Constipation
• Nausea
• Confusion or trouble concentrating
• Loss of balance or trouble with coordination
• Double vision
• Slurred speech
• Rashes
• Loss of appetite
• Dry mouth

Remember: Medications affect everyone differently; your experience will be unique. If you have any concerns about taking anti-seizure medications for chronic pain, talk to your healthcare provider as soon as possible.