Gabapentin is an anti-epileptic medication, also called an anticonvulsant. It affects chemicals and nerves in the body that are involved in the cause of seizures and some types of pain. Gabapentin is used in adults to treat nerve pain caused by herpes virus or shingles (herpes zoster). The Horizant brand of gabapentin is also used to treat restless legs syndrome (RLS). The Neurontin brand of gabapentin is also used to treat seizures in adults and children who are at least 3 years old. Use only the brand and form of gabapentin that your doctor has prescribed. Check your medicine each time you get a refill at the pharmacy, to make sure you have received the correct form of this medication. Gabapentin may also be used for purposes not listed in this medication guide.