In clinical studies, efficacy was demonstrated over a range of doses from 1,800 mg/day to 3,600 mg/day with comparable effects across the dose range; however, in these clinical studies, the additional benefit of using doses greater than 1,800 mg/day was not demonstrated. Overview: Gabapentin is used to treat certain people with seizures or nerve pain. Common side effects may include dizziness, sleepiness, or trouble with balance or coordination. Serious side. Gabapentin is available in 100 mg, 300 mg, and 400 mg capsules, and in 600 mg and 800 mg tablets. The dose of gabapentin to treat epilepsy with partial onset seizures in patients 12 years of age and older is up to 600 mg three times daily. Gabapentin is a prescription medicine used to treat seizures, pain after shingles, restless legs syndrome, and off-label uses. Learn about side effects, dosage, uses, warnings, interactions, and brand differences. Gabapentin is used to help control partial seizures (convulsions) in the treatment of epilepsy. This medicine cannot cure epilepsy and will only work to control seizures for as long as you continue to take it. Gabapentin is approved to prevent and control partial seizures, relieve postherpetic neuralgia after shingles and moderate-to-severe restless legs syndrome. Learn what side effects to watch for, drugs to avoid while taking gabapentin, how to take gabapentin and other important questions and answers.