Gabapentin is used to treat neuropathic pain, which can be caused by conditions such as diabetic neuropathy, postherpetic neuralgia (shingles-related pain), and various other neurological disorders. Gabapentin is available in various forms, including tablets, capsules, and an oral solution. It is usually taken by mouth. Common side effects of Gabapentin may include dizziness, drowsiness, fatigue, and difficulty with coordination.