Gabapentin comes as a capsule, a tablet and an oral liquid to take by mouth.Gabapentin is Used for chronic nerve pain .The dose should be reduced gradually each week . Symptoms of gabapentin include nausea, dizziness, headaches and anxiety. The safest way to stop using gabapentin is to taper off the medication under the supervision of a doctor. Never increase the dose even if you believe it is no longer effective.