Patients taking gabapentin for occipital neuralgia may experience side effects. The common side effects include drowsiness, constipation, dizziness, dry mouth, unsteadiness, nausea, fatigue, weight gain, and vision changes. Serious side effects may also occur and if they do the patient should seek immediate medical attention and alert their doctor. The serious side effects include swollen legs and arms, shaking, tremors, mood and mental changes, loss of coordination, anxiety, abdominal pain, persistent fever, persistent cough and sore throat, red and painful legs or arms, abnormal bleeding and bruising, difficulty breathing, hearing loss, agitation, slow/fast/irregular heartbeat, rapid/pressured speech, and suicidal thoughts.