What is the most important information I should know about gabapentin (Neurontin)? You should not use this medication if you are allergic to gabapentin. Before taking gabapentin, tell your doctor if you have kidney, liver, or heart disease. You may have thoughts about suicide while taking gabapentin. Your doctor will need to check you at regular visits. Do not miss any scheduled appointments. Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, depression,