Gabapentin may make you feel a little drowsy, dizzy, or clumsy when you first start taking it. You may feel like your thinking is slower. These are common side effects of gabapentin, but they usually get better as your body adjusts to the medication. These reactions are more common if you need to take a high dose. But if you do feel dizzy, unsteady or drowsy, avoid any activities — such as driving or operating machinery — that could be dangerous.