Unfortunately gabapentin can cause impotence.
Side effects of the Urogenital System:
Infrequent: urinary tract infection, dysuria, impotence, urinary incontinence, vaginal moniliasis, breast pain, menstrual disorder, polyuria, urinary retention
Rare: cystitis, ejaculation abnormal, swollen penis, gynecomastia, nocturia, pyelonephritis, swollen scrotum, urinary frequency, urinary urgency, urine abnormality.
Talk to your doctor about coming off gabapentin and he/she could put you on some other medicine to help the pain. You don’t have to ween off gabapentin but please get your doctor to monitor you once you are off.