Flomax, also known as tomsulosin, is a common medication used to treat BPH, or benign prostatic hyperplasia. It does not cause erectile dysfunction, though it can cause related problems. In
rare cases, flomax can cause abnormal, prolonged or painful erection. If you do have an erection that is abnormally long (lasting longer than four hours) or painful, contact your doctor immediately. Your doctor may choose to discontinue flomax in lieu of other treatment options if this serious side effect occurs. Another less serious symptom that Flomax may cause is delayed ejaculation. In most cases, Flomax does not cause erectile dysfunction. However, these related side effects are possible.