1. Erection problems  (Trust Mark: Doctor-Reviewed)
An erection problem is the inability to get or maintain an erection that is firm enough for a man to have intercourse. You may be unable to get an erection at all, or you may lose the erection during intercourse before you are ready. If the condit...• Reviewer: Louis S. Liou, MD, PhD, Assistant Professor of Urology, Department of Surgery, Boston University School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

2. Erectile dysfunction  (Trust Mark: Doctor-Reviewed)
Erectile dysfunction (ED) may be defined as the consistent inability to achieve or maintain an erection sufficient to permit satisfactory sexual intercourse. The word "consistent" is included in the definition because most men experience transient...• Author: Ralph Myerson M.D.