Erectile dysfunction (ED), also known as impotence, is a form of sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual activity. The most important physical causes of impotence are cardiovascular disease and diabetes, neurological problems, hormonal insufficiencies and drug side effects. Psychological impotence is where erection fails because of thoughts or feelings. Erectile dysfunction can have severe psychological consequences as it can be tied to relationship difficulties and masculine self-image.