Erectile dysfunction (ED) is the inability to get or maintain an erection, or achieve a satisfactory erection. ED affects millions of men. In the past decade, many medications have been introduced to treat ED, which is also known as impotence. However, it's important to know more about the condition before requesting a prescription from a doctor. Eighty to 90% of ED is caused by physical problems, usually related to the blood supply of the penis. Doctors can now diagnose and treat ED better because of a deeper understanding of the risk factors for the condition, which include: Type 2 diabetes Prostate problems Hypogonadism in association with a number of endocrinologic conditions Hypertension (high blood pressure) Vascular disease and vascular surgery High levels of blood cholesterol Low levels of HDL (high-density lipoprotein) Medications Neurogenic disorders Peyronie's disease (distortion or curvature of the penis) Priapism (inflammation of the penis) Depression Drinking alcohol Many chronic diseases, especially renal failure and dialysis Smoking, which intensifies the effects of other risk factors such as vascular disease or hypertension Age appears to be a strong indirect risk factor because of its link to many of the factors listed above. It is estimated that nearly 5% of men become impotent by the age of 40, and 15 to 25% by the age of 65. ED can be diagnosed in several ways. Medical/sexual history review: may reveal conditions or diseases that lead to ED and helps distinguish among problems with erection, ejaculation, orgasm, or sexual desire. Physical exam: will look for evidence of complications in the nervous system, hormonal issues, or circulatory problems. Also, unusual characteristics of the penis itself could suggest the basis of ED. Lab tests: include blood counts, urinalysis, lipid profile, and measurements of creatinine and liver enzymes. When low sexual desire is a symptom, measurement of testosterone in the blood can yield information about problems with the endocrine system. Psychosocial exam: can reveal psychological factors. The sexual partner also may be interviewed to determine expectations and perceptions encountered during sexual intercourse. The first line of treatment for ED is medication. Prominent ED medications that have been heavily advertised include sildenafil citrate (Viagra), vardenafil citrate (Levitra), and tadalafil citrate (Cialis). Men should not take these medications if they have a history of heart attack or stroke, or if they have a bleeding disorder or stomach ulcers. There are other treatment options for ED available, including hormone replacement therapy and several forms of penile implants. The loss of erectile capacity can have a profound effect on a man. The good news is that ED can usually be treated safely and effectively.