Trouble getting or keeping an erection seems like it’s just a sexual problem. For many men, though, it is much more. As described in What to do about Erectile Dysfunction, a Special Health Report from Harvard Medical School, erectile dysfunction is often an early warning sign of heart disease or other circulatory problems.

From a purely mechanical perspective, an erection is a hydraulic event — extra blood must be delivered to the penis, kept there for a while, and then drained away. An erection may not happen if something interferes with that blood flow. That something is often atherosclerosis, the accumulation of cholesterol-filled plaque inside arteries.

How atherosclerosis affects health depends on what tissue or organ the plaque-damaged artery nourishes. Plaque in a coronary artery can cause angina (chest pain with exercise or stress) or a heart attack. In an artery in the brain, it can cause memory loss, dementia, or stroke. Atherosclerosis in arteries supplying the penis can prevent the increase in blood flow needed to start or sustain an erection. In fact, blood vessel problems are the leading cause of erectile dysfunction. That’s why Harvard’s Dr. Michael P. O’Leary, the medical editor of the report, says that erections “serve as a barometer for overall health,” and that erectile dysfunction can be an early warning sign of trouble in the heart or elsewhere. That’s why it’s important for men to discuss this problem with their doctors.

Fortunately, simple lifestyle changes like losing weight, exercising more, or stopping smoking can help. Viagra and other erectile dysfunction drugs work for some men. Other men benefit from devices and sex therapy. The Erectile Dysfunction Special Health Report provides in-depth information about all these therapies, as well as information about the causes and diagnosis of erectile dysfunction, tips for talking to your doctor and your partner, and a special section on “Creating a better sex life.”