Male impotence is the inability to maintain (or attain) a penile erection that is sufficient to permit sexual intercourse. It is distinguished from libido, which is sexual desire. The two function independently. Male impotence has many causes, and these increase in frequency with age. Difficulties with blood supply and neurologic changes are common causes of this dysfunction. Many drugs have impotence as a side effect as does alcohol. The problem requires a thorough evaluation. The best treatment is treatment of the underlying problem where possible.