In Brief

Viagra may help with cold feet and hands

The erectile dysfunction (ED) drugs all work in pretty much the same way. They relax constricted blood vessels in the penis by inhibiting an enzyme (phosphodiesterase type 5) crucial to the complicated business of maintaining proper blood vessel "tone." The spongy erectile tissue in the penis swells when blood flows in through dilated (opened) blood vessels. The erection is maintained by swollen tissue pressing on veins so the blood can't escape.

People with Raynaud's syndrome also have a problem with uptight blood vessels: The small blood vessels that supply their feet and hands go into spasm, usually in response to cold or occasionally stress. Because blood can't get through, their fingers and sometimes toes become numb and painful. In severe cases, which usually involve connective tissue disease, Raynaud's can result in the death of tissue and complications like gangrene.