Raynaud's phenomenon is a condition in which some areas of the body, usually the fingers or toes, have an exaggerated response to cold temperature or emotional stress. During an attack of Raynaud's, the blood vessels in the affected areas tighten, severely limiting the flow of blood to the skin.

Normally the body narrows (constricts) these blood vessels when the skin gets cold. This helps conserve body heat. Stress or exposure to cold temperatures may trigger an exaggeration of this normal body function. The fingers and hands (or, more rarely, the feet, nose, or ears) may turn pale, white, and later blue and feel cold to the touch. Sometimes fingers or toes feel numb and tingly, as if they have "fallen asleep," or they may become painful and swollen.

Most cases of Raynaud's phenomenon have no known cause. But some people may develop Raynaud's as a result of frostbite, an injury, or a disease (such as lupus, scleroderma, atherosclerosis, or rheumatoid arthritis). Vibrations from power tools or drugs that affect blood flow (such as nicotine, caffeine, and cold medicines that contain pseudoephedrine) may also trigger Raynaud's phenomenon.

Treatment for Raynaud's phenomenon focuses on preventing attacks by avoiding cold, stress, and other triggers. If your attempts to prevent attacks do not work, prescription medicine may be helpful.