This circulatory system disorder affects your fingers and occasionally your toes. It occurs when the small arteries that supply them with blood become extra-sensitive to cold and other factors that can produce narrowing and sudden spasm of the vessel. This reduces the flow of blood to the affected area. At first there is only a temporary spasm that can be eased by warmth, but the spasm may eventually recur more frequently.
Lack oxygenated blood makes the affected area of skin pale, often with a bluish tinge.
When a temporary spasm ends, blood flows back into the skin, and paleness disappears and is replaced by a flush. The disease may also occur as a secondary effect of conditions other than cold. It is sometimes an occupational disorder of people who work with vibrating equipment such as chain saws or pneumatic drills. It can be caused by a disorder of the connective tissue such as scleroderma, by pulmonary hypertension, by emotional disorder, or by a nerve disorder. And it can be caused by sensitivity to certain drugs that can affect blood vessels.