Raynaud's phenomenon is a blood vessel disorder. The condition is also called Raynaud's disease or Raynaud's syndrome.
When healthy people are in a cold environment, the tiny blood vessels in their skin constrict, or narrow. This is an effort by the body to conserve heat.
In people with Raynaud's phenomenon, that natural response to cold is exaggerated. The tiny blood vessels go into spasm, narrowing and reducing the blood flow to the affected areas. This response, called vasospasm, is seen most often in the fingers and toes. But it also can occur in the ears, cheeks and nose.
In some people, the constriction also can occur in response to emotional stress or a rapid change of temperature from warm to cool. Or, it may occur for no apparent reason.
The effect of this vasospasm can be dramatic and frightening. But it is temporary and rarely dangerous. Once the affected area is warmed, the blood vessels relax and expand. This allows more blood flow.
No one knows what causes Raynaud's phenomenon. People who do not have any other symptoms or disease are said to have primary Raynaud's. People who have Raynaud's as part of another disease are said to have secondary Raynaud's.
Secondary Raynaud's is commonly linked to connective-tissue disorders, such as scleroderma and lupus. It also can result from blood vessel damage due to injury, frostbite or use of jarring machinery, such as jackhammers or chainsaws.
Other causes of secondary Raynaud's include:
Medications (especially certain heart and migraine medications) and cocaine
Diseases that affect circulation (such as atherosclerosis)
These factors can also worsen pre-existing Raynaud's.