Raynaud's phenomenon is an exaggerated vascular response to cold temperature and/or emotional stress that causes red, white, and blue color changes of the finger; and not the nail bed or fingertips.
Raynaud's phenomenon is not a numbness of the fingers when cold.
This is an example of what Raynaud's phenomenon looks like.
There are two kinds of Raynaud's phenomenon (RP): Primary and Secondary.
Primary RP is benign, or harmless, and tends to occur in young women. It is not associated with another condition.
Secondary RP is usually associated with another medical condition. Scleroderma, Lupus, Rheumatoid Arthritis, and dermatomyositis are come conditions that can be associated with it. It can also be due to medications, like Adderall.
Treatment is usually symptomatic: keeping core body warm. Medications that open up the blood flow to the hands may also be used, like amlodipine or nifedipine.