What exactly is raynaud's syndrome?

Vessels constrict: Raynaud's phenomenon is a symptom caused by constriction of small blood vessels, usually in the fingers and toes, leading to a lack of nutrients and oxygen going to the fingers and toes. Raynaud's phenomenon can be due to auto-immune disorders, hormonal imbalances, medication effects, etc... A primary care doctor, endocrinologist, or rheumatologist can evaluate a person with such symptoms.

Painful extremities: In people with this syndrome exposed to the cold their toes and/or fingers will get painful and very pale. This is due to vasoconstriction of the small arterioles supplying blood into the fingers and toes which are overreacting to the cold by severely constricting, reducing blood flow. It usually resolves immediately with rewarding. It can indicate a systemic disease or be an isolated finding.