Raynaud's syndrome is a medical condition primarily affecting the small blood vessels in the fingers and toes. It can also affect small blood vessels in other areas with reduced circulation, such as the nose, lips, or earlobes. The main triggers for this syndrome are cold weather, stress, and certain underlying medical conditions. Raynaud's syndrome causes the capillaries in the affected fingers or other body parts to constrict more than normal. This condition leads to oxygen deprivation in the affected areas, resulting in a change in skin color, first to white and then to blue.