What is Raynaud’s phenomenon? Raynaud’s phenomenon is a condition in which there are spasms, constriction and narrowing of the capillaries of the fingers and toes. Capillaries are tiny arteries, blood vessels that supply vital oxygen and nutrients to cells and tissues. A steady supply of oxygen and nutrients are critical to the health of the cells and tissues of the fingers and toes. Narrowing of the blood vessels that occurs in Raynaud’s phenomenon can lead to ischemia, which is a lack of blood flow to a part of the body. In ischemia, cells are unable to reproduce normally, recover effectively from injury, or fight infection. This can result in skin color changes, cold fingers and toes, and the development of sores or lesions that do not heal. Less commonly, Raynaud’s phenomenon can also affect the nose, lips and earlobes. When diagnosed early, Raynaud’s phenomenon can often be successfully treated before the development of complications. Left untreated , Raynaud’s phenomenon can lead to gangrene (tissue death) in some cases. Seek prompt medical care if you have symptoms of Raynaud’s phenomenon in the fingers or toes, such as unusual coldness, skin color changes, and the development of sores or lesions that do not heal.