Raynaud's phenomenon is a disorder characterized by spasm of digital arteries leading to blanching, coldness and discomfort of the affected digit, affecting up to 3-5% of the population at some time in their lives. Raynaud's is roughly classified into primary and secondary forms. The primary form may occur without apparent cause or following such things as acute trauma, repetitive vibrating trauma or frostbite. Secondary Raynaud's occurs in association with a variety of systemic immunological diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SS) and Sjogren's syndrome. Perhaps the most severe forms are associated with systemic sclerosis, less often in SLE where severe microvascular changes can lead to digital ulcerations which are difficult to heal and produce considerable functional impairment Treatment of Raynaud's has been a significant clinical challenge. The primary modality is to avoid cold exposure. Many drug classes have been shown to have some, but highly variable and potential toxicities.