Acrocyanosis is a persistent blue discoloration of the entire hand or foot worsened by cold exposure. The hands and feet may be hyperhidrotic. It occurs chiefly in young women. Cyanosis increases as the temperature decreases and changes to erythema with elevation of the dependent part. It is differentiated from Raynaud's syndrome by its persistent nature (as opposed to the episodic nature of Raynaud), and lack of tissue damage (ulceration, distal finger tip resorption). Cyanosis may be idiopathic or caused by inhalation of butyl nitrite (acrocyanosis with swelling of the nose, ears, and dorsal hands), Interferone 2-alpha and anorexia nervosa (may improve with weight gain).