Malnutrition, Poor diet, or certain eating disorders, such as Anorexia Nervosa, Certain drugs and medications, such as hair growth drugs, Certain immunosuppressants, and Androgenic steroids, Cancer and cell mutation, Autoimmune and infectious diseases affecting the skin, Condition called porphyria cutanea tarda, which causes the skin to be extremely sensitive to UV light, may trigger hypertrichosis.