Pruritus can be a manifestation of a skin disease or a systemic disease. The main skin conditions that cause intense itching are scabies, lice, insect bites, urticaria, atopic dermatitis, lichen planus, prickly heat and herpes-like dermatitis. If the itching is pronounced but not accompanied by a rash, consider dry skin (more common in the elderly), systemic diseases, and drug reactions. Systemic diseases that can cause generalized pruritus include cholestatic diseases, uremic syndrome, true erythrocytosis and hematologic malignancies. Pruritus can also occur in women in late pregnancy. Barbiturates, salicylates, morphine, and cocaine can also cause it. Some of the diseases that may cause itching include hyperthyroidism, hypothyroidism, iron deficiency, and various types of cancer of the internal organs. Itching is rarely caused by psychological factors. To treat pruritus, older people choose older antihistamines with caution, as they can easily become overly sedated and cause falls. Other medications include doxepin, cloacenamide, naltrexone, nalmefene, sodium cromoglycate, and gabapentin. Ultraviolet light therapy is also available.