THE THERAPY OF PRURITUS

Technically, pruritus means itching without cutaneous manifestations of disease, but this article will hold to the wider use of the word as synonymous with itching, regardless of the presence or absence of visible alterations in the skin. Itching is so common a sensation as to be considered physiologic. Each one of us itches frequently and by the commonest of reflexes scratches or rubs, consciously or unconsciously. Slight itching is thereby allayed. Only when the sensation is not thus allayed but persists and becomes annoying is it considered pathologic. Little is known of its pathogenesis. The neurologists tell us that itching is a subpain sensation, a milder impulse traveling over the nerve pathway that transmits pain. The impulse must originate in the epidermis, however, for deeper irritations do not cause it and itching does not occur after the epidermis is removed. Whether itching is caused by any particular subpain impulse depends