Pruritus. Current concepts in pathogenesis and treatment.

Pruritus is an unpleasant sensation that provokes an urge to scratch. Many stimuli (notably histamine) are able to induce pruritus. The neural conduction of the itch sensation from the free unmyelinated nerve endings to the central nervous system mainly occurs on unmyelinated C fibres and the anterolateral spinothalamic tract. Pruritus is a common symptom in many skin or systemic diseases, but very little is known about the mechanism of the condition. Treatment evaluation is difficult; many methods do not evaluate the pruritus, but only the scratching, which is a consequence of pruritus. A number of asymptomatic treatments are only partially effective and we know little about their mechanism of action. Antihistamines remain the treatment of first choice for pruritus without known cause, but generally give incomplete relief. Whenever possible it is best to treat the underlying disease.