Itch is an unpleasant cutaneous sensation which provokes the desire to scratch.Although it is the paramount dermatologic symptom, its pathophysiology remains an enigma.

• 瘙痒是一种具有强烈搔抓欲望并足以引起搔抓的感觉，是皮肤科最常见的症状,但是其病理生理机制并不明确。