拔毛癖是一种强迫行为，患者会有反复拔除头发、睫毛、胡须、鼻毛、耻毛、眉毛或其他体毛的冲动，有时会造成明显的光秃区块。拔毛癖在《精神疾病诊断与统计手册》第四版中分类为冲动控制疾患，但仍然有人对本疾病的分类存疑。拔毛癖有时看起来像是一种习惯、瘾、抽动症或强迫症。拔毛癖通常是从青少年时期开始的。沮丧或压力都有可能引发拔毛癖。受到社会大众的观念影响，患者往往会隐匿自己的病情，因而很难确切估计拔毛癖的盛行率；美国有250万人可能患有拔毛癖，盛行率约1%。

拔毛癖英文名“Trichotillomania”这个字来自希腊语的“tricho”（毛发）、“till(en)”（拔）和“mania”（狂热）。

Trichotillomania (/ˌtrɪkəˌtɪləˈmeɪniə/ TRIK-ə-TIL-ə-MAY-NEE-ə, also known as trichotillosis or hair pulling disorder) is an obsessive compulsive disorder characterized by the compulsive urge to pull out one's hair, leading to hair loss and balding, distress, and social or functional impairment. It appears in the ICD chapter 5 on mental and behavioural disorders, and is often chronic and difficult to treat.