性别不安症（Gender Dysphoria），原称性别认同障碍（Gender identity disorder，GID）是一个由心理学家和医生所定义的精神医学用语。

是指一个人在心理上无法认同自己的生理性别所引申的各项社会标签，相信自己应该属于其他性别。这是一种精神医学上的分类定义，通常是用来解释与变性、跨性别或异性装扮癖相关的情况。而在性别认同障碍也是最常应用在变性人的医学诊断上。

性别不安症最主要的症状是「性别躁郁」，是指对于自己本身的外显（生理）性别感到非常不舒服的情况。

在许多案例中性别不安症通常是在小时候就会出现，但也有在青春期或成人时才出现的可能，并且随着年纪增长而越来越强烈。由于许多文化并无法接受跨性别的行为，这种感觉往往为当事人以其家人、朋友带来许多问题。在许多案例的报告中，也有人的不适感是觉得自己的身体「出了差错」，或从一开始就不应该是如此。

Gender dysphoria or gender identity disorder (GID) is the formal diagnosis used by psychologists and physicians to describe people who experience significant dysphoria (distress) with the sex and gender they were assigned at birth. Evidence suggests that people who identify with a gender different from the one they were assigned at birth, may do so not just due to psychological or behavioral causes, but also biological ones related to their genetics, the makeup of their brains, or prenatal exposure to hormones.