异食癖（英语：Pica)，又称异食症、乱食症，主要表现于持续性地摄取非营养的物质，如泥土，肥皂或冰等。这类行为需持续一个月以上，并且在患者食用的物质被认为不适合其年龄应有的发展水平，才能被称为异食癖。不过在某些文化中，一些类似于异食癖的行为是传统习俗的一部分。这种疾病可导致儿童中毒，并阻碍其身心发育。除此之外，异食癖还可引起肠梗阻、营养不良和寄生虫病等。异食癖的病因尚不清楚，可能的解释包括矿物质缺乏症和精神异常等。异食癖在女性和儿童中更常见，特别是怀孕妇女、幼童及有发展障碍的人群，如自闭症患者。

Pica (/ˈpaɪkə/ PY-kə) is characterized by an appetite for substances that are largely non-nutritive, such as ice, paper, clay, drywall or paint, metal, chalk, soil, glass, or sand. According to DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition) criteria, for these actions to be considered pica, they must persist for more than one month at an age where eating such objects is considered developmentally inappropriate, not part of culturally sanctioned practice and sufficiently severe to warrant clinical attention. It can lead to intoxication in children, which can result in an impairment in both physical and mental development. In addition, it can also lead to surgical emergencies due to an intestinal obstruction as well as more subtle symptoms such as nutritional deficiencies and parasitosis. Pica has been linked to other mental and emotional disorders. Stressors such as emotional trauma, maternal deprivation, family issues, parental neglect, pregnancy, and a disorganized family structure are strongly linked to pica as a form of comfort.