Pica (/ˈpaɪkə/ PY-kə) is the psychologically compulsive craving or consumption of objects that are not normally intended to be consumed. It is classified as an eating disorder but can also be the result of an existing mental disorder. The ingested or craved substance may be biological, natural, or manmade. The term was drawn directly from the Latin word for the Eurasian magpie, a bird subject to much folklore regarding its opportunistic feeding behaviors.

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), pica as a standalone eating disorder must persist for more than one month at an age when eating such objects is considered developmentally inappropriate, not part of culturally sanctioned practice, and sufficiently severe to warrant clinical attention. Pica may lead to intoxication in children, which can result in an impairment of both physical and mental development. In addition, it can cause surgical emergencies to address intestinal obstructions, as well as more subtle symptoms such as nutritional deficiencies, particularly iron deficiency, as well as parasitosis. Pica has been linked to other mental disorders. Stressors such as psychological trauma, maternal deprivation, family issues, parental neglect, pregnancy, and a disorganized family structure are risk factors for pica.

Pica is most commonly seen in pregnant women, small children, and people who may have developmental disorders such as autism. Children eating painted plaster containing lead may develop brain damage from lead poisoning. A similar risk exists from eating soil near roads that existed before the phase-out of tetraethyllead or that were sprayed with oil (to settle dust) contaminated by toxic PCBs or dioxin. In addition to poisoning, a much greater risk exists of gastrointestinal obstruction or tearing in the stomach. Another risk of eating soil is the ingestion of animal feces and accompanying parasites. Cases of severe bacterial infections occurrence (leptospirosis) in patients diagnosed with pica have also been reported. Pica can also be found in animals such as dogs and cats.

Pica is the consumption of substances with no significant nutritional value such as soap, plaster, plastic or paint. Subtypes are characterized by the substance eaten:

This eating pattern should last at least one month to meet the time diagnostic criteria of pica.

Complications may occur due to the substance consumed. For example, lead poisoning may result from the ingestion of paint or paint-soaked plaster, hairballs may cause intestinal obstruction, and Toxoplasma or Toxocara infections may follow ingestion of feces or soil.

Pica is currently recognized as a mental disorder by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). According to the DSM-5, mineral deficiencies are occasionally associated with pica, but biological abnormalities are rarely found. People practicing forms of pica, such as geophagy, pagophagy, and amylophagy, are more likely to be anemic or to have low hemoglobin concentration in their blood, lower levels of red blood cells (hematocrit), or lower plasma zinc levels. Specifically, practicing geophagy is more likely to be associated with anemia or low hemoglobin. Practicing pagophagy and amylophagy is more highly associated with anemia.

Mental health conditions such as obsessive–compulsive disorder (OCD) and schizophrenia have been proposed as causes of pica. More recently, cases of pica have been tied to the obsessive–compulsive spectrum, and a move has arisen to consider OCD in the cause of pica. Sensory, physiological, cultural, and psychosocial perspectives have also been used to explain the causation of pica.