Pica

Clinical picture

• Ingestion of substances such as soil, clay, chalk, laundry starch, ice, paper, hair, paint chips, soap, cloth, or metal for a month or longer.
• The behavior is not culturally sanctioned in the patient's own context and is developmentally inappropriate, so it is not diagnosed before about age 2.
• Presentation is often through complications: iron deficiency anemia, lead poisoning, bowel obstruction, perforation, dental erosion, or parasitosis.
• Trichophagia can produce a trichobezoar, and Rapunzel syndrome extends the hair mass from the stomach through into the small bowel.
• In pregnancy, cravings for ice, clay, or laundry starch are common, frequently concealed, and rarely volunteered unless asked directly.
• In intellectual disability and autism, ingestion is often automatic and sensory-driven, occurring across settings and resistant to redirection.

Criteria snapshot

• Requires persistent eating of one or more nonnutritive, nonfood substances over a period of at least 1 month.
• The eating must be inappropriate to the individual's developmental level, which excludes normal mouthing behavior in infants and toddlers.
• The behavior must not form part of a culturally supported or socially normative practice within the person's own community.
• When it occurs alongside another mental disorder, intellectual disability, or pregnancy, it is diagnosed separately only if severe enough to warrant independent attention.
• Pica may be diagnosed together with anorexia nervosa or avoidant restrictive food intake disorder, and an in-remission specifier is available.

Neurobiology

• Iron and zinc deficiency are the most consistently reported associations, and repletion frequently resolves ice craving within days to weeks.
• Pagophagia responds to iron replacement faster than hemoglobin recovers, suggesting a direct iron-dependent central mechanism rather than anemia itself.
• Lead absorption is enhanced by iron deficiency, creating a feedback loop in which paint chip ingestion deepens the deficiency that drives it.
• Geophagia can bind dietary iron and zinc within the gut, worsening the deficiency and reinforcing the behavior independent of its origin.
• Dopaminergic reward pathways are implicated in animal models, and pica serves as the standard rodent proxy for nausea because rats cannot vomit.
• Complications include heavy metal toxicity, mercury and arsenic exposure, geohelminth and toxoplasma infection, and mechanical bowel injury.

Psychology

• In developmental disability, pica is typically maintained by automatic sensory reinforcement rather than by attention or by escape from demands.
• Functional analysis separates automatic, attention-maintained, and escape-maintained topographies, and directly dictates the intervention chosen.
• Neglect, understimulation, food insecurity, and institutional environments substantially raise both the risk and the frequency of ingestion.
• Stress, trauma, and obsessive-compulsive spectrum features contribute in some adults, with ingestion serving a self-soothing or ritual function.
• Caregiver responses that involve reprimanding or dramatically removing items can inadvertently reinforce attention-maintained ingestion.

Differential & comorbidity

• Distinguish from culturally sanctioned geophagia, from normal infant mouthing, and from nonnutritive ingestion during a psychotic episode.
• Exclude self-injury without ingestion, factitious disorder, and deliberate foreign body ingestion for secondary gain in correctional settings.
• Comorbidity centers on intellectual disability, autism spectrum disorder, schizophrenia, trichotillomania, and obsessive-compulsive disorder.
• Obtain CBC, ferritin, iron studies, zinc, and a blood lead level, plus abdominal imaging whenever obstruction or bezoar is suspected.
• Mortality risk comes from obstruction, perforation, and toxicity, so an acute abdomen in a patient with pica is a surgical question first.

Pharmacologic treatment

• No agent is approved for pica; correcting an identified deficiency is the closest thing to a specific and curative treatment.
• Replete with ferrous sulfate 325 mg once or twice daily, or with IV iron when absorption is poor, and recheck ferritin at 8 to 12 weeks.
• Supplement zinc where deficiency is documented, and treat identified geohelminth infection with albendazole or mebendazole.
• Chelation with succimer is indicated for blood lead levels at or above 45 mcg/dL, always alongside removing the environmental source.
• SSRIs and low-dose antipsychotics have case-report support only, and are reserved for comorbid OCD, psychosis, or severe self-injury.

Psychotherapy

• Applied behavior analysis guided by a functional analysis is the evidence base, particularly in intellectual disability and autism.
• Differential reinforcement of alternative behavior plus response interruption and redirection substantially reduces ingestion rates.
• Discrimination training teaches sorting of edible from inedible items, paired with reinforcement for consistently correct selection.
• Overcorrection and brief physical guidance are used sparingly and only within an approved behavior support plan with formal oversight.
• CBT with habit reversal suits cognitively intact adults, especially where trichophagia or ritualized ingestion is the presentation.

Adjunct options

• Environmental safety comes first: remove accessible nonfood items, secure cleaning products, and remediate lead paint within the home.
• Increase supervision and structured activity, since unstructured and understimulating time is when most ingestion episodes occur.
• Nutritional consultation addresses deficiency, food insecurity, and hunger-driven ingestion, all frequent contributors in practice.
• Dental and gastroenterology follow-up manages enamel erosion, bezoar removal, and recurrent obstruction in chronic cases.
• Screen household children when elevated lead is found, and involve public health for environmental testing and abatement.

Clinical pearls

• Not diagnosed under about age 2, and never when the practice is culturally sanctioned.
• Check ferritin and blood lead in every case; pagophagia often resolves with iron.
• Trichophagia plus an abdominal mass means bezoar until imaging says otherwise.