Pica is the persistent craving and compulsive eating of nonfood substances. The Diagnostic and Statistical Manual of Mental Disorders, fifth edition, classifies it as a feeding and eating disorder.
The puzzling phenomenon of pica has been recognized and described since ancient times. Pica has been observed in ethnic groups worldwide, in both primitive and modernized cultures, in both sexes, and in all age groups. The word pica comes from the Latin name for magpie, a bird known for its unusual and indiscriminate eating habits. In addition to humans, pica has been observed in other animals, including the chimpanzee.
Pica in humans has many different subgroups, defined by the substance that is ingested. Some of the most commonly described types of pica are eating earth, soil, or clay (geophagia); ice (pagophagia); and starch (amylophagia). However, cases of pica involving dozens of other substances, including cigarette butts and ashes, hair, paint chips, and paper, have also been reported. In one unusual case, the patient ingested transdermal patches of fentanyl, an opioid medication given for severe pain. Eating the skin patch increased the patient's dose of the drug by a factor of 10.
Although pica can occur in individuals of any background, a higher incidence of pica is associated with:
Evidence suggests that there may be several causes of pica. One widely held theory points to iron deficiency as a major cause of pica. Several reports have described pica in individuals with documented iron deficiency, although there has been uncertainty as to whether the iron deficiency was a cause of pica or a result of it. Because some substances, such as clay, are believed to block the absorption of iron into the bloodstream, it was thought that low blood levels of iron could be a direct result of pica. However, some studies have shown that pica cravings in individuals with iron deficiency stop once iron supplements are given to correct the deficiency. Another study looked specifically at the rate of iron absorption during pica conditions and normal dietary behavior, and showed that the iron absorption was not decreased by pica. In addition, low blood levels of iron commonly occur in pregnant women and those with poor nutrition, two populations at higher risk for pica. Such findings offer strong support of iron deficiency as a cause, rather than result, of pica.
Other reports suggest that pica may have a psychological basis and may even fall into the spectrum of obsessive-compulsive disorder. Pica has a higher incidence in populations with an underlying diagnosis involving mental functioning. These diagnoses include psychiatric conditions like schizophrenia, developmental disorders including autism, and conditions with intellectual disability. These conditions are not characterized by iron deficiency, which supports a psychological component in the cause of pica.
Cultural and religious traditions may also play a role in pica behavior. In some cultures, nonfood substances are believed to have positive health or spiritual effects. Among some African Americans in the south, ingesting a particular kind of white clay is believed to promote health and reduce morning sickness during pregnancy. Other cultures practice pica out of belief that eating a particular substance may promote fertility or bring good luck.
The hallmark feature of pica, consistently consuming nonfood substances, often does not present publicly. People may be embarrassed to admit to these unusual eating habits, and may hide it from their family and physician. In other cases, an individual may not report the pica to a physician simply because of a lack of knowledge of pica's potential medical significance.
Amylophagia usually involves the consumption of cornstarch and, less frequently, laundry starch. The high caloric content of starch can cause excessive weight gain, while at the same time leading to malnutrition, as starch contributes “empty” calories lacking vitamins and minerals. Amylophagia during pregnancy can mimic gestational diabetes in its presentation and even in its potential harmful effects on the fetus.
Pica involving the ingestion of substances such as lead-based paint or paper containing mercury can cause symptoms of toxic poisoning. Compulsive consumption of even a seemingly harmless substance like ice (pagophagia) can have negative side effects, including decreased absorption of nutrients by the gut.
In order for the diagnosis of pica to be made, there must be a history of persistent consumption of a nonfood substance continuing for a minimum period of one month. Infants and toddlers are typically excluded from this diagnosis since mouthing objects is a normal developmental behavior at that age. Individuals with intellectual disability who function at or below an approximate cognitive level of 18 months may also be exempt from this diagnosis.
Pica is most often diagnosed when a report of such behaviors can be provided by the patient or documented by another individual. In other cases, pica is diagnosed after studies have been performed to assess the presenting symptoms. For example, imaging studies ordered to assess severe gastrointestinal complaints may reveal intestinal blockage with an opaque substance; such a finding is suggestive of pica. Biopsy of intestinal contents can also reveal findings, such as parasitic infection, consistent with pica. Pica may also be suspected if abnormal levels of certain minerals or chemicals are detected in the blood.
Pica in pregnant women is sometimes diagnosed after childbirth because of a health problem in the newborn caused by the substance(s) ingested by the mother. In one instance reported in Chicago, a newborn girl was treated for lead poisoning caused by her mother's eating fragments of lead-glazed pottery during pregnancy.
Treatment of pica will often depend on the cause and type of pica. Conventional medical treatment may be appropriate in certain situations. For example, supplementation with iron-containing vitamins has been shown to cause the unusual cravings to subside in some iron-deficient patients.
Medical complications and health threats, including high lead levels, bowel perforation, or intestinal obstruction, will require additional medical management, beyond addressing the underlying issue of pica.
Because most cases of pica do not have an obvious medical cause, treatment with counseling, education, and nutritional management is often more successful and more appropriate than treatment with medication. Some therapists specializing in eating disorders may have expertise in treating pica.
The prognosis for individuals with pica varies greatly, according to the type and amount of substance ingested, the extent of presenting side effects, and the success of treatment. Many of the side effects and complications of pica can be reversed once the behavior is stopped, while other complications, including infection and bowel perforation, pose significant health threats and if not successfully treated may result in death.
When seen in children, pica behavior tends to lessen with age. However, individuals with a history of pica are more likely to experience it again. Counseling and nutritional education can reduce the risk of recurrence.
There are no known methods of preventing pica. However, once pica is known or suspected, measures can be taken to reduce further ingestion of nonfood substances. Removing the particular substance from readily accessible areas can be helpful. Close observation of the individual with pica may limit inappropriate eating behaviors.
See also Cravings ; Eating disorders .
American Psychiatric Association. “Pica.” In Diagnostic and Statistical Manual of Mental Disorders: DSM-5. Arlington, VA: American Psychiatric, 2013.
Herrin, Marcia, and Nancy Matsumoto. The Parent's Guide to Childhood Eating Disorders. 2nd ed. Carlsbad, CA: Gurze Books, 2007.
Palmer, Robert L. Helping People with Eating Disorders: A Clinical Guide to Assessment and Treatment. 2nd ed. Chichester, West Sussex: Wiley Blackwell, 2014.
Porter, Robert S., ed. The Merck Manual of Diagnosis and Therapy. 20th ed. Whitehouse Station, NJ: Merck, 2018.
Woolsey, Monika M. Eating Disorders: A Clinical Guide to Counseling and Treatment. Chicago: American Dietetic Association, 2002.
Young, Sera L. Craving Earth: Understanding Pica—The Urge to Eat Clay, Starch, Ice, and Chalk. New York: Columbia University Press, 2011.
Grewal, Pardeep, and Brian Fitzgerald. “Pica with Learning Disability.” Journal of the Royal Society of Medicine 95, no. 1 (January 2002): 39–40.
Hamilton, S., et al. “Neonatal Lead Poisoning from Maternal Pica Behavior during Pregnancy.” Journal of the National Medical Association 93, no. 9 (September 2001): 317–19.
Kirschner, Jeffrey T. “Management of Pica: A Medical Enigma.” American Family Physician 63, no. 6 (March 15, 2001): 1177–78.
Liappas, I. A., et al. “Oral Transmucosal Abuse of Transdermal Fentanyl.” Journal of Psychopharmacology 18, 2 (June 2004): 277–80.
Moya, J., C. F. Bearer, and R. A. Etzel. “Children's Behavior and Physiology and How It Affects Exposure to Environmental Contaminants.” Pediatrics 113, no. S4 (April 2004): 996–1006.
Mycyk, M. B., and J. B. Leikin. “Combined Exchange Transfusion and Chelation Therapy for Neonatal Lead Poisoning.” Annals of Pharmacotherapy 38, no. 5 (May 2004): 821–24.
Williams, D. E., and D. McAdam. “Assessment, Behavioral Treatment, and Prevention of Pica: Clinical Guidelines and Recommendations for Practitioners.” Research in Developmental Disabilities 33, no. 6 (November–December 2012): 2050–57.
Nemours Foundation. “Pica.” KidsHealth.org . http://kidshealth.org/parent/emotions/behavior/pica.html (accessed April 16, 2018).
PubMed Health. “Behavioral Interventions to Reduce the Pica of Persons with Developmental Disabilities.” U.S. National Library of Medicine, National Institutes of Health. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0021593/ (accessed April 16, 2018).
American Academy of Child and Adolescent Psychiatry (AACAP), 3615 Wisconsin Ave. NW, Washington, DC, 20016, (202) 966-7300, http://www.aacap.org .
American Academy of Family Physicians, 11400 Tomahawk Creek Pkwy., Leawood, KS, 66211-2680, (913) 906-6000, (800) 274-2237, Fax: (913) 906-6075, http://www.aafp.org .
American Academy of Pediatrics (AAP), 141 Northwest Point Blvd., Elk Grove Village, IL, 60007, (847) 434-4000, (800) 433-9016, Fax: (847) 434-8000, http://www.aap.org .
American Psychiatric Association, 1000 Wilson Blvd., Ste. 1825, Arlington, VA, 22209-3901, (703) 907-7300, email@example.com, http://www.psych.org .
American Psychological Association, 750 1st St. NE, Washington, DC, 20002-4242, (202) 336-5500, TDD/TTY: (202) 336-6123, (800) 374-2721, http://www.apa.org .
Stefanie B. N. Dugan, M.S.
Rebecca J. Frey, PhD