Pica in Autistic Children: Causes, Investigations, and What Actually Helps

Pica — the persistent eating of things that are not food — is common in autistic children and almost never discussed honestly. Parents are often left managing it alone, and clinicians outside specialist settings may not know where to start with investigations or what to do beyond saying “try to keep things out of reach.”

This post sets out what the research actually tells us about why pica happens, what tests are worth doing and what they yield, what management approaches have evidence behind them, and where to find reliable video resources.

What counts as pica

Pica is defined in DSM-5 as the persistent eating of non-nutritive, non-food substances for a period of at least one month, at an age where this is developmentally inappropriate (generally over 2 years of age), and where the eating is not part of a culturally sanctioned practice (1).

The range of substances is wide: soil, sand, paint chips, paper, cardboard, fabric, stones, plaster, hair, foam, sponge, faeces, and many others. Some children eat only one type of material. Others are indiscriminate.

How common is it

Pica is much more prevalent in autistic children than in the general population. The most robust prevalence data comes from Fields et al. (2021), who assessed pica in over 2,000 preschool-aged children and found it in 23.2% of children with autism, compared to 3.5% of population-based controls (2). The rate was even higher — 28.1% — in children who had both autism and intellectual disability.

In autistic adults, estimates go higher still, with some studies reporting rates around 60%, particularly where intellectual disability is also present (3). Pica is also associated with increased severity of learning disability: the more significant the intellectual impairment, the higher the likelihood of pica.

These are not small numbers. In a typical autism diagnostic service, roughly one in four or five families will have some experience of pica.

Why it happens

Pica in autism is not a single behaviour with a single cause. Several factors contribute, and in most children, more than one is operating.

Sensory seeking. Many autistic children seek oral sensory input. The mouth is one of the most powerful sensory organs, and children who are seeking proprioceptive or tactile feedback may chew, mouth, or swallow non-food items for the sensation they provide. Certain textures — gritty, smooth, crunchy, or chewy — may be specifically sought. This is probably the most common contributing factor (4).

Inability to distinguish food from non-food. Some children with significant intellectual disability or developmental delay have not reliably acquired the concept that some things are food and some are not. This is particularly relevant in younger children or those with more severe cognitive impairment.

Nutritional deficiency. Iron deficiency and zinc deficiency are both associated with pica, and the relationship appears to be at least partly causal: correcting the deficiency sometimes resolves the pica. A 2019 randomised controlled trial in children with pica found that 80% of those receiving iron and zinc supplementation showed complete resolution, compared to the placebo group (5). This does not mean every child with pica is deficient, but it means every child with pica should be tested.

Behavioural function. In some children, pica serves a communicative or behavioural function: it may be maintained by attention (the response it provokes from adults), by escape (it ends a demand), or by automatic reinforcement (it feels good regardless of the social response). A functional analysis can clarify which of these is operating (6).

Anxiety and emotional regulation. Some children eat non-food items when anxious, bored, or distressed. It may function as a self-soothing behaviour, analogous to other repetitive behaviours.

Gut discomfort. There is some clinical — though limited research — evidence that children with chronic GI symptoms may engage in pica, possibly seeking substances that alter gut sensation or as a response to discomfort they cannot articulate.

Investigations: what to test and what you find

This is where clinical practice often falls short. Many children with pica are never investigated at all. The following tests have an evidence base and a reasonable yield.

Blood tests

Full blood count (FBC). Looking for microcytic anaemia (small red cells, suggesting iron deficiency) or other abnormalities. This is a basic screen and should always be done.

Ferritin. Serum ferritin is the best single test for iron stores. A low ferritin confirms iron deficiency even when the haemoglobin is still normal. In children with restricted diets — which includes many autistic children — ferritin is frequently low. A level below 15 μg/L is deficient; some authorities use a threshold of 20 μg/L in children (7).

Zinc. Plasma zinc can be measured, though it fluctuates with time of day and recent food intake. Despite this variability, testing is worth doing: zinc deficiency is more common in autistic children than in the general paediatric population, and supplementation in deficient children has been associated with resolution of pica in some studies (5).

Blood lead level. Children with pica are at substantially increased risk of lead poisoning, particularly if they eat soil, paint chips, or mouthing items with lead-containing surfaces. Shannon and Graef (1996) found that children with developmental disabilities and pica had rates of elevated blood lead levels several times higher than background population rates (8). Annual blood lead testing is recommended for autistic children with active pica, extending into adolescence.

Calcium, vitamin D, and phosphate. Worth checking particularly if the child eats plaster, chalk, or soil, which may indicate pica for calcium-containing substances.

Imaging

Abdominal ultrasound. A good first-line investigation when bezoar is suspected. Ultrasound can identify bezoars as echogenic masses with acoustic shadowing, it involves no radiation, and it is less invasive than other imaging — all of which matter in a child who may need repeated assessments over time. It is also more tolerable for children who find lying still for X-ray difficult.

Abdominal X-ray. Indicated if there is suspicion that the child has swallowed radio-opaque material (metal, stone, glass, batteries) or if there are acute symptoms suggesting obstruction — abdominal distension, vomiting, or worsening constipation. Non-radio-opaque items (fabric, hair, paper) will not be visible on plain film (9).

CT or endoscopy. Reserved for cases where there is clinical concern about obstruction or perforation that ultrasound and X-ray have not resolved, or where endoscopic removal of a bezoar or foreign body is needed.

What the tests yield

In clinical practice, the most commonly abnormal results in children with autism and pica are:

• Low ferritin (iron deficiency): found in a substantial proportion, particularly in children with restricted diets
• Low zinc: less consistently abnormal but worth checking
• Elevated blood lead: uncommon in UK settings but must not be missed, and more relevant in older housing stock
• Foreign bodies on abdominal X-ray: found intermittently and sometimes unexpectedly

The cost of these investigations is low. The cost of missing iron deficiency or lead exposure in a child who cannot report symptoms is high. There is no good reason not to check.

Management: what the evidence supports

Correct nutritional deficiencies

If iron or zinc are low, supplement them. This sounds obvious, but it is frequently overlooked. Iron supplementation in deficient children with pica has been shown to reduce or resolve pica in a proportion of cases. The 2019 RCT by Hagag et al. demonstrated complete resolution in 80% of iron/zinc-supplemented children (5). Even where pica does not fully resolve with supplementation, the child benefits from corrected nutrition.

In the UK, oral iron is the first-line treatment: ferrous fumarate or ferrous sulphate, prescribed according to BNFc dosing, typically for 3 months with a repeat ferritin to confirm repletion. Zinc supplementation should be guided by blood levels and the advice of a paediatric dietitian.

Environmental modification

This is not a formal “intervention” but it is the single most important safety measure. You cannot behaviour-manage a child out of eating a five-pence coin they have already swallowed.

Families should be supported to audit the home environment for commonly ingested items and to reduce access. Schools and respite settings should be informed and should do the same. The National Autistic Society uses the term “pica-proofing” and provides practical guidance on this (10).

This includes: removing small objects from the child’s reach, supervising outdoor play more closely (particularly near soil and sand), securing cleaning products and medications, and being alert to less obvious risks such as paint flakes in older buildings.

Behavioural approaches

Behavioural interventions have the strongest evidence base for reducing pica once medical causes have been addressed. Call et al. (2015) published treatment data from an intensive day-treatment setting and demonstrated clinically significant reductions in pica in the large majority of cases (6). A 2021 systematic review of behavioural treatments for pica in young people confirmed that several approaches have good evidence (11).

The key approaches are:

Functional analysis. Before choosing an intervention, work out why the child is engaging in pica. Is it sensory? Attention-maintained? Escape-maintained? Automatic? The answer determines the intervention. A clinical psychologist or behaviour analyst with experience in developmental disability should lead this.

Differential reinforcement. Reinforcing appropriate behaviours (keeping hands busy, choosing safe oral sensory items, communicating needs) while withdrawing reinforcement for pica. For example, if pica is attention-maintained, the adult response to pica becomes neutral, while the child receives attention for appropriate behaviour.

Blocking and redirection. Physically blocking access to non-food items and immediately redirecting to an alternative activity or safe oral substitute. This is often combined with differential reinforcement.

Discrimination training. Teaching the child to distinguish between things that are food and things that are not. This can use visual supports, sorting activities, and social stories. It is most effective in children with some language or symbolic understanding.

Sensory substitution

For children whose pica is primarily sensory-driven, providing safe alternatives that meet the same sensory need can reduce the frequency of pica. This might include:

• Chew toys designed for this purpose (e.g., Chewigem, ARK Therapeutic)
• Crunchy or chewy safe foods offered at regular intervals
• Textured toys for fidgeting
• A “sensory diet” designed with an occupational therapist

This does not eliminate pica in all cases, but it reduces the frequency in many, and it gives the child a legitimate way to meet the sensory need they are seeking.

Medication

There is limited evidence for pharmacological treatment of pica. Individual case reports have described improvement with SSRIs and with N-acetylcysteine, but there are no randomised controlled trials of any medication for pica in autism. Medication is not a first-line approach and should be considered only when other strategies have been tried and the behaviour remains dangerous.

Useful video resources

The following YouTube videos are from credible sources and provide accurate, practical information. I have watched all of them and checked their content against the published evidence.

Pica and Autism — Autism Research Institute (2023) Dean Alexander PhD discusses pica as a common form of self-injurious behaviour in autism, reviews prevalence data, the limitations of purely behavioural approaches, and the potential of biological interventions including nutritional assessment. Aimed at clinicians and informed parents.

Child with Autism Eating Dangerous Things: How to Stop Pica — Dr Mary Barbera (2020) Dr Barbera is a board-certified behaviour analyst and parent of an autistic child. Covers the causes of pica, practical safety steps, and an overview of assessment and intervention planning. Accessible for parents.

How to Manage Pica in Children with Autism — Olga Sirbu BCBA (2023) Nine practical strategies for managing pica, including environmental modification, sensory alternatives, nutritional assessment, and social stories. Well-structured and specific enough to be immediately useful.

Parenting a Child with Pica and Autism: Ollie’s Story — Attitude (2022) A parent’s perspective on managing severe pica in a significantly autistic child. Useful for families who feel alone with this and want to hear from someone who understands the daily reality.

When to refer and to whom

• Paediatric dietitian: for dietary assessment and supplementation guidance — especially if the child has ARFID or significantly restricted intake alongside pica
• Clinical psychologist or behaviour analyst: for functional analysis and behavioural intervention planning
• Paediatric gastroenterology: if there is abdominal distension, vomiting, or suspected bezoar/obstruction
• Community paediatrics or neurodisability: for initial medical workup and ongoing coordination
• Occupational therapy: for sensory assessment and sensory diet planning

In the UK, the GP or community paediatrician is usually the starting point. A blood test for FBC, ferritin, zinc, lead, calcium, and vitamin D can be arranged in primary care and does not require a specialist referral.

References

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 2013.
2. Fields VL, et al. Pica, Autism, and Other Disabilities. Pediatrics. 2021;147(2):e2020003624.
3. McAdam DB, et al. Variables affecting the food choices of adults with intellectual disability accessing residential services. Journal of Intellectual and Developmental Disability. 2004;29(3):249-263.
4. Matson JL, et al. A review of pica in individuals with intellectual disabilities. Research in Developmental Disabilities. 2013;34(4):1459-1469.
5. Hagag AA, et al. Role of iron and zinc supplementation in management of pica: a randomised controlled study on children with developmental disabilities. Journal of Tropical Pediatrics. 2019;65(4):399-405.
6. Call NA, et al. Clinical outcomes of behavioral treatments for pica in children with developmental disabilities. Journal of Autism and Developmental Disorders. 2015;45(7):2105-2114.
7. World Health Organization. Serum ferritin concentrations for the assessment of iron status and iron deficiency in populations. WHO/NMH/NHD/MNM/11.2. 2011.
8. Shannon M, Graef JW. Lead intoxication in children with pervasive developmental disorders. Journal of Toxicology: Clinical Toxicology. 1996;34(2):177-181.
9. Wyllie R. Foreign bodies in the gastrointestinal tract. Current Opinion in Pediatrics. 2006;18(5):563-564.
10. National Autistic Society. Eating — a guide for all audiences (includes pica). autism.org.uk/advice-and-guidance/topics/behaviour/eating/all-audiences.
11. McIvor M, et al. A systematic review of the effectiveness of behavioural treatments for pica in youths. Clinical Psychology & Psychotherapy. 2021;28(4):842-865.

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Dr Odet Aszkenasy is a Consultant Community Paediatrician and the author of The Genetics of Autism: A Guide for Parents and Professionals.