Food Protein-Induced Enterocolitis Syndrome (FPIES): A Comprehensive Guide
Food Protein-Induced Enterocolitis Syndrome (FPIES) is a severe, non-IgE-mediated food allergy primarily affecting infants and young children. Often described as an "atypical food allergy," FPIES triggers gastrointestinal symptoms, including severe vomiting and diarrhoea, after ingestion of specific food proteins.
Despite its seriousness, FPIES remains frequently misdiagnosed due to its unique and varied presentations, e.g. delayed onset in symptoms and features such as profuse self-resolving vomiting.
Increasing awareness among parents and healthcare providers is critical for early identification and proper management.
Prof. Du Toit participated in a UK birth cohort (2001–2018) involving 158,510 children, of whom 214 cases were found to have FPIES, with a prevalence of ~0.14 %. The British Paediatric Surveillance system recorded an incidence of 0.006% during 2019–2020. In the US, 0.51 % of children and 0.22 % of adults had FPIES in 2015–2016.
FPIES Symptoms
Symptoms of FPIES typically begin shortly after ingesting the triggering food protein. Common symptoms include:
Severe and persistent vomiting BUT only 2-4 hours after ingestion, sometimes ending in bile-stained green vomit.
Vomiting, sometimes associated with diarrhoea.
Towards the end of the vomiting spells, lethargy and pallor (pale skin) may ensue, often described as a ‘rag doll’ appearance.
Dehydration is rare but possible. Shock (hypovolaemic shock in severe cases) is exceptionally rare.
These symptoms may mimic sepsis, seizures, or a cardiac event, often leading to confusion and delayed diagnosis. According to Allergy UK, approximately 20% of affected infants may initially receive an incorrect diagnosis.
For further insight into common allergic symptoms, our blog on food allergy symptoms in infants provides additional context.
FPIES Diagnosis
Accurate diagnosis of FPIES requires a careful evaluation of symptoms, a thorough dietary and clinical history, and the exclusion of other conditions.
Oral food challenges are required to assist with the diagnosis in some cases and will be needed to assess for resolution (which usually occurs within 1-3 years after the last symptoms).
Diagnostic Methods Include:
Comprehensive clinical evaluation
Oral food challenges under clinical supervision (considered the gold standard, unless the history is unequivocal)
We undertake controlled oral challenges to definitively diagnose FPIES, ensuring patient safety and accurate identification of triggers.
Common FPIES Triggers
Cow’s milk is the predominant trigger worldwide (35–67 % of cases) according to multiple studies. Soy reactions occur in 36–40 % of US infants. Fish, eggs, grains, fruit, or vegetables are also common, often depending on the region. FPIES triggers vary widely but typically include proteins from:
Cow’s milk (most common trigger, affecting approximately 50% of FPIES cases)
Root vegetables
Soy
Grains (oats, barley, rice)
Fish and shellfish
Eggs
Poultry
Awareness of these triggers significantly reduces the risk of recurrent episodes. Identifying these triggers often requires careful food diaries and supervised reintroduction by allergy specialists.
FPIES Rash and lack of Skin Manifestations
Gastrointestinal symptoms dominate.
FPIES does not typically cause transient rashes, unlike IgE-mediated food reactions.
Understanding FPIES Poop Changes
Stool characteristics in FPIES may involve frothy loose stools around the time of reactions. Blood in stool would indicate a separate non-IgE mediated condition, called food-induced colitis.
Stool Test Abnormalities in FPIES Reactions
Stool tests in FPIES are nonspecific but may show abnormalities during reactions.
Stool examination may reveal intact polymorphonuclear neutrophils or eosinophils, indicating gastrointestinal inflammation.
Continuation of Stool Test Abnormalities in FPIES Reactions
Reducing Substances:
Increased carbohydrates in stool may be detected, reflecting malabsorption due to intestinal inflammation, which should be short-lived.
Bloody or Mucousy Stools: only in food-induced colitis, usually milk-induced colitis.
Identifying FPIES Trigger Foods
Recognising trigger foods involves rigorous dietary tracking and supervised food reintroduction under medical guidance if needed.
Each case requires individualised care, often involving dietitians to manage nutritional needs and avoid deficiencies.
Food Protein Allergy vs FPIES
FPIES differs significantly from typical food protein allergies (IgE-mediated):
FPIES reactions are delayed (often 1–4 hours after ingestion)
No immediate respiratory or skin symptoms are associated (but these are typical in IgE allergies)
Requires different diagnostic and management strategies
Understanding these distinctions is crucial for appropriate medical intervention and dietary management.
Chronic FPIES
Chronic FPIES presents prolonged diarrhoea and poor growth due to continuous exposure to trigger foods, complicating diagnosis. This diagnosis should only be made after a thorough exclusion of more common and harmful chronic GI diseases.
Management involves careful dietary management, nutritional supplementation, and ongoing monitoring by allergy specialists to support growth and development.
Cow’s Milk Protein-Induced Enterocolitis (CMPIE)
Cow’s milk is among the most common triggers of colitis. This condition most commonly occurs in infants after exposure to cow's milk protein through breast milk or a cow's milk-based infant formula. Fresh blood is typically noted in the infant's stool, which rapidly resolves with maternal milk elimination (if breastfed) or switching to a modified cow’s milk formula.
In addition to blood in the stool, the infant may exhibit painful gastrointestinal symptoms, and the stools may be frothy and abnormal, containing flecks of fresh blood.
Cow's Milk protein enterocolitis requires complete avoidance, particularly in formula-fed infants. Alternative nutritional options, such as extensively hydrolysed or amino-acid-based formulas, are recommended under the supervision of a specialist.
Does FPIES Go Away?
Many children outgrow FPIES by the age of 3 to 5, especially with milk and soy triggers. Studies show that around 60-90% of children outgrow milk and soy FPIES by age 3. However, reactions to fish or shellfish may persist into adulthood, necessitating lifelong dietary caution.
Regular monitoring and carefully supervised food trials are essential for safely determining if and when trigger foods can be reintroduced.
Managing and Treating FPIES
Currently, there is no definitive cure for FPIES. Management strategies include:
Strict avoidance of trigger foods
Emergency preparedness (hydration and emergency treatment plans)
Nutritional support and guidance from dietitians
Regular medical follow-ups and growth monitoring
Educating caregivers on recognising early symptoms of reactions
Prompt medical intervention is crucial during acute reactions to prevent severe complications.
When to Seek Immediate Medical Attention
Parents and caregivers should seek immediate medical attention if signs of shock or severe dehydration occur:
Extreme lethargy or unresponsiveness
Severe, uncontrollable vomiting
Pale, clammy skin
Weak or rapid pulse
Our blog on what to do if your baby has an allergic reaction to food provides additional emergency response advice.
Expert FPIES Care at Our Clinic
Our allergy clinic, led by Prof George du Toit, a leading paediatric allergy specialist in London, specialises in diagnosing and managing FPIES. Prof du Toit’s extensive research and clinical expertise ensure patients receive cutting-edge care, including supervised oral food challenges, tailored dietary management, and detailed educational resources for families.
Resources and Support for Families
Families managing FPIES can access additional resources, peer support, and detailed information through organisations such as IFPIES, an international resource dedicated to improving outcomes for FPIES patients. Support groups and patient forums provide invaluable emotional support and practical guidance for daily management.
Families can find further reading on our blog, including ‘What to do if your baby has an allergic reaction to food’ and ‘Most common childhood food allergies’. Peer support groups like IFPIES UK provide vital emotional and practical guidance.
Conclusion
Understanding Food Protein-Induced Enterocolitis Syndrome (FPIES) is crucial for effective management and improved outcomes. Accurate diagnosis, careful dietary management, and expert medical support empower families to effectively manage this challenging condition. For specialised FPIES diagnosis and care, our clinic provides comprehensive services tailored to each patient’s needs.
For more information or to book an appointment, please contact us.
Frequently Asked Questions
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While FPIES reactions can be severe, prompt recognition and treatment significantly reduce risks.
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FPIES primarily affects children, but rare adult-onset cases have been reported, most commonly to shellfish
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FPIES is relatively rare, with precise prevalence uncertain due to frequent misdiagnosis.
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Yes, siblings of children with FPIES have a slightly increased likelihood of developing the condition.
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Exclusive breastfeeding does not eliminate risk of developing FPIES
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