Food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis (FPIES) is a food allergy that mostly affects infants and young children. FPIES typically occurs in the first year of life. Symptoms are primarily gastrointestinal, including repetitive vomiting and sometimes diarrhea. Symptoms such as paleness and lethargy (fatigue) also may occur. FPIES does not cause symptoms commonly associated with other allergies (rash, congestion, runny nose, coughing, trouble breathing, anaphylaxis).

FPIES is a non-IgE (immunoglobin E)-mediated food allergy. How foods trigger symptoms and disease in FPIES is not fully understood. FPIES is thought to be caused by an immune reaction to the protein component of foods such as milk.

Cow milk is the most frequent FPIES trigger food throughout the world (including in the USA). Soy is a common trigger in the USA, but not in other parts of the world. Rice and oats are the most common solid food triggers in the USA. Common fruit and vegetable triggers in the USA include sweet potato, banana, and avocado. Common meat triggers include chicken and eggs.

If an infant or child is already consuming one of these higher-risk foods without any reactions, these foods should continue to be regularly included in the diet.

Symptoms usually develop after the first or second time the trigger food is eaten. Most children (50%–65%) only react to a single food; a smaller portion of children (5%–10%) react to three or more foods.

FPIES has two different forms: acute and chronic.

Acute FPIES reactions generally occur in children ages 4–12 months, 1–4 hours after ingestion of the trigger food. The primary symptom is profuse, repetitive vomiting. The child may appear tired and ill, with pale skin. Diarrhea may occur within 24 hours (most often 5–10 hours after ingestion). Severe cases can result in lower body temperature and low blood pressure.

Symptoms usually resolve within 24 hours, and children do not have symptoms between episodes. Children often have normal growth and do not have any symptoms between acute FPIES reactions. However, some children can have growth concerns and feeding difficulties, which can be addressed by a healthcare team.

Chronic FPIES is not well understood and is less common than acute FPIES. Chronic FPIES occurs in children under 4 months of age who are either on cow milk or soy protein formula. Chronic FPIES occurs with regular ingestion of the triggering food. Symptoms develop gradually and are not clearly related to feedings. For this reason, dietary triggers are often not recognized.

No deaths have been reported following a FPIES reaction, but admission to an intensive care unit may be required in severe cases.

Estimates vary widely on how common FPIES is, ranging from 7 to 14 in 1000 live births. Cases are increasing for unknown reasons. FPIES occurs slightly more often in males.

Commonly, children with FPIES have other family members with an allergic disease. FPIES may be associated with atopic conditions including eczema, asthma, food allergies, allergic rhinitis, and eosinophilic esophagitis.

FPIES can occur in adults but is rare and typically occurs with ingestion of seafood.

FPIES can be challenging to diagnose because symptoms such as vomiting and diarrhea may be mistaken for other diseases, such as viral infection. There is no specific test (blood tests, X-rays, or allergy tests) that can diagnose FPIES. Diagnosis of FPIES is based on the history of the child, provided by the parent, or by a healthcare professional observing a child during a FPIES attack. Physicians have specific criteria for diagnosing FPIES, including vomiting after ingestion of the suspected food, diarrhea, pale skin, lethargy, and low blood pressure.

Treatment of FPIES involves strict avoidance of trigger foods. This includes all forms of the allergen, including baked and processed foods. Most children with FPIES only react to one to two food triggers, so avoidance of multiple foods is usually not needed.

In most cases, if a mother is breastfeeding when the trigger food needs to be eliminated from the infant or child’s diet, the mother can continue to eat the trigger food. When supplementation of breast milk or infant formula is needed, use of a hypoallergenic formula is recommended in infants with FPIES triggered by either cow milk or soy formula.

How and where FPIES is treated depends on the severity of symptoms. Mild FPIES reactions involve 1–2 episodes of vomiting, with no additional symptoms (paleness or lethargy). Mild FPIES reactions can be managed at home with good fluid intake.

Moderate FPIES reactions involve more than three episodes of vomiting, with paleness and mild lethargy. These patients should be evaluated in an emergency department setting.

Severe FPIES reactions are defined as more than three episodes of vomiting, along with paleness, severe lethargy, and limpness. These patients require urgent evaluation, which may include hospitalization.

Many families find it helpful to have a letter from their gastroenterologist or allergist explaining FPIES and how an accidental ingestion should be treated when the child has a moderate to severe reaction.

Speak to your doctor or dietitian about introducing solids once your child is 4–6 months of age and showing signs of developmental readiness. Your healthcare practitioner can review lower-risk foods to start with (such as pumpkin, broccoli, peach, blueberry, parsnip) and how often to introduce a new food. In addition, your dietitian can help provide ideas for advancing texture in the diet to help your child progress with age-appropriate feeding skills.

If your child is having challenges with eating solids or aversion to spoon or finger foods, your doctor may recommend consultation with a feeding specialist, typically a speech language pathologist or occupational therapist.

Acute FPIES resolves within 4–12 hours of eliminating the trigger food. Chronic FPIES resolves within 3–10 days of eliminating the food. Children with FPIES typically outgrow their allergy by 3–5 years of age.

Food challenges to determine whether a child has outgrown their allergy should not be done at home. An oral food challenge (OFC) should be conducted in either the clinic or hospital setting under the guidance of a physician to determine if a child has outgrown their FPIES reaction.

The International FPIES Association is an international non-profit organization dedicated to improving the diagnosis, treatment, and quality of life for those with FPIES. Educational information provided by this association is reviewed by a medical advisory board.

Author: Anil Kesavan MD, Rush University Medical Center
Editor: Athos Bousvaros MD, Boston Children’s Hospital
June 2021