There are two types of allergic reactions to milk proteins: reactions involving immunoglobulin E (IgE) antibodies (IgE-mediated) and reactions not involving IgE antibodies (non-IgE-mediated). There are also some conditions that include both mixed IgE-mediated and non-IgE-mediated reactions.
IgE-mediated cow’s milk protein allergy
IgE-mediated cow’s milk protein allergies are rare but can cause anaphylaxis. Read about specific considerations for infants and children with IgE-mediated cow’s milk allergy here.
Non-IgE-mediated cow’s milk protein allergy
Non-IgE-mediated cow’s milk protein allergies (CMPA) are the most common milk allergies in infants and children, occurring in 2 per cent to 7.5 per cent of infants and young children and drops to less than 1 per cent of children by age 6. Non-IgE CMPA are classified into three categories. This article will focus on the three types of non-IgE-mediated allergic conditions caused by cow’s milk protein seen in infants and children:
- Food protein–induced allergic proctocolitis (FPIAP)
- Food protein–induced enteropathy (FPE)
- Food protein–induced enterocolitis syndrome (FPIES)
The cause of non-IgE-mediated cow’s milk allergy is not clearly understood, but it is more common in children with family members who have a history of allergies, eczema and asthma. The reactions are generally delayed, occurring hours after a child drinks milk. Parts of the immune system are activated by the proteins in cow’s milk, causing inflammation in the intestines. Symptoms vary between each of the three types and may include vomiting, diarrhea, poor weight gain, and blood and mucus in a child’s stool.
Food protein–induced allergic proctocolitis (FPIAP)
Food protein–induced allergic proctocolitis (FPIAP) due to cow’s milk protein is the most common form of non-IgE-mediated cow’s milk protein allergy.
Signs and symptoms
Infants or children with FPIAP often have blood and mucus in their stool. This can begin as streaks of blood at 2 to 8 weeks of age and can occur in both breastfed and formula-fed infants. Infants with FPIAP continue to feed well and gain weight. Symptoms are caused by inflammation in the rectum and in the last part of the colon called the sigmoid colon.
Diagnosis
FPIAP is diagnosed based on history and physical examination. There are no specific blood tests or other investigations that are required. The diagnosis is confirmed when a baby’s symptoms disappear after cow’s milk is removed from their diet.
Treatment
For formula-fed infants, cow’s milk formula should be replaced with a formula that is cow’s milk-free and extensively hydrolyzed (the proteins are broken down so they are easier to digest). Soy formula is not recommended because up to 50 per cent of infants with CMPA may also be allergic to soy protein.
Breastfed infants should continue breastfeeding, but breastfeeding parents are advised to remove all cow’s milk products and soy products from their diets. It takes at least two weeks for milk proteins in a breastfeeding parent’s diet to be eliminated from breast milk. A dietitian can help breastfeeding parents with a cow’s milk and soy elimination diet. If a breastfed infant still has symptoms after the parent changes their diet, the infant may be given a trial of a formula that is extensively hydrolyzed and cow’s milk-free.
It may take several days and up to two weeks after these diet changes for blood and mucus to disappear from a baby’s stool.
Long-term outcomes
Most children outgrow FPIAP between their first and second birthdays. Your child’s health-care provider will advise you on the best time and approach to reintroducing cow’s milk to them.
Food protein–induced enteropathy (FPE)
Food protein–induced enteropathy (FPE) due to cow’s milk protein is less common than FPIAP. In FPE, exposure to cow’s milk protein leads to inflammation of the small intestine.
Signs and symptoms
Infants with FPE often have diarrhea, poor weight gain and may have abdominal distention (swelling) and vomiting. Because of the inflammation in the small intestine, babies with FPE have difficulty absorbing nutrients.
Diagnosis
Infants and children in whom FPE is suspected will have blood and stool tests as well as an endoscopy and biopsy. During an endoscopy, a thin flexible tube with a camera on the end is inserted into the body to look at the small intestine. A biopsy involves taking small pieces of tissue from the small intestine to be examined under a microscope. These tests help identify problems with absorption of nutrients and anemia, and help exclude other conditions that can cause infant diarrhea and poor weight gain.
Treatment
For formula-fed infants, cow’s milk formula should be replaced with an amino acid formula. Soy formula is not recommended because up to 50 per cent of infants with CMPA may also be allergic to soy protein.
Breastfed infants should continue breastfeeding, but breastfeeding parents are advised to remove all cow’s milk products and soy products from their diets. It takes at least two to four weeks for milk proteins in a breastfeeding parent’s diet to be eliminated from breast milk and for the intestinal inflammation to heal. A dietitian can help breastfeeding parents with a cow’s milk and soy elimination diet. If a breastfed infant still has symptoms after the parent changes their diet, the infant may be given a trial of an amino acid formula.
It may take several weeks after these diet changes for the inflammation in the intestines to heal and for symptoms to improve.
Long-term outcomes
Most children outgrow FPE between their first and third birthdays. Your child’s health-care provider will advise you on the best time and approach to reintroducing cow’s milk to them.
Food protein–induced enterocolitis syndrome (FPIES)
Food protein–induced enterocolitis syndrome (FPIES) due to cow’s milk protein is a rare form of non-IgE-mediated cow’s milk protein allergy. There are acute and chronic forms of FPIES.
Signs and symptoms
Acute FPIES: Infants and children develop symptoms two to four hours after ingesting cow’s milk or cow’s milk protein–containing food. They usually have severe vomiting, pale skin, lethargy, sometimes diarrhea, and are at significant risk of dehydration. Symptoms last for a few hours.
Breastfed infants with acute FPIES often have milder symptoms.
Chronic FPIES: In some infants, symptoms are less severe and develop more slowly, with intermittent vomiting, diarrhea and poor weight gain.
Diagnosis
FPIES is diagnosed based on history and physical examination. There are no specific blood tests or other investigations that are required. In chronic FPIES, diagnosis is confirmed when a baby’s symptoms disappear after cow’s milk is removed from their diet (usually up to 10 days after a formula or diet change). Children with acute FPIES often have investigations done to check for other causes of severe illness, such as infection or bowel obstruction.
Treatment
Acute FPIES is considered a medical emergency. Immediate care in an emergency room involves intravenous (IV) fluids and medications.
Breastfeeding parents of infants diagnosed with FPIEs are advised to remove all cow’s milk products and soy products from their diets.
For formula-fed infants, cow’s milk formula should be replaced with a formula that is extensively hydrolyzed and cow’s milk-free. Soy formula is not recommended because up to 50 per cent of infants with CMPA may also be allergic to soy protein. Some infants who continue to have symptoms on extensively hydrolyzed formula may be switched to an amino acid formula.
Infants and children diagnosed with chronic FPIES require close monitoring of weight gain and nutrition after cow’s milk protein is removed.
Long-term outcomes
Most children outgrow FPIES by age 6. Reintroducing cow’s milk in children with FPIES can be considered under close supervision by a physician. This is often done as an oral food challenge.
When to see a health-care provider
Consult your child’s health-care provider if your child has blood or mucus in their stool, or if they develop diarrhea. Children with CMPA should have their weight and nutrition monitored by their health-care provider.
When to take your child to the nearest emergency department
Children with acute FPIES have sudden-onset and severe symptoms, including very frequent vomiting, diarrhea, pale skin and lethargy and are at risk of dehydration. If your child has these symptoms, bring them to a hospital immediately.
Resources
Food Allergy Canada — Common food allergens: Milk
References
Canadian Paediatric Society (June 25, 2024). Cow’s milk protein allergy in infants and children. Retrieved from https://cps.ca/en/documents/position/cows-milk-protein-allergy.
