Milk Allergy in Infants and Young Children

Milk allergy is one of the commonest food allergies in infants and young children, with 2-3% of children under three years of age allergic to cow’s milk proteins, though most of them surpass this allergy.

Cow's milk allergy is basically an allergic reaction to one of the proteins in cow's milk that involves the immune system. 50% of these children seem to come out of it in the first year of life, another 25% during the second year and by 3 years of age, 80% outgrow this allergy.

Only a minority of them who still have cow's milk allergy at the age of three will continue to have this allergy in their adulthood. It has been found that a large number of children who are allergic to cow's milk also react to goat's milk and sheep's milk, and some are even allergic to the protein in soy milk.

Milk allergy and lactose intolerance are different

Lactose intolerance is not milk allergy. Lactose intolerance is different as it does not involve an immune response. It occurs when the digestive system fails to produce enough lactase enzymes to break down the lactose sugar in milk. Lactose intolerant individuals present with crampy abdominal pain, bloating, nausea and diarrhea. Also, it is rare in infants and more common among older kids and adults. Lactose intolerance can be ever-lasting or short-term especially following an intestinal illness, or even a round of antibiotics.

Symptoms of milk allergy

The symptoms of milk allergy may occur within a few minutes after exposure in immediate reactions, or after hours to several days in delayed reactions. The principal symptoms are gastrointestinal, dermatological and respiratory. The wide array of symptoms include    gastrointestinal symptoms (abdominal cramps, diarrhoea, vomiting, bloating) - affecting 50-60% of people with cow milk allergy; dermatological symptoms (rashes, including atopic dermatitis and eczema) - affecting 50-70% of people with cow milk allergy and respiratory symptoms (runny nose , wheeze, cough,) - affecting 20-30% of people with cow milk allergy.  In a very few cases, milk allergy can cause anaphylaxis and affect the infant's skin, stomach, blood pressure and breathing.

Most infants with milk allergy develop symptoms within the first few months of birth and it is usually rare for symptoms to start after the age of 12 months.

Anaphylaxis and its association with milk allergy

Rare cases of milk allergy present with a potentially severe and life-threatening allergic reaction (anaphylaxis) that affects several parts of the body and can lead to death. The foods most commonly associated with anaphylaxis are cow's milk, eggs, wheat, shrimp, fish, peanuts and other nuts. Children with severe milk allergy should avoid it strictly as even traces in cooked foods can cause allergic reactions and anaphylaxis.

Anaphylaxis usually occurs within seconds to minutes of exposure to an allergen and is a grave condition without emergency medical treatment. The presenting symptoms of an anaphylactic reaction include a tingling feeling, itching, or a metallic taste in the mouth. Other symptoms can include hives, irritation, warm feeling, wheezing or gasping, coughing, swelling of the lips and throat area, vomiting, diarrhea, abdominal cramping, fall in blood pressure, and loss of consciousness. These symptoms usually start within several minutes to two hours after the allergen exposure, but life-threatening reactions may worsen over a period of several hours.

Treatment of milk allergy

The treatment of milk allergy requires complete avoidance of milk proteins. Even yogurt, butter, cheese, and cream may also need to be avoided. Other species’ milk such as goat milk, sheep milk, mare milk etc. is not recommended for treatment of infants with cow milk allergy because these milks are nutritionally incomplete, are poor sources of certain vitamins (especially folic acid and vitamins B6, B12, C and D) and are only tolerated in a few infants with cow milk allergy.

If an infant suffers from milk allergy and is getting breastfeed, then it is imperative for the mother to restrict the amount of dairy products that she ingests because the milk protein that causes the allergic reaction can cross into the breast milk. Lactating mothers may even be required to follow an elimination diet. Alternative sources of calcium and other vital nutrients should be started to replace the nutrients that come from dairy products.

For formula fed infants, milk substitute formulas such as soy protein-based formula may be advised. If the infant is intolerant to soy, another option is available that suggests switching to a hypoallergenic formula. In this, the proteins are already denatured into smaller particles so that this formula becomes far less likely to stimulate an allergic response.

Please note that the formulas currently available in the market have been approved by the U.S. Food and Drug Administration (FDA) and have been formulated through a very specialized process that cannot be reproduced at home.

Major types of hypoallergenic formulas include:

1.    Extensively hydrolyzed formulas have cow's milk proteins are denatured into smaller particles so they're far less likely to cause allergy as compared to the whole proteins in regular formulas. Most allergic infants can tolerate these formulas, but in some cases, they still stimulate allergic reactions. The advantage of reducing allergenicity may be offset by the poor palatability of the resulting solution.

2.    Partially hydrolysed milk formula contains peptides large enough to cause allergic reactions and although they may be ideal as substitute milk for prevention of milk allergy in high-risk infants, they are not recommended for the treatment of cow's milk allergy.

3.    Amino acid-based infant formulas, containing protein in its simplest form – amino acids, may be recommended if baby's condition doesn't improve even after a switch to a hydrolyzed formula. They are usually palatable and well tolerated, but are very expensive.

Switching the infant to a different formula should result in the disappearance of symptoms in 2-4 weeks. It is recommended to continue with a hypoallergenic formula up until the baby's first birthday, and then cow's milk can be slowly introduced into his or her diet.

For children and adults, many commercially available replacements to milk are available. They include rice milk, soy milk, oat milk and almond milk, but they are not suitable nutrition for infants. Fruit juices supplemented with calcium are another alternative available for adults and children. If on an avoidance diet, it is important to take dietary advice as a replacement source of calcium may be needed to prevent the long term risk of calcium deficiency and osteoporosis.

Medications such as an epinephrine pen or an antihistamine such as diphenhydramine are prescribed by an allergist in case of accidental ingestion. Any person with potential anaphylaxis to a food should use their epinephrine pen immediately when any reaction happens on eating that food, in order to prevent anaphylaxis.