Milk allergy

What is cow’s milk allergy?

Cow’s milk and cow’s-milk-containing foods (called dairy products) can cause reactions when eaten. This is because either a) the affected individuals are allergic to the proteins in cow’s milk (cow’s milk protein allergy), or b) they cannot digest the sugar (lactose) in the milk (lactose intolerance).

This information is for individuals with cow’s milk protein allergy.

Cow’s milk allergy is common in infants and young children, usually developing before six months of age. It affects about one in 50 infants, but is much less common in older children and adults, as most affected children will grow out of their allergy. However, in a small minority of individuals, milk allergy is lifelong.

The presenting symptoms of cow’s milk protein allergy are usually more widespread and can involve the skin, respiratory system, gut, and circulation. The symptoms of lactose intolerance affect only the gut with stomach ache, bloating, and diarrhoea.

Cow’s milk allergy is common in infants and young children, usually developing before six months of age. It affects about one in 50 infants, but is much less common in older children and adults, as most affected children will grow out of their allergy. However, in a small minority of individuals, milk allergy is lifelong.

The proteins in cow’s milk are similar to those in more closely related animals (such as goats, sheep, buffalo) than less closely related (donkeys, horses, camels). As allergy is a reaction against the proteins in cow’s milk, individuals who are allergic to cow’s milk will also be allergic to goat’s milk.

Heating does not change the allergic potential of cow’s milk; so allergic individuals will also react to boiled milk. However, when milk is baked with wheat, binding between the milk and wheat hides the milk proteins, thereby reducing its allergic potential. Individuals allergic to cow’s milk will often be able to tolerate baked milk in cakes and biscuits before they can tolerate fresh or raw milk. Your allergy team will be able to let you know if you are likely to tolerate baked milk, and give you advice on how to introduce this.

What are the symptoms of cow’s milk allergy?

In infants, cow’s milk allergy can present broadly in one of two ways, either with the typical immediate symptoms of food allergy involving the skin, respiratory system, gut, and (rarely) circulation where onset follows soon after ingestion (within two hours) or with delayed mostly gut symptoms or eczema flare (up to 72 hours later).

The typical immediate-onset (also called IgE mediated) symptoms include rash, itching, and swelling which can spread all over the body; runny nose, sneezing, and itchy watery eyes; coughing, wheezing, and trouble with breathing; choking, gagging, vomiting, stomach cramps, and diarrhoea; pallor and drowsiness.

In most children, allergic reactions to cow’s milk are generally mild to moderate. Rarely, the reaction may progress to the more severe symptoms of pallor, drowsiness and loss of consciousness due to a fall in blood pressure termed anaphylaxis. Delayed-onset symptoms are by their nature more difficult to identify as being caused by cow’s milk allergy because they can occur two to 72 hours, or even days, after milk ingestion and because they often resemble common ailments in infancy such as colic, reflux, and constipation. These symptoms include vomiting, nausea, abdominal cramps, diarrhoea and difficulty in passing stools. Cow’s milk allergy should be considered in infants who respond poorly to the medical treatment for these symptoms and who in addition may be particularly irritable, refuse feeds, experience difficulty swallowing or are exhibiting faltering growth.

Milk allergy can also be an important factor in infants and children with moderate to severe eczema, particularly where the eczema does not respond to adequate treatment with moderate strength topical steroids and regular moisturizing creams. These children can present with acute skin symptoms (hives, itch, and swelling) in addition to their eczema or with worsening of the eczema itself.

How is cow’s milk allergy diagnosed?

The diagnosis of cow’s milk allergy in immediate-onset symptoms is based on the combination of history of a previous reaction confirmed by allergy skin tests or blood tests. As these tests are commonly negative in delayed-onset cow’s milk allergy or where cow’s milk allergy is associated with eczema, diagnosis in these cases can only be confirmed by symptomatic improvement following dietary exclusion of cow’s milk.

Will the allergy resolve?

Cow’s milk allergy will resolve in most children. About two-thirds will be able to drink milk by the time they go to school. In the remaining one-third, tolerance will continue to increase as they get older with only about one in 20 still allergic as adults.

Many infants and young children can introduce baked milk into their diet at home after allergy assessment. Many children can make progress with milk introduction at home under supervision of the dietitian using a milk ladder, increasing amounts of milk-containing foods in their diet. Some children/individuals may need to come to hospital for an oral food challenge to baked milk to see if they are outgrowing their milk allergy. This reintroduction, or putting dairy back into an individual’s diet, should not be attempted without the advice of your dietitian, doctor, or nurse.

What is the treatment?

The treatment for cow’s milk allergy is to avoid milk until the allergy resolves. As cow’s milk is an excellent source of protein and calcium, dietary review is important to ensure an individual’s nutrition needs are met. An infant with milk allergy may require a hypoallergenic formula milk to replace a standard infant formula. The dietitian or doctor can advise on the most suitable product.

Which milk substitutes can I use?

There are many plant-based milk drinks available in the supermarkets, based on soya, oat, coconut, nuts, hemp or pea, that would be suitable for individuals with milk allergy. Try to choose one that is calcium-fortified and unsweetened.

Infants and children under two years of age should be given a suitable cow’s-milk-free formula to ensure adequate intakes of vitamins and calcium. Your doctor or dietitian can offer advice on the most suitable formula for your child.

In instances where a specialist formula is not indicated, or where a child is more than two years of age, other plant-based milk drinks can be used such as soya milk, oat milk, pea milk or nut milks. Rice milk is a suitable cow’s milk substitute only for children over the age of 4½ years. It is recommended that you choose a cow’s milk substitute which is calcium and vitamin enriched.

How to read a label for a milk-free diet

Cow’s milk is added to many manufactured foods. It is important therefore to read the food ingredient label carefully.

Pre-packed foods for sale within the UK containing milk are required by EU law to be highlighted in the ingredients list. This may be in bold, underlined or in italics. However please remember foods sold outside the EU do not have to comply with these laws. Labels that say ‘may contain …’ are not covered by labelling laws. They are used to indicate that the food is produced in the same area as foods containing allergens and there may be a risk of cross-contamination. It is very difficult to tell how much milk is in these foods. Please talk to your specialist or dietitian about the safest approach to these foods.

Under EU food labelling regulations there must also be a list of product ingredients available for all foods that may not be labelled as they are sold loose such as those sold in a delicatessen, bakery, butcher and self-service counters. This may be written down or explained verbally. Care must be taken obtaining food from these settings as there is a risk of cross-contamination.

Check ingredient labels every time when buying foods as products are often altered and ingredients may have changed. Lists of milk-free foods can be obtained directly from food manufacturers and supermarket chains. They can be very helpful in identifying which foods are safe to eat.

Allergen avoidance

Avoid foods with the following ingredients:

• Butter, butter fat, butter milk, butter oil
• Butter acid, butter esters
• Casein, caseinates, hydrolysed casein
• Calcium caseinate, sodium caseinate
• Cow’s milk (fresh, dried, evaporated, condensed, powdered, UHT)
• Cheese, cheese powder, cottage cheese
• Cream, artificial cream
• Curds
• Ghee
• Ice cream
• Lactalbumin, lactalbumin phosphate
• Lactoglobulin, lactoferrin margarine
• Milk solids (non-fat milk solids, milk sugar, milk protein, skimmed milk powder)
• Animal milks (goat’s milk)
• Sour cream, sour cream solids
• Sour milk solids
• Whey, hydrolysed whey, whey powder, whey
• syrup sweetener
• Yogurt, fromage frais

Please also see the table below entitled 'Cow’s milk protein allergy: Suitable and unsuitable foods'.

What about nutrition?

Dairy products are important sources of energy, protein, calcium, and vitamins. Whilst many of these nutrients can be obtained from other foods, cow’s milk is the main source of dietary calcium. When dairy is removed from an individual’s diet, it is important to ensure that there is enough calcium from other foods. If a calcium and/or vitamin supplement is required, a dietitian can advise on an appropriate product and dose.

The Department of Health recommends that all children under the age of five take a supplement containing vitamin D (8.5 to 10mcg vitamin D for babies under one year; 10mcg vitamin D for children aged one to four years). Many suitable preparations are available over the counter at pharmacies and supermarkets.

However, if your child is taking more than 500ml of formula milk per day, then they will not require a vitamin D supplement as the formula milk provides enough vitamin D. A dietitian or local pharmacist can provide further information if required.

What is lactose intolerance?

Lactose intolerance occurs where an individual is not able to digest the lactose sugars in dairy products. These individuals have a deficiency in the gut enzyme lactase. As the lactose is not broken down and absorbed, it ferments in the gut and produces symptoms of bloating, excessive flatulence or wind and watery, explosive diarrhoea. Individuals with lactose intolerance can have some milk ingestion without symptoms, depending on the degree of lactase deficiency, the concentration of lactose in the cow’s milk product, and the amount of dairy ingested. They will also, unlike cow’s milk allergic individuals, naturally be able to drink lactose-free milks.

Are medications containing milk or lactose suitable for milk-allergic individuals?

Certain medications and dietary supplements where cow’s milk is used in their manufacture (such as probiotics) may contain traces of milk protein. These may be sufficient to elicit reactions in highly sensitive cow’s milk allergic individuals. Pharmaceutical grade lactose is widely used as an additive in a variety of medications including tablets, oral suspensions, intravenous formulations, and dry powder inhalers for asthma. This lactose is highly refined and therefore allergic reactions are very unlikely in most milk-allergic individuals. Clearly, where they do occur, lactose-free alternatives are recommended.

What about younger siblings of children with cow’s milk protein allergy?

Siblings of children diagnosed with cow’s milk protein allergy are more likely to develop cow’s milk allergy themselves. Breastfeeding has many benefits and is preferable for at least the first four to six months. If breastfeeding is not possible, please discuss with your allergy team about the best choice of formula.

Please note: All branded products are cow’s-milk-free at the time of printing; however, ingredients do change over time so please continue to check the labels.

This is also not an exhaustive list and products can change frequently so it is advisable to look in local supermarkets for additional suitable products. Detailed information on manufactured products can be obtained online or from the customer services department of most supermarkets.

Resources

• British Dietetic Association. Milk Allergy. (opens in a new tab)
• Muraro et al 2014. EAACI Food Allergy and Anaphylaxis Guidelines: Primary Prevention of Food Allergy. Allergy 69:590-601.
• Luyt et al 2014. BSACI milk allergy guidelines. Clin Exp Allergy 44(5): 642-672