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What is cow's milk allergy?

Cow’s milk allergy is a type of food allergy. It happens when the body’s immune system wrongly identifies proteins in cow’s milk as a threat.

In the UK, cow’s milk allergy affects two to three out of 100 babies. It usually starts in babies under 12 months of age and most outgrow their allergy during childhood.

Cow’s milk allergy is uncommon in adults. Older children and adults who are allergic to cow’s milk tend to have a more serious allergy.

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What are the types of cow’s milk allergy?

There are two main types of cow’s milk allergy: immediate and delayed. With both types, there is often, but not always, a close family history of allergy – where a parent or sibling has a food allergy or a related condition such as eczema, hay fever or asthma.

Immediate cow’s milk allergy

Immediate cow’s milk allergy is also called ‘IgE mediated’ cow’s milk allergy as it involves IgE antibodies, which are part of the immune system. Reactions usually come on very fast, between minutes and up to two hours after drinking cow’s milk or eating foods that contain dairy.

 

Symptoms can vary, but in some people this type of allergy can cause anaphylaxis, a serious, life-threatening reaction.

Delayed cow’s milk allergy

Delayed cow’s milk allergy is also called ‘non-IgE mediated’ as it involves a different part of the immune system and does not involve IgE antibodies. Symptoms can vary but mainly affect the digestive system and skin. Symptoms usually start between four and 48 hours after drinking cow’s milk or eating foods containing dairy.

 

There are other types of delayed allergic conditions that can be triggered by milk such as Food Protein-Induced Enterocolitis Syndrome (FPIES) and Eosinophilic Esophagitis (EoE). There are also non-allergic conditions that do not involve the immune system, such as lactose intolerance. These conditions are not covered here.

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What are the symptoms of immediate cow’s milk allergy?

Mild to moderate symptoms: 

  • a red raised itchy rash (known as hives or urticaria) anywhere on the body  
  • swelling of the face, lips and/or eyes  
  • a tingling or itchy feeling in the mouth 
  • mild throat tightness 
  • stomach pain, vomiting or diarrhoea. 

More serious symptoms of immediate cow's milk allergy

The term for this more serious reaction is “anaphylaxis” (pronounced ana-fil-ax-is).

Healthcare professionals consider an allergic reaction to be anaphylaxis when it involves difficulty breathing or affects the heart rhythm or blood pressure. Any one or more of the ABC symptoms above may be present.

In extreme cases there could be a dramatic fall in blood pressure. The person may become weak and floppy and may have a sense of something terrible happening. Any of the ABC symptoms may lead to collapse and unconsciousness and, on rare occasions, can be fatal.

More serious symptoms are often referred to as the 'ABC' symptoms and can include:
  • right_arrow_orange_icon AIRWAY - swelling in the throat, tongue or upper airways, hoarse voice, difficulty swallowing
  • right_arrow_orange_icon BREATHING - sudden onset wheezing, breathing difficulty, noisy breathing, persistent cough
  • right_arrow_orange_icon CIRCULATION - dizziness, feeling faint, sudden sleepiness, confusion, pale clammy skin, loss of consciousness or collapse
Read more about anaphylaxis
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What are the symptoms of delayed cow’s milk allergy?

Symptoms can include:

• Stomach pains
• diarrhoea (which might be bloody)
• constipation
• being sick
• itchy skin
• rash
• eczema.

Diagnosing immediate cow's milk allergy

If you think you or your child may be allergic to cow’s milk, see your GP. If symptoms are mild, your GP may manage this allergy in primary care. The GP can refer you to the general peadiatric or allergy clinic if needed, or if a supervised food challenge is needed. They can find a clinic in your area from British Society for Allergy and Clinical Immunology
(BSACI).

Read more about allergy testing

What can mean you're at higher risk?

Some clues that you might be at higher risk of more serious reactions are:

  • you have already had a serious reaction, with any of the ‘ABC’ symptoms
  • you have asthma, especially if it is not well controlled
  • you have reacted to a tiny amount of milk or dairy.

If you or your child have asthma, and it is not well controlled, this could make an allergic reaction worse. Make sure you discuss this with your GP or allergy specialist and take any prescribed medicines.

Diagnosing delayed cow’s milk allergy

Delayed cow’s milk allergy can be more difficult to diagnose as there are no specific diagnostic tests for delayed allergies. In a Delphi consensus study, it was agreed that differential diagnoses needed to be considered for faltering growth, bile-stained vomiting, blood in the stool, colic and crying.

A milk free diet can be trialled for a period of 2-4 weeks followed by re-introduction of milk into the diet whilst monitoring symptoms to confirm or exclude suspected milk allergy.

Treating symptoms

If you have mild allergic symptoms, you may be prescribed antihistamine medicine that you take by mouth. But if you are at risk of a serious allergic reaction (anaphylaxis), you may be prescribed adrenaline – the emergency medicine used to treat anaphylaxis. It is also known as epinephrine. 

Because anaphylaxis can happen very quickly, adrenaline is available in different forms that are designed to be easy to use. It’s important to know exactly how and when to use your prescribed adrenaline.  Healthcare professionals can show you how to use it, and there are also resources such as practice devices and videos on manufacturer websites. 

Options currently available on prescription in the UK include: 

  • Adrenaline auto-injectors (AAIs) – EpiPen and Jext. 
  • Intranasal adrenaline – EURneffy, a needle-free nasal spray. 

You must carry two in-date forms of prescribed adrenaline at all times as a second dose may be needed if symptoms do not improve after five minutes or get worse.  

Find out more about adrenaline. 

Read more about what to do in an emergency

Seeing a dietitian

Cow’s milk provides important nutrients such as protein, energy, fat, vitamins, and minerals (including calcium and iodine). If you or your child has a cow’s milk allergy, your GP or allergy clinic can refer you to a dietitian for personalised advice.

A dietitian can help determine whether cow’s milk needs to be completely avoided or whether certain forms of milk or dairy can be safely tolerated. Tolerance can depend on several factors, including the amount consumed, how frequently it is eaten, and whether the milk is cooked—and if so, for how long and at what temperature.

They will also support you in achieving a balanced and nutritious diet while avoiding milk and dairy where necessary.

Avoiding cow's milk

Once you have been diagnosed with a cow’s milk allergy, you will need to avoid it and foods that contain cow’s milk or cow’s milk protein.

Read the ingredient lists on food packets carefully every time you shop. Cow’s milk is included in the list of top 14 major food allergens in the UK. This means it must be highlighted on ingredients labels, in bold for example.

Read the ingredient list every time you buy a product as manufacturers change their recipes often.

When eating out

Restaurants, cafes, hotels, takeaways and other catering businesses are required by law to provide information on major allergens including cow’s milk. Ask staff directly if the food you’d like to buy contains cow’s milk and if there is a risk of cross contamination. Let them know that even small quantities can cause a reaction and don’t be afraid to ask staff to check with the chef.

The following foods and ingredients can contain cow’s milk protein:
  • right_arrow_orange_icon butter, buttermilk, butter oil, ghee and margarine
  • right_arrow_orange_icon casein (curds), caseinates, hydrolysed casein, calcium caseinate, sodium caseinate
  • right_arrow_orange_icon cheese, cheese powder and cottage cheese
  • right_arrow_orange_icon cow’s milk, including fresh, condensed, dried, evaporated and powdered milk, such as infant formulas
  • right_arrow_orange_icon cream, sour cream, crème fraiche and ice cream
  • right_arrow_orange_icon lactalbumin and lactoglobulin
  • right_arrow_orange_icon whey, hydrolysed whey, whey powder, whey syrup sweetener
  • right_arrow_orange_icon yogurt and fromage frais
Read more about shopping and preparing food

Reintroducing cow’s milk

Your allergy specialist or dietitian will talk to you about whether it’s possible to start reintroducing milk into your child’s diet as they get older. Download our cow’s milk allergy factsheet to find out more.

Airborne and contact reactions

Serious allergic reactions usually only happen after eating or drinking something containing milk protein, but reactions can happen after touching or breathing it in. A splash of milk on the skin can cause a skin reaction such as a rash or hives. If milk gets into a cut in the skin, onto the lips or in the eyes, the reaction could be more serious. Cow’s milk protein can become airborne when milk is heated (e.g. frothing in coffee shops), potentially causing mild symptoms like eye/nose itchiness or airway irritation if you are very sensitive. Serious reactions are uncommon from airborne exposure; symptoms are more often limited to eyes/nose/airways. Well-controlled asthma lowers the risk of serious reactions.

Always ensure asthma is well controlled, discuss with your GP or allergy specialist, as this reduces the risk of serious reactions from any allergen exposure, including indirect
contact.

How do I feed my baby if they have a cow’s milk allergy?

  • Breastfeeding

    Cow’s milk allergy usually happens when formula milk is introduced to a baby’s diet or when introducing solid foods. It is very uncommon in babies who are solely breastfed.

    If you have been advised to cut milk out of your diet and you are breastfeeding this
    should be for a time limited trial of 2-4 weeks. You should also be prescribed a calcium and vitamin D supplement. Do not cut foods out of your diet without guidance from a healthcare professional.

    Dietary exclusion when breastfeeding can have a detrimental effect (nutrition, quality of life) on the mother and potentially affect breastfeeding without appropriate healthcare professional support.

  • Hypoallergenic formulas

    If your baby is not breastfeeding, your doctor can prescribe a type of hypoallergenic infant formula called ‘extensively hydrolysed formula’. These are suitable for babies with cow’s milk allergy as they contain fully broken-down proteins that the body doesn’t react. If an extensively hydrolysed formula (EHF) isn’t tolerated, your clinician may consider a hydrolysed rice protein formula (HRF) (available on NHS prescription) or an amino-acid formula. Your healthcare professional will be able to advise you on the correct formula for your baby.

  • The ‘Comfort’ range of formulas

    The ‘Comfort’ range of formulas are not suitable as the milk proteins are only partially broken down, so could still cause a reaction.

     

  • Lactose-free milk

    Lactose is a sugar naturally found in cow’s milk. Lactose-free milk is not suitable as it still contains the milk proteins which cause allergic reactions.

  • Soya-based formulas

    These are no longer available in the UK. Soya milk can be added to foods after the age of 6 months as part of complementary feeding.

    There can be co-existing allergy between cow’s milk and soya, more commonly seen with a delayed milk allergy, but for most babies with a milk allergy soya will not cause any issues at all. If you are concerned, speak with a healthcare professional who can advise when and how soya can be introduced.

  • Rice milk and other milk substitutes

    Rice milk (not to be confused with a hydrolysed rice formula) is not recommended for
    children under four and a half years of age.

    Fortified plant-based milk alternatives—such as soya, oat, pea, coconut and nut milks—can be used from six months to mix with foods or added to cereal but should not be given as a main drink until a child is at least twelve months old. From twelve months of age, ready made plant-based milks can be used as a main drink, if the child is growing well and has a varied diet. It is important to choose a fortified product with added calcium; not all organic milks are fortified. If your child is unable to accept any suitable milk alternatives, seek advice from a dietitian, as vitamin or mineral supplements may be needed.

  • Milk from other mammals

    Milk from animals such as goat and sheep all have similar proteins so are not recommended.

Do babies outgrow cow's milk allergy?

Most babies outgrow their cow’s milk allergy during childhood, with the majority becoming tolerant by around four years of age. Delayed (non-IgE-mediated) cow’s milk allergy is often outgrown more quickly than immediate (IgE-mediated) allergy, sometimes within the first few years of life. While most cases begin in infancy, it is possible—though uncommon—for cow’s milk allergy to first appear in adulthood.

Oral Immunotherapy for cow’s milk allergy

Milk OIT is available in some NHS specialist centers (and privately) but access is limited and suitability is assessed case-by-case. OIT aims to raise the reaction threshold, not cure the allergy; ongoing dosing and safety rules are essential.

OIT must always be carried out under the supervision of an allergy specialist. The aim of milk OIT is to build up tolerance to a defined amount of milk so there is less risk of a serious allergic reaction if milk is accidentally consumed. It is not a cure for milk allergy and there is a risk of reacting to the milk dose. There are rules when taking the dose which must be strictly followed. Not all children with more persistent milk allergy will be suitable for milk OIT; studies show that those who react to very small amounts of milk may have lower success rates and a higher likelihood of side effects. Careful consideration by the immunotherapy team, and discussion between the team and patient/caregivers, is required to assess the suitability of treatment.

Read more about food immunotherapy

Key Messages

  • right_arrow_orange_icon If you or your child have allergy symptoms after drinking cow’s milk or eating foods containing dairy, visit your GP.
  • right_arrow_orange_icon Cow’s milk allergy is usually outgrown during childhood.
  • right_arrow_orange_icon Your GP or allergy specialist, with support from a dietitian, can advise you on which foods to avoid and how to eat a balanced diet.
  • right_arrow_orange_icon If you are prescribed adrenaline, carry two in date doses with you at all times.

Download our cow’s milk allergy factsheet

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