- Rash (known as hives or urticaria)
- Swelling of the skin (known as angioedema) anywhere on the body (e.g. lips, face)
- Stomach pain, feeling sick and vomiting
- Change in behaviour
Cow’s milk allergy happens when the body’s immune system wrongly identifies proteins in cow’s milk to be a threat.
In the UK, cow’s milk allergy affects 2-3 out of 100 babies. Cow’s milk allergy usually starts in babies under 12 months of age, with most outgrowing 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 cow’s milk allergy.
There are two types of cow’s milk allergy: immediate and delayed. With both types of cow’s milk allergy, there is often (but not always) a close family history of allergy such as eczema, hay fever, asthma or food allergy in a mother, father, brother or sister.
Immediate cow’s milk allergy is also called ‘IgE mediated’ as it involves IgE antibodies, which are part of the immune system. Reactions are usually very fast and happen between minutes and up to 2 hours after drinking cow’s milk or eating dairy containing foods. Symptoms can vary, but in some people this type of allergy has the potential to cause a serious, life-threatening allergic reaction called anaphylaxis.
Delayed cow’s milk allergy is also called ‘non-IgE mediated’ as it involves a different part of the immune system, not involving IgE antibodies. Symptoms can vary, but mainly affect the digestive system and the skin. Symptoms usually occur between 4 - 48 hours after drinking cow’s milk or eating dairy containing foods.
The term for this more serious reaction is “anaphylaxis”. 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. This may lead to collapse and unconsciousness and on rare occasions can be fatal.
Most healthcare professionals consider an allergic reaction to be anaphylaxis when it involves the ABC symptoms. Read our anaphylaxis factsheet for further information. It is essential that someone having anaphylaxis is given adrenaline.
A rare type of delayed allergic reaction to food is called Food Protein Induced Enterocolitis Syndrome (FPIES). The condition is more common in babies and young children and cow’s milk protein is one of the most common causes. Symptoms of FPIES include diarrhoea and severe and repeated vomiting. FPIES can result in drastic fluid loss – this is a medical emergency and urgent hospital admission is required.
There are other types of delayed allergic conditions also triggered by milk. There are also non-allergic conditions triggered by milk, which do not involve the immune system, such as lactose intolerance. These conditions are not covered in this factsheet.
If you suspect you or your child is allergic to cow’s milk, you must see your GP. If you need to be referred to a specialist allergy clinic, your GP can locate one in your area by visiting the website of the British Society for Allergy and Clinical Immunology (BSACI).
Immediate cow’s milk allergy is confirmed by a healthcare professional:
In a minority of cases a ‘food challenge’ may also be needed to confirm the diagnosis.
Delayed cow’s milk allergy can be more difficult to diagnose as there are no allergy tests that can tell whether a delayed allergy is present. Symptoms can also be similar to common conditions in babies, such as colic.
This type of allergy is confirmed by:
All cow’s milk must be removed for between 2-4 weeks, which should be discussed with a healthcare professional. For someone with delayed cow’s milk allergy, the symptoms will improve when cow’s milk is taken out of the diet and will reappear when cow’s milk is introduced again.
For those with immediate cow’s milk allergy, mild allergic symptoms can be treated with antihistamines.
If there is a risk of anaphylaxis, adrenaline auto-injectors (AAIs) will be prescribed. Two AAIs should be available at all times and it is important to know how and when to use them. An AAI should be used as soon as anaphylaxis is suspected, and a second AAI can be used after 5 minutes if symptoms don’t improve or get worse.
After the first AAI is used, someone must dial 999 immediately. The emergency service operator must be told the person is suffering from anaphylaxis (pronounced ana-fill-axis). Click here to read our Adrenaline factsheet for further information.
Cow’s milk is a source of protein, energy, fat, vitamins and minerals (such as calcium and iodine). If you or your child have a cow’s milk allergy, your GP or allergy clinic can refer you to a dietitian. This is important as a dietitian can give advice about which foods to avoid and suggest dairy-free alternatives, so you can achieve a balanced diet. Your dietitian can also advise whether it is necessary to take a vitamin or mineral supplement.
If you are allergic to cow’s milk you need to read food labels carefully. When eating out in restaurants, takeaways and other catering establishments question staff directly about ingredients.
Cow’s milk may also be found in some cosmetics and personal care products – it is important to read labels carefully.
Your allergy specialist or dietitian will advise when it is appropriate to start reintroducing milk into the diet. For those with a delayed milk allergy, this will be done gradually, usually at home, following something called a ‘milk ladder’. Baked milk is less likely to cause allergic reactions than lightly heated or fresh milk, so it is likely the advice will be to start with very small quantities of baked milk within food products (such as cakes or biscuits). This should only be done under the advice of a healthcare professional.
With immediate cow’s milk allergy, it is likely that further skin prick or blood tests will be needed before the reintroduction of milk, and that reintroduction will be supervised in an allergy clinic.
It is important to talk to your GP or allergy specialist about these types of contact reactions and how to manage the risk of a serious allergic reaction.
Cow’s milk allergy typically occurs when formula milk is introduced to a baby’s diet or when weaning on to solid foods is started. Cow’s milk allergy happens less in exclusively breastfed babies compared to formula-fed or mixed fed babies.
If your breastfed baby has a cow’s milk allergy you should continue to breastfeed and seek advice from your GP or dietitian. If the baby has no allergy symptoms when only breastfeeding, then there is no need for the mum to cut cow’s milk out of her diet. If the baby does have symptoms while breastfeeding, the mum may be advised to cut cow’s milk out of her diet. In this case, the mum should be prescribed a calcium and vitamin D supplement.
If not breastfeeding, a type of hypoallergenic infant formula called ‘extensively hydrolysed formula’ can be prescribed. These formulas are suitable for babies with cow’s milk allergy as they contain fully broken-down proteins. In serious cases, an ‘amino-acid formula’ may be prescribed. These do not contain any cow’s milk proteins.
The ‘comfort’ range of formulas are not suitable as the proteins are only partially broken down.
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.
These are not suitable for babies less than six months old. After six months old, soya-based formula may be considered for some children, but it is important to seek the advice of your GP or dietitian.
Rice milk is not recommended before the age of four and a half years. Ready-made oat, coconut, almond, pea and other ‘milk’ substitutes may be used after two years of age, but it is important to seek the advice of your GP or dietitian.
Milk from mammals, such as goat and sheep, all share similar proteins so are not recommended.
Most cases of cow’s milk allergy are outgrown during childhood. After that, it can still be outgrown, but some children will stay allergic into adult life. It is possible but unusual for cow’s milk allergy to start in adulthood.
Delayed cow’s milk allergy will usually be outgrown more quickly than immediate cow’s milk allergy, commonly in the first few years of life.
There are ongoing studies in the development of immunotherapy (also known as desensitisation) treatments for cow’s milk allergy. Click here to read our Allergen Immunotherapy factsheet for further information.