Milk allergies in babies

A cows’ milk allergy in babies is also known as a cow’s milk protein allergy. It typically develops when cow’s milk is first introduced into your baby or child’s diet, either when formula feeding, or when your baby starts eating other dairy and milk products when they start weaning.

More rarely, babies who are exclusively breastfed can also develop a cow’s milk allergy. This is because, if you’re breastfeeding, it’s possible for the cow’s milk you consume in your diet to pass to your baby through your breast milk​².

It’s common for babies who are allergic to cows’ milk to be allergic to goats’ and sheep’s milk, too, as they contain similar proteins.

If you think your baby could have a cows’ milk allergy, it’s important to talk to your doctor to establish whether or not this is the case. If your baby is diagnosed with a cow’s milk protein allergy, you may be referred to a dietician to discuss how to manage the condition as your baby grows​².

There are two main types of cow’s milk allergy in babies²:

• Immediate cow’s milk allergy. The type of milk allergy is characterised by symptoms that occur immediately, usually within minutes, of your baby consuming cow’s milk. 
• Delayed cow’s milk allergy. Here, the symptoms tend to be delayed by several hours, or in some instances, days, from when  your baby consumes cow’s milk.  

A cow’s milk allergy in babies is likely to present any number of symptoms. These include²:

• A red itchy rash (cow’s milk allergies and rashes on babies are very common).
• Swelling of the lips, face and around the eyes.
• Tummy ache.
• Vomiting.
• Colic.
• Diarrhoea or constipation.
• Hay fever-like symptoms ( such as a runny, blocked nose).
• Eczema.

You should consult your health visitor or doctor if you find that your baby is affected in two separate areas of the body – for example, the stomach (vomiting) and skin (hives), and if they have more than one of the symptoms listed above¹.

Very rarely, a cow’s milk protein allergy can cause anaphylaxis, which is a severe allergic reaction. You must call for ambulance immediately if you suspect your baby has anaphylaxis or displays any of the following symptoms³:

• Swollen lips, throat, tongue and/or mouth.
• Struggling or unable to breathe - fast breathing, choking, gasping or wheezing.
• Skin or lips turning blue.
• Becoming limp or floppy, or not responding as they usually would.

Unfortunately, there’s no single diagnostic test for a cows’ milk allergy in adults, babies or young children. Usually, diagnosis involves having a combination of tests and a series of elimination and reintroduction diets in order to get to the bottom of things.

These tests usually happen once your baby has been referred to a specialist, who may be a dietician, by your doctor. Remember that it's very important to seek advice from your doctor if you suspect that your baby has an allergy so that they can be properly diagnosed and treated.

Our  Baby Symptom Checker is a great tool to use if your baby is less than a year old. While it doesn't replace the need for medical advice, it includes useful tips for you to use, and a symptom summary that you can show your pharmacist, health visitor or GP. 

Babies can either be allergic or intolerant to milk. Because some of the symptoms are similar, it can be difficult to diagnose. What’s more, the names of these conditions are often used interchangeably, and not always correctly - it can be very confusing!

A milk allergy involves an immune reaction to one or more of the proteins present in milk, with symptoms affecting the gut, circulation, skin and respiratory systems⁴.

A milk intolerance in babies is caused by an inability to deal with certain substances it contains, such as lactose. Lactose intolerance occurs when you don't produce any or enough of the enzyme lactase, which breaks down lactose. Undigested lactose causes uncomfortable symptoms like diarrhoea, bloating and wind​⁴.

Watch our video to understand the difference between a milk allergy and milk intolerance in babies, and how to recognise the symptoms.

Knowing how to recognise the difference can help get a quicker diagnosis, and lead to an effective dietary management programme. If you're breastfeeding, this will be done by looking at your own diet and making any necessary changes that might be advised by a dietician or other healthcare professional. If your baby is formula fed, there are specialised formula milks to help with the dietary management of cow’s milk allergy symptoms.

If your baby is less than a year old, our Baby Symptom Checker is a good place to start, and you’ll find lots more information below to help you better understand your baby's symptoms.

Approximately 7%² of babies under the age of one are thought to be affected by a cow’s milk allergy, and it’s one of the most common food allergies seen in children². By the age of five, most children will have grown out of their cows’ milk allergy⁵.

Providing your doctor with as much information as possible about your baby’s symptoms will help them to make a diagnosis. The more evidence and information you can provide, the better.

It’s a good idea to keep a diary of your baby’s symptoms, including when they occur and how long they last for, as this can help your doctor identify or rule out a cows’ milk allergy. For example, if your baby comes out in a rash after feeding, take a photo, and make a note of how long it took for the rash to appear and how long it lasts. In addition, take a note of any vomiting, diarrhoea, stomach cramps or difficulty breathing, and when these happen in relation to eating, drinking or other activities.

Look particularly for two symptoms in two separate areas of the body, such as vomiting and a skin irritation. If this happens, be sure to inform your doctor and let them know if there’s a history of allergies in your family.

When your baby is diagnosed with a cows’ milk allergy, it’s only natural to think about how this will affect them moving forward, particularly when it comes to your child’s diet. However, once you know the cause of your baby’s symptoms, you can take positive steps to keep them healthy. 

Your GP will discuss the options for treatment with you, and you may be referred to a dietician to look at the foods your baby is eating and to make any necessary adjustments to their diet². 

Managing a cow’s milk allergy in babies and children involves removing all cow’s milk from their diet.

When introducing solid foods to a baby with a cow’s milk protein allergy, you'll need to get familiar with reading food labels and the ingredients on them, as milk can be found in unlikely places where you least expect it.

Whilst this might seem overwhelming at first, keep in mind that food labelling laws are there to help you, and common allergens, like milk, must be declared on pre-packaged foods.

Breast milk is the best form of nourishment for your baby, even if they’ve been diagnosed with a cow’s milk allergy.

While cow’s milk protein can pass into breast milk from your diet, most babies with a cow’s milk allergy can tolerate it⁶. In rare cases, babies do react to the cows’ milk in their mothers’ milk. If this happens, your healthcare professional or doctor may advise you to avoid all dairy products to see if this makes a difference to your baby’s symptoms.

You should only eliminate dairy from your diet on the advice of a doctor or other healthcare professional, for example a dietician or allergy specialist. This is to ensure that you’re not missing out on other vital nutrients that you need.

When breastfeeding you need 1,250mg of calcium every day⁷. That’s 550mg more than you’d usually need. This is normally achieved by drinking low-fat milk and eating foods like cheese, yoghurt and other healthy milk products regularly. To meet this increased requirement, you’d need to include dairy foods up to five times per day.

Most people get the majority of their calcium from dairy products. So, if you’ve been advised to follow a dairy-free breastfeeding diet, it’s important to boost your calcium intake in other ways. For example, by eating plenty of other dairy and milk-free sources of calcium instead. These include⁶:

• Tinned sardines, with the bones.
• Calcium-fortified fruit juices.
• Milk-free oat, rice or nut drinks. Babies with a cow’s milk allergy can also react to soya milk, so this is best avoided⁸. 
• Green, leafy vegetables such as kale.
• Calcium-fortified bread.

Vitamin D can help your body to absorb calcium from the food you eat⁷. As such, it’s recommended that all adults and children who are over the age of one year take a 10mg vitamin D supplement every day⁹.

Speak to your healthcare professional about your calcium and vitamin D intake to ensure you’re getting what you need.

If your baby is formula feeding and has been diagnosed with a cow’s milk allergy, your doctor or dietitian will prescribe a special hypoallergenic formula. The type of special formula that your baby needs will depend on their age, growth, severity of symptoms and nutritional requirements.

It may be that your baby is prescribed with a special kind of extensively hydrolysed formula. Here, the proteins in the milk have been broken down into smaller pieces so your baby’s immune system is less likely to recognise it as an allergen.

Rest assured that this process doesn’t affect the nutritional value of the formula, and it will still provide the wide range of nutrients, including vitamins and minerals, that your baby needs.

It’s normal for your baby’s feeding patterns and habits to change when you switch to an extensively hydrolysed formula, and it may take your baby a couple of weeks to get used to their new milk. You may also notice that their stools may be different, becoming looser and greener in colour. In more severe cases of cow’s milk allergy, or where an extensively hydrolysed formula doesn’t resolve all your baby’s symptoms, they may be prescribed an amino acid formula.

Many milks aren’t suitable for babies with a cows’ milk allergy. Soya-based products, including soya infant formula, are not recommended for babies under six months old.  This is because they contain plant-based compounds with oestrogen-like properties known as phytoestrogens.  Research has shown that 30–50% of babies who react to cows’ milk-based formulas might also react to soy-based formulas⁵.

Another type of formula unsuitable for babies with a cows’ milk allergy, is partially hydrolysed formula. The proteins in this type of milk are only partially broken down and can still cause an allergic reaction​¹⁰.

If you’re concerned that your baby has a cows’ milk allergy and you want more information on diagnosis or the side effects of cows’ milk alternatives, it’s very important to consult your doctor or healthcare professional, and not self-prescribe with over-the-counter milk alternatives.  

As we’ve already stated, a cow’s milk allergy can be difficult to diagnose given the variety of symptoms and potential causes. In fact, whilst the actual incidence of cows’ milk allergy is only around 7​​% (2), it’s estimated that up to 15% of babies may show symptoms that suggest a cows’ milk allergy might be at play.

As such, it’s important that you don’t self-prescribe or make any significant changes to yours or your baby’s diet without the advice of a doctor or dietitian.