What are the symptoms?

"Nothing would console her, she was in agony"

Alice Williams, Holyhead

If your baby has cow’s milk allergy, you may notice symptoms of an allergic reaction after they consume cow’s milk, dairy products or anything that contains cow’s milk protein.

So is it cow's milk allergy? Find out more about the signs and symptoms to look out for, to get an idea of whether your baby might be allergic to cow’s milk protein.

Which foods contain cow's milk protein?

Signs and symptoms to look out for

There are two types of cow’s milk allergy that have slightly different symptoms: IgE-mediated and non-IgE-mediated allergies.

Good to know
In a survey of 1,649 mums,1 the 142 who had a child with diagnosed or suspected cow’s milk allergy said that colicky abdominal pain and eczema were the most common symptoms, each affecting 42% of babies. 

In an IgE-mediated allergy, symptoms occur within minutes to a few hours after eating or drinking anything that contains cow’s milk protein. In a non-IgE-mediated allergy, symptoms can appear after many hours or up to a few days later.

The exact symptoms with either type of allergy can vary from baby to baby, but could include the ones shown below. Click on each to find out more.


Skin reactions

This can include an itchy red rash, hives (raised, red and often itchy bumps that could stay in one area or spread through the body), and swelling of the lips, face and around the eyes. 


Colicky abdominal pain

Babies with colicky abdominal pain could get severe cramping or pain in their tummy area, and might arch their backs.



Babies could feel sick or might projectile vomit.



A breastfed baby’s stools are usually runny and bitty, while a formula-fed baby’s stools tend to be a little thicker. If your baby has diarrhoea, you’ll notice frequent, watery, foul-smelling and loose stools. You should contact your doctor or health visitor if your baby gets diarrhoea, as they could quickly become dehydrated.


Hay fever-like symptoms

This can include sneezing and an itchy, runny or blocked nose.


Breathing difficulties or wheezing

This can include coughing, chest tightness, wheezing and shortness of breath. 



Anaphylaxis (anaphylactic shock) is the most serious possible allergic reaction – it comes on quickly, affects the whole body, and is potentially life-threatening. Signs include breathing difficulties, becoming faint, skin irritation and swellings especially of the face. Fortunately, this type of allergic reaction is uncommon in infants.

If you suspect anaphylaxis, call 999 for an ambulance immediately stating “ANAPHYLAXIS”. If your baby’s unconscious, check for breathing and then put them in the recovery position. If your baby’s conscious, it might help to sit them up to make it easier to breathe. You can find out more about what to do in the case of anaphylaxis here – but if you see the signs of anaphylaxis you MUST dial 999 first.



Colic is the medical term used to describe excessive, frequent crying in babies who otherwise appear to be healthy and well. The crying is usually very intense, and the baby’s face might be red and flushed and they may clench their fists, draw up their knees or arch their back. This tends to follow a pattern of threes – crying for more than 3 hours a day (usually in the evening), for more than 3 days a week, and for more than 3 weeks.


Skin reactions/eczema

Eczema is a condition where the skin is red, itchy, dry and cracked. It often affects areas with skin folds, such as behind the knees, the inside of elbows, the side of the neck and around the eyes and ears.



Reflux is where the contents of the stomach come back up towards the mouth. It's sometimes called "possetting" or "spitting up". Almost all babies get this to some extent, but in severe cases, babies can regurgitate lots of liquid, vomit forcefully, choke or gag, arch away from the bottle or breast, seem irritable during or after feeds, or have trouble putting on weight.


Unusual stools

Babies with cow’s milk allergy may have loose or frequent stools, and there could also be blood and/or mucus in their stools. The blood could be due to bleeding around their bottom, or from their bowels, and it’s important to speak to your doctor to find out what’s causing this bleeding. 


Abdominal pain

Babies could get severe cramping or pain in their tummy area, and might arch their backs.



The stools of a constipated baby might look like little rabbit pellets or hard balls. Your little one might go several days without producing anything or the stools can be difficult to pass. You may also notice some blood. Don’t judge whether your baby is constipated by how frequently they have a bowel movement – sometimes, infants can be healthy and go several days without one. 


Failure to thrive

This is when babies don’t gain enough weight. They might be lethargic, have a poor appetite or show developmental delays.



Babies with cow’s milk allergy might have lots of wind, and their stomachs can look bloated or feel hard or tense. Other signs include pulling up the legs or locking them straight out, or fist clenching.



Emollients are moisturising treatments that you apply to the skin. They can come in different forms, including creams, ointments, bath oils and soap substitutes. They can either be prescribed or bought over the counter from a pharmacy.



A hypoallergenic formula for cow’s milk allergy doesn’t contain whole cow’s milk proteins, so it’s unlikely to trigger an allergic reaction.



Histamines are a type of chemical that plays a major role in an allergic reaction. They are released by the immune system and cause blood vessels to open up, leading to the typical symptoms seen in many allergies including hay fever and cow’s milk allergy.



Lactase is an enzyme in the gut that breaks down lactose so it can be absorbed in the gut.


Extensively hydrolysed formulas

The cow’s milk proteins in an extensively hydrolysed formula have been broken down into small pieces, so they’re unlikely to be recognised by the immune system. This means that they shouldn’t cause an allergic reaction in the majority of babies with cow’s milk allergy. In fact, extensively hydrolysed formulas that are recommended by healthcare professionals are well accepted by at least 90% of infants with cow’s milk allergy.


Amino acid-based formulas

Amino acid-based formulas don’t contain any protein chains at all – they only use the basic building blocks of protein – amino acids. If your doctor has diagnosed your baby with severe cow’s milk allergy or multiple allergies, or you’ve tried an extensively hydrolysed formula and still notice symptoms, your doctor may recommend an amino acid-based formula.



Antibodies identify potential threats to your body, such as bacteria and viruses. They then signal to your immune system to release chemicals to deal with the threat.


Breathing difficulty or wheezing

This can include coughing, chest tightness, wheezing and shortness of breath. 


What if my baby has these symptoms?

If you think that your baby might be showing signs and symptoms of cow’s milk allergy, make an appointment to see your doctor. While you’re waiting to see him or her, start keeping a diary of your baby’s symptoms using our symptoms diary to jot down the symptoms you notice, and whether they flare up during or after feeds or at certain times of day. It’s then a good idea to note down this information over 1–2 weeks. It’s also essential to indicate which foods your baby’s consuming – whether it’s breast milk, formula or solids. Then take this diary to your doctor to help you discuss your concerns together and help to reach a diagnosis.

Symptoms Diary

“Mothers know best – if you think there’s something wrong, get it checked and stay positive.”

Mum of a child with CMA1