Babies often develop rashes, and finding a cause is often difficult. However, some rashes result from a cow milk allergy. A dairy allergy rash may be raised, discolored, and itchy. Rashes can appear suddenly or gradually. Additionally, they may worsen or improve over time.

A cow milk allergy is one of the most common food allergies globally. In the United States, 1.9% of children have a milk allergy.

Some babies show symptoms of a dairy allergy or intolerance before they begin eating solid foods. This is because breast milk and formula often contain cow milk proteins.

Milk proteins in a breastfeeding person’s diet can pass into breast milk and cause a reaction in sensitized babies. Most formulas contain cow’s milk, but dairy-free options are available.

Allergic reactions can vary from mild to severe. Symptoms in babies include a rash, wheezing, and swelling around the mouth.

This article looks at the symptoms of a dairy allergy in infants and discusses what else may cause a rash. It will also explain when to contact a doctor about a rash.

A dairy allergy is an overresponse by the body’s immune system to proteins in cow’s milk. There are many proteins in milk, but casein and whey are the most likely to be allergens.

There are two types of milk allergy:

  • IgE-mediated: The immune system reacts to milk proteins by creating immunoglobulin (IgE) antibodies. The immune system then releases chemicals, such as histamines, which trigger an allergic reaction. Symptoms of an IgE-mediated allergic reaction can appear within minutes of consuming dairy. This type of allergy can lead to anaphylaxis, which can be life threatening.
  • Non-IgE-mediated: Other parts of the immune system react to milk proteins and cause symptoms, often involving the digestive tract. Symptoms do not appear immediately. This type of reaction does not involve IgE antibodies.

Learn more about milk allergy in babies here.

An IgE-mediated milk allergy can be life threatening, so it is vital to know the symptoms. Symptoms of an IgE-mediated milk allergy appear within 5–30 minutes of ingesting milk and include:

SkinDigestiveBreathingBehavioral
Common symptoms• raised red bumps on the face or body that may be itchy

• flushed, red skin

• a sudden flare-up of existing eczema
• stomach pain

hiccups

• vomiting

• diarrhea
• coughing
• arching the back and bringing the knees to the chest

• rubbing the eyes, which may be itchy or red

Severe symptoms• swelling of the lips, tongue, and throat• vomiting

• diarrhea
wheezing

• shortness of breath

• difficulty swallowing

• hoarse cry, due to swelling of the throat
• floppy, limp, pale, or unable to wake easily

If a baby has an IgE-mediated milk allergy, a pediatrician may prescribe an epinephrine auto-injector (EpiPen). Caregivers will receive training on how to use it in an emergency. If a baby displays the severe symptoms above, a caregiver should administer epinephrine and then call 911.

Symptoms of a non-IgE-mediated milk allergy may take hours or days to appear and include:

SkinDigestiveBreathingBehavioral
• itchy skin

• flushed, discolored skin

• rashes that come and go

• eczema
colic, which is frequent, unexplained crying where the baby seems unsettled and uncomfortable

• bloating and gas

• reflux, where the baby vomits mouthfuls of milk

blood in the stool

• loose, watery stools

• upset stomach

vomiting or diarrhea 2–24 hours after having milk
• babies rarely experience breathing difficulties due to a non-IgE-mediated allergy• reluctance or refusal to feed

• slow to grow or gain weight

Learn about baby poop and milk allergy here.

Could it be lactose intolerance?

A milk allergy is more common than lactose intolerance in children under 5 years old. Very few babies have lactose intolerance, which usually develops later in life.

Babies develop lactose intolerance when they are born without the enzyme necessary to digest lactose, a sugar in milk.

If a baby develops symptoms after consuming cow’s milk, they are more likely to have a milk allergy than lactose intolerance.

Learn more about lactose intolerance here.

Skin rashes are common in babies and can have many causes, including:

The American Academy of Dermatology Association notes that some children with COVID-19 develop multisystem inflammatory syndrome in children (MIS-C). This condition can cause a rash. The symptoms include:

  • fever
  • abdominal pain
  • vomiting
  • diarrhea
  • rash
  • bloodshot eyes

If a child develops these symptoms, caregivers should contact a doctor immediately.

In many cases, a rash does not have a serious cause. If caregivers are concerned about a rash and other symptoms, they can talk with a doctor.

Most rashes will disappear on their own and do not require any special treatment. A baby’s skin is very delicate, so caregivers should avoid applying medication unless a doctor prescribes it for the baby.

Tips for looking after a baby’s skin include:

  • Avoid rubbing and scrubbing the baby’s delicate skin.
  • Use a soft washcloth to gently wipe away any milk, formula, or spit-up to avoid it sitting on the skin.
  • Keep skin cleaning to a minimum to avoid stripping the skin of its natural oils.
  • Use fragrance-free, hypoallergenic products.
  • Avoid products containing perfumes or dyes.
  • Use water that is lukewarm, not hot.
  • Use physical barriers, such as clothing, hats, umbrellas, and shade, to protect a baby’s skin from the sun.

Find 27 natural and organic baby products here.

If a baby has symptoms of a dairy allergy, their caregiver should make a doctor’s appointment as soon as possible. The doctor may refer them to an allergist for testing and diagnosis.

If the child displays the following symptoms, call 911 for emergency medical help:

  • shortness of breath
  • a tight or swollen face
  • a purple or discolored rash that looks like a bruise

The box below explains what to do in the event of anaphylaxis.

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

  • hives
  • swelling of the face or mouth
  • wheezing
  • fast, shallow breathing
  • a fast heart rate
  • clammy skin
  • anxiety or confusion
  • dizziness
  • vomiting
  • blue or white lips
  • fainting or loss of consciousness

If someone has these symptoms:

  1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
  2. Dial 911 or the number of the nearest emergency department.
  3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
  4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

According to the American College of Allergy, Asthma, and Immunology, 2–3% of children under 3 have a milk allergy. Around 20% of children outgrow their allergy by the age of 3.

About 80% of children outgrow their milk allergy before they are 16.

The only way to avoid allergic reactions in babies with a cow milk allergy is to avoid giving them cow’s milk or food containing it, including certain infant formulas. People who breastfeed should also avoid consuming milk products, as milk proteins can pass into breast milk.

Rashes are common in babies and young children, and they have many causes. Milk allergies are also common and cause symptoms ranging from mild to severe.

Rapid allergic reactions to milk may cause skin symptoms, such as itchy, raised, and red or discolored bumps.

A baby may also experience swelling around the mouth, difficulty breathing, and agitation. If a baby experiences these symptoms, caregivers should call 911 immediately.

Delayed allergic reactions may cause skin symptoms, such as eczema, rashes that come and go, and skin flushing. This type of reaction may also cause digestive symptoms, such as gas, diarrhea, or bloody stool. Caregivers should make a doctor’s appointment. The doctor may advise allergy testing.

Many other conditions can cause a skin rash. In many cases, a rash will clear without treatment.

Caregivers should care for a baby’s delicate skin by using mild, hypoallergenic products, lukewarm water, and avoiding rubbing.