Health Library

What Is a Milk Allergy?

When a baby is allergic to milk, it means that their immune system, which normally fights infections, overreacts to proteins in cow’s milk. Every time the baby has milk, the body thinks these proteins are harmful invaders and works hard to fight them. This causes an allergic reaction in which the body releases chemicals like

histamine
.

Cow’s milk is in most baby formulas. Babies with a milk allergy often show their first symptoms days to weeks after they first get cow milk-based formula. Breastfed infants can show symptoms when their mother has had milk products.

People of any age can have a milk allergy, but it’s more common in young children. Many kids outgrow it, but some don’t.

What Are the Signs & Symptoms of a Milk Allergy?

In children who show symptoms shortly after they have milk, an allergic reaction can cause:

• wheezing
• trouble breathing
• coughing
• hoarseness
• throat tightness
• stomach upset
• vomiting
• diarrhea
• itchy, watery, or swollen eyes
• hives
• swelling
• a drop in blood pressure causing lightheadedness or loss of consciousness

The severity of allergic reactions to milk can vary. The same child can react differently with each exposure. This means that even though one reaction was mild, the next could be more severe and even life-threatening.

Children also can have:

• an intolerance to milk in which symptoms — such as loose stools, blood in the stool, refusal to eat, or irritability or colic — appear hours to days later
• lactose intolerance, which is when the body has trouble digesting milk

If you’re not sure if your child has an intolerance versus an allergy, talk to your doctor.

How Is a Milk Allergy Diagnosed?

If you think your infant is allergic to milk, call your baby’s doctor. The doctor will examine your baby, and might order some stool tests and blood tests. The doctor may refer you to an allergist, who might do skin testing. In skin testing, the doctor or nurse will place a tiny bit of milk protein on the skin, then make a small scratch on the skin. If your child reacts to the allergen, the skin will swell a little in that area like an insect bite.

If the allergist finds that your baby is at risk for a serious allergic reaction, they’ll prescribe epinephrine auto-injectors.

How Is an Allergic Reaction Treated?

If your baby has a milk allergy (or any kind of serious food allergy), always have two epinephrine auto-injectors available in case of a severe reaction. 

An epinephrine auto-injector is a prescription medicine that comes in a small, easy-to-carry container. It’s easy to use. Your doctor will show you how. Kids who are old enough can be taught how to give themselves the injection. If they carry the epinephrine, it should be nearby, not left in a locker or in the nurse’s office.

The doctor can also give you an allergy action plan, which helps you prepare for, recognize, and treat an allergic reaction. Share it with anyone who takes care of your child, including relatives, daycare providers, and babysitters. 

Every second counts in an allergic reaction. If your child starts having serious allergic symptoms, like trouble breathing, give the epinephrine auto-injector right away. Also give it right away if the symptoms involve two different parts of the body, like hives with vomiting. Then call 911 and take your child to the emergency room. Your child needs to be under medical supervision because even if the worst seems to have passed, a second wave of serious symptoms can happen.

Sometimes allergists recommend also carrying over-the-counter (OTC)

antihistamines
, as these can help treat mild allergy symptoms. Use an antihistamine after — not as a replacement for — the epinephrine shot during a life-threatening reaction.

What Can I Do if My Baby Has a Milk Allergy?

If You Breastfeed

If your breastfed infant has a milk allergy, talk to the allergist to see what changes you should make to your diet.

If You Formula Feed

If you’re formula feeding, your doctor may advise you to switch to an extensively hydrolyzed formula or an amino acid-based formula in which the proteins are broken down into particles so that the formula is less likely to trigger an allergic reaction.

You also might see "partially hydrolyzed" formulas, but these aren’t truly hypoallergenic and can lead to a significant allergic reaction.

If you’re concerned about a milk allergy, it’s always best to talk with your child’s doctor and work together to choose a formula that’s safe for your baby.

Do not try to make your own formula. Commercial formulas are approved by the U.S. Food and Drug Administration (FDA) and created through a very specialized process that cannot be duplicated at home. Other types of milk that might be safe for an older child with a milk allergy are not safe for infants.

When your child is ready for solids foods, the best way to be sure a food is milk-free is to read the food label. Manufacturers of foods sold in the United States must state on their labels whether the foods contain milk. Check the ingredients list first.

Some foods look OK from the ingredient list, but while being made they can have contact with milk. This is called cross-contamination. Look for advisory statements such as "May contain milk," "Processed in a facility that also processes milk," or "Manufactured on equipment also used for milk." Not all companies label for cross-contamination, so if in doubt, call or email the company to be sure.

If you have any questions or concerns, talk with your child’s doctor.

For more about managing food allergies, visit:

• Food Allergy Research and Education Network (FARE).