When a baby is allergic to milk, it means that his or her immune system, which normally fights infections, overreacts to proteins in cow's milk. Every time the child 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 .
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 have a lower risk of having a milk allergy than formula-fed babies.
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.
If your baby has a milk allergy, keep two epinephrine auto-injectors on hand in case of a severe reaction (called anaphylaxis). An epinephrine auto-injector is an easy-to-use prescription medicine that comes in a container about the size of a large pen. Your doctor will show you how to use it.
What Are the Signs & Symptoms of a Milk Allergy?
In children who show symptoms shortly after they have milk, an allergic reaction can cause:
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
If you're not sure if your child has an intolerance versus an allergy, talk to your doctor.
If Your Child Has an Allergic Reaction
If your child has symptoms of an allergic reaction, follow the food allergy action plan your doctor gave you.
If your child has symptoms of a serious reaction (like swelling of the mouth or throat or difficulty breathing, or symptoms involving two different parts of the body, like hives with vomiting):
Give the epinephrine auto-injector right away. Every second counts in an allergic reaction.
Then, call 911 or 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.
How Is a Milk Allergy Diagnosed?
If you think your infant is allergic to milk, call your baby's doctor. He or she will ask you questions and talk to you about what's going on. After the doctor examines your baby, some stool tests and blood tests might be ordered. The doctor may refer you to an allergist (a doctor who specializes in treating allergies).
The allergist 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, epinephrine auto-injectors will be prescribed.
Avoiding a Milk Allergy Reaction
If You're Breastfeeding
If your breastfed infant has a milk allergy, talk to the allergist before changing your diet.
If You're Formula Feeding
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.
If you have any questions or concerns, talk with your child's doctor.
Reviewed by: Michelle Clark, MD and Hillary B. Gordon, MD