Milk Allergy 101: Complete Guide To Symptoms, Food Lists, And More

by Cassie Shortsleeve
Originally Published: 
milk allergy, glass of milk
pong-photo9/ Getty

As a new mom, there are plenty of things to worry about. A biggie on that list? Whether or not your baby has a food allergy — specifically, a milk allergy, one of the most common food allergies out there. After all, whether you’re feeding baby formula (many kinds can have milk in them) or have just added in solid foods (including milk-based options), a baby can’t exactly speak up and tell you that something isn’t sitting just right. Adults can also face milk allergies since allergies can develop at any age.

In fact, about 32 million Americans have food allergies or about 10 percent of adults and a little over 7 percent of children, according to the Asthma and Allergy Foundation of America. Specifically, milk allergies make up a big chunk of that number. After all, milk is one of the eight major food allergens, along with eggs, peanuts, tree nuts, wheat, soy, fish, and crustacean shellfish.

As prevalent as it is, there are a lot of misconceptions out there about milk allergies. After all, there’s a difference between having a true allergy to milk and having, say, lactose intolerance — more on that later. In short, a true allergy is an “abnormal response of the immune system to the cow’s milk protein allergen,” explains Dr. Aikaterini Anagnostou, M.D., Ph.D., director of the Food Immunotherapy Program at Texas Children’s Hospital.

So, what do you really need to know about milk allergies? And what should you do if you or your child is suffering from one? Here’s a complete guide to what this kind of allergic response looks like, how to spot one, and what to do.

What causes a milk allergy?

Well, on a physiological level, a milk allergy is caused by a malfunction in the immune system. If you have a milk allergy and you consume milk, your immune system IDs the proteins in milk as harmful. This triggers the body to create antibodies to attack the proteins — an effort to keep them from hurting you. The next time your body comes into contact with those milk proteins? Your body releases chemicals like histamine, which can cause a whole host of those symptoms that you’d recognize as an allergic reaction.

There are also some risk factors that can increase the chances that you’ll develop a milk allergy, including:

  • having other allergies (although a milk allergy might crop up before other allergies)
  • atopic dermatitis (a chronic inflammatory skin disorder)
  • a family history of milk allergy or allergic diseases such as asthma
  • Age (most infants who develop an allergy to milk develop it before age one, according to Food Allergy Research & Education)

The AAP, as well as research on the topic, suggests that dairy-free breastfeeding could prevent or delay the development of a milk allergy.

“A milk allergy is one of the most common food allergies in infants,” confirms Stephanie Middleberg, R.D., author of The Big Book of Organic Baby Food. By some estimates, about 2.5 percent of kids under three are allergic to milk. But, there’s good news. There’s plenty of milk alternatives for infants that your pediatrician can recommend.

Milk Allergy Symptoms

First, Anagnostou explains that there are two types of milk allergy: the immediate type and the delayed-type. These two types of milk allergies are called IgE-mediated and non-IgE-mediated allergies.

The difference? If you have an IgE-mediated milk allergy, your immune system overreacts and produces a bunch of antibodies called Immunoglobulin E (IgE) quickly. Non-IgE mediated food allergy reactions involve other parts of the immune system and don’t show symptoms as quickly.

Symptoms of IgE-mediated milk allergies occur within two hours of ingesting milk and may include:

  • hives
  • swelling of the lips or face
  • abdominal pain
  • vomiting
  • wheezing

With non-IgE mediated milk allergies, symptoms occur up to 72 hours after taking in milk, she says. They may include:

  • eczema
  • colic
  • reflux
  • constipation
  • diarrhea

Milk allergy symptoms can also, of course, differ from person to person. “Eczema and congestion are also signs of a potential milk allergy,” explains Middleberg. “Some parents may also see blood in their child’s stool although that is rarer.”

It’s important to remember that a milk allergy can also be very serious, causing anaphylaxis, a life-threatening reaction, The Mayo Clinic reports. If you notice any wheezing, shortness of breath, lip swelling, or if your child is becoming extremely pale or weak, call 9-1-1 immediately. Those are signs of a medical emergency.

Foods to Avoid if You Have a Milk Allergy

If someone is diagnosed with an allergy, the No. 1 basic guideline is fairly simple: avoid milk. But that can be easier said than done — and recommendations for what that means vary depending on the age of the patient.

For infants, a pediatrician might recommend they follow a milk-free diet if the baby has a milk allergy, according to the AAP. This would cut your child’s exposure to cow’s milk through your own milk. If your baby is formula-fed and has a milk allergy? You’ll want to give them another formula, such as soy or an elemental option, per your pediatrician’s guidelines, the AAP suggests. You can ask your pediatrician to recommend a hypoallergenic formula.

If you or your child have a milk allergy, you should avoid all milk products including:

  • milk
  • yogurt
  • kefir
  • cheese
  • butter
  • cottage cheese
  • ice cream
  • foods that include ingredients such as casein (a milk protein), whey, and butter

It’s also hugely important to look at labels closely (and learn to read them correctly!) since milk can sneak into foods like bread or cereals, Middleberg says. “Since it is a top allergen, companies have to list it as an ingredient on the food label.”

Is there a milk allergy test?

Yes — there are multiple tests and you should always see a doctor or allergist if you suspect one or if your child experiences any symptoms after consuming milk.

If you think something is slightly off — inconsistent poops or irregular formed poops; bloating, pain or fussiness; blood in stool; skin rashes; colic — you could start with a conversation with your pediatrician, says Middleberg. “From my experience as a mom with a child with food allergies, it is never a bad idea to have a conversation if you are the slightest bit concerned.”

An allergist can also confirm or rule out a milk allergy, explains Anagnostou, who notes that there are skin tests, blood tests, and other tests that can confirm results quickly.

At an appointment, an allergist will take a detailed medical history, asking what foods your child ate and what symptoms they experienced. They’ll then test for the allergy. The most common allergy tests (skin pricks and blood tests) look for those IgE antibodies that show up when you’re exposed to something that you’re allergic to.

In a skin-prick test, for example, a little bit of milk or milk protein extract would be placed on an area on your child’s arm or back to see if a rash or any signs of irritation show up. Blood tests would look for IgE antibodies. Your allergist could also order an oral food challenge where, under medical supervision, you’d test for an allergy by having your child consume a very small amount of a substance (or having the substance put on their lip). This type of test is common for many allergies.

Milk Allergy Rash

Curious about whether or not you have a milk allergy rash? A rash from cow’s milk may be scary to find on you or your child, but it’s can be a clear indication that something’s wrong. First and foremost, you’ll need to visit a doctor or pediatrician. They’ll likely review you or your child’s diet and think of great substitutes.

A rash should be expected to stay on your baby in two to four weeks after changing food or formula.

Casein Allergy

You might have heard about casein allergies before. That’s because casein is a popular milk protein, and allergies towards dairy or milk are often caused by a sensitivity to casein.

A casein allergy is something you need to take just as seriously. One of the worst symptoms of a casein allergy is anaphylaxis, which may lead to death. As a general rule, it’s always important to take allergies seriously. Not doing so could lead to irreversible consequences. Signs of anaphylaxis after being exposed to casein include mouth swelling, chest pains, difficulty breathing, and hives. These reactions indicate a serious reaction, and you should seek medical attention immediately.

Casein isn’t only found in milk. Here are some other products to avoid with a casein allergy:

  • cheese
  • pudding
  • yogurt
  • Butter
  • butter flavoring
  • margarine
  • nondairy creamers
  • whey

Sad to say, even some canned tunas and sausages include casein. You’ll want to read every label if you’re noticing any reactions.

Sudden Milk Allergy in Adults

Can adults have a sudden milk allergy out of nowhere? Unfortunately, the answer is yes. It’s not as common as it is with kids, but it does happen since our bodies are constantly changing. You might want to take a look at your family history to see if anyone else developed a sensitivity or allergy later in life. Many times, these things can be genetic.

What is the treatment for a milk allergy?

While your doctor or pediatrician could also suggest specific medications including antihistamines or anti-asthma medications (if wheezing is a milk allergy symptom), the main treatment for an allergy is simply to avoid it.

“Currently, dairy avoidance is recommended. But, there are novel research treatments in the pipeline such as milk oral immunotherapy,” says Anagnostou. Oral immunotherapy consists of giving someone who’s allergic to milk small amounts of it in a safe clinical setting with the goal of hopefully raising the threshold for the allergen over time.

It’s also, of course, incredibly important to make sure that all of the people who watch your child are aware of the allergy and that, when eating out, you alert staff to the allergy. If your child is at risk of a serious allergic reaction, talk to your doctor about emergency medications such as epinephrine, too. Having a child wear a medical alert bracelet or necklace is another option.

The good news: “There are a lot of dairy-free alternatives out on the market, from milk to yogurts to cheeses, and they are only getting better tasting and more natural,” says Middleberg.

Can a baby outgrow a milk allergy?

Absolutely — and it’s common. “The majority of children will outgrow their milk allergy during childhood,” says Anagnostou.

Of course, it’s hard to say when this will happen. Some research finds that babies can outgrow milk allergies by age three or four but other studies find that it’s later. The American College of Allergy, Asthma, & Immunology notes that about 80 percent of kids are likely to outgrow their milk allergy by age 16.

Fortunately, working with an allergist can help you understand your child’s specific allergy (blood tests measure antibodies but can also help identify whether or not someone will outgrow a milk allergy) and you can have tests done to retest the allergy as your baby gets older, according to your allergist’s recommendations.

Milk Protein Allergy (Lactose Intolerance) vs Milk Allergy

While a true milk allergy is an abnormal immune system response, lactose intolerance is not an allergy (the immune system is not involved), explains Anagnostou, but rather an enzymatic deficiency.

“Lactose intolerance is a common disorder and the result of an inability to digest lactose, milk sugar, because of low levels of the enzyme lactase,” she says. “Lactose is the main sugar in milk and milk products from mammals.”

While intolerance isn’t as serious as an allergy, it can still be uncomfortable. It often causes digestive issues and discomfort. Other symptoms of lactose intolerance include:

  • gas
  • diarrhea
  • cramps
  • bloating

Unlike a milk allergy, lactose intolerance also typically develops later, in early childhood to adolescence, explains Middleberg. Ultimately, though, playing a guessing game is not your best bet with allergies. So if you’re noticing symptoms, work with an allergist who can confirm a diagnosis and outline how to move forward.

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