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Problems With Dairy: Is It An Allergy, Intolerance, Or Sensitivity?

Stefano Guandalini, MD

Medically reviewed by


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If milk, cheese, or ice cream causes you to have uncomfortable symptoms, know that you’re not alone. About two-thirds of the world’s population is lactose intolerant, and milk is one of the nine most common food allergens. But since there are several different types of reactions you can have to milk, it can be tricky to figure out what exactly the problem is. In this article, I’ll explain the difference between lactose intolerance and allergy, the signs and symptoms of each, and how to uncover whether milk is the problem. Plus, I’ll cover what to do if you discover dairy is a no-go for you. 

Dairy sensitivity vs. lactose intolerance vs. milk allergy: Is there a difference? 

Defining Dairy sensitivity

There’s lots of talk about “dairy sensitivity,” but this term essentially means a non-allergic reaction to dairy products. Usually, when we talk about dairy sensitivity, we mean lactose intolerance, as it is far more prevalent than an allergy to a dairy protein (whey or casein). 

Overall, I’m not a fan of the term dairy sensitivity. It’s possible to have a reaction non-allergic, non-intolerance-related reaction to milk because it’s spoiled or you had too much of it. But the only medical reasons a person can’t tolerate dairy products are lactose intolerance and milk allergy. 

Defining Lactose intolerance 

Having a lactose intolerance means you don’t have enough of the digestive enzyme lactase to digest lactose, a sugar found in milk and many dairy products. Lactose intolerance usually starts later in life, and depending on the cause, may or may not be reversible. 

Defining Milk allergy 

If you’re allergic to milk, it means you have an immune system reaction in response to consuming milk. There are two main proteins in milk: casein and whey. Some people are allergic to both, and others are allergic to just one or the other. Whey is the more allergenic of the two. You can find out whether you’re allergic to whey, casein, or both through IgE blood testing, but it’s more important to know if you have a milk protein allergy in general, since casein and whey are both present in milk products. 

Usually, milk allergy crops up in infancy or early childhood, and may resolve by the time a person reaches adulthood. Interestingly, if a child is allergic to fresh milk but can tolerate baked milk without a reaction, they’re more likely to outgrow their milk allergy, according to FARE, a top food-allergy non-profit organization. Milk allergies aren’t as common as lactose intolerance, but food allergy in general is common, affecting about 32 million Americans

What is lactose intolerance?

Unlike food allergies, food intolerances don’t involve the immune system. In fact, it’s important to know that milk allergy and lactose intolerance aren’t related. Instead, food intolerances are food reactions that typically happen in the digestive tract. Lactose intolerance is a prime example of that. 

Lactose intolerance, explained

Lactose is a type of sugar that’s mainly found in dairy and milk products. In order to break down and digest lactose, we need an enzyme called lactase, which is produced in the small intestine. Problem is, a large part of the population is genetically pre-programmed to lose their lactase activity after a certain age (usually not before the age of 8-9). Thus, many of us become lactose intolerant by the time we reach adulthood.

Prevalence of lactose intolerance varies depending on which part of the world you’re looking at, but in North America, it’s very common. Fun fact: Lactose intolerance is most common in the Middle East, and least common in Western, Southern, and Northern Europe. 

Is lactose intolerance curable?

When lactose intolerance happens for genetic reasons, it can’t be reversed. But sometimes, lactose intolerance can be caused by conditions like Crohn’s disease, celiac disease, intestinal infections, and bacterial overgrowth. In these cases, these conditions cause lactase production to decrease, so treating the condition could mean lactase production starts up again, and symptoms of lactose intolerance lessen or resolve. 

Symptoms of lactose intolerance

The most common symptoms of lactose intolerance include: 

  • Diarrhea
  • Nausea
  • Stomach cramps
  • Bloating
  • Gas

Generally, the intensity of the symptoms experienced correlates with the amount of dairy eaten. So some people with lactose intolerance may be able to eat a small amount of dairy without discomfort, but once they go above a certain threshold, they experience symptoms. 

How to find out if you have lactose intolerance

There are several ways your doctor might test you for lactose intolerance. Usually, the first step is to consume a high-lactose beverage. Then, your doctor will either measure the:

  • Glucose in your blood (this was the first test of this type to be developed, now rarely used); 
  • Hydrogen levels in your breath (known as a hydrogen breath test, most widely and commonly used for diagnosis);
  • Acid in your stool (this is the least reliable method; in fact, there could be other reasons causing a low stool pH/excess acidity).

As an alternative, your doctor may also request a blood test that does not require any ingestion of lactose, as it checks for a specific genetic trait: the presence of the gene called Lactase persistence gene. This is the gene encoding for the enzyme Lactase, and its absence implies you will lose (or have already lost) your ability to digest lactose at some point in your life due to genetic pre-programming. 

If you want to be tested for lactose intolerance, you should follow up with your primary care doctor, allergist, or gastroenterologist. 

But often, people with reactions to dairy find it easier to challenge themselves to “test” for lactose intolerance at home — provided the symptoms they experience aren’t extreme. This can be done by either taking a lactase pill before eating dairy, or consuming a dairy product where lactose has been removed by the previous addition of lactase (lactose-free milk). In either case, if you no longer have a reaction to dairy, then you can be reasonably sure that lactose intolerance is the problem, rather than a dairy allergy. 

Managing lactose intolerance is relatively simple

One way to manage lactose intolerance is to avoid all lactose-containing dairy products. At the same time, many people find that they can tolerate certain dairy products that aren’t completely free from lactose, but have very low levels of lactose. 


Dairy Products with Lactose (contains milk protein)
Low-Lactose Dairy Products (contains milk protein)
Lactose-Free Products (contains milk protein)
(no lactose or milk protein)
  • Cow milk
  • Goat milk
  • Sheep milk
  • Buttermilk
  • Cream
  • Cheese
  • Ice cream
  • Yogurt
  • Cottage cheese
  • Ricotta
  • Hard, aged cheeses (cheddar, Swiss, parmesan)
  • Greek yogurt, and other yogurts with live active cultures
  • Kefir
  • Quark
  • Cultured cottage cheese
  • Butter
  • Sherbet
  • Lactose-free milk, yogurt, or ice cream
  • Non-dairy milk and yogurt (soy, almond, oat, etc.)
  • Vegan ice cream
  • Nut cheese and other vegan cheeses

More good news if you’re lactose intolerant: Ingesting lactose will cause temporary symptoms, but won’t result in any inflammation or permanent damage. And if you want to eat something with lactose in it, taking a digestive enzyme supplement that contains lactase with your meal can help break down the lactose, which means you won’t experience symptoms.  

Milk with lactase added is usually labeled “lactose-free,” and is also a suitable option for people with lactose intolerance. Food products that don’t contain any dairy, such as those marked “dairy-free” and “vegan,” are also safe choices for people with lactose intolerance.  

What does it mean to have a milk allergy? 

As mentioned earlier, having a milk allergy means you have an immune system reaction when you consume milk. You can be allergic to whey (more likely), casein, or both. 

Symptoms of milk allergy

Signs of milk allergy are consistent with food allergy symptoms overall. Reactions can range from mild to severe, and symptoms may include:

  • Nausea
  • Vomiting
  • Abdominal pain
  • Diarrhea
  • Skin swelling, hives, and rashes
  • Coughing, wheezing
  • Stuffy nose and mucus congestion (rhinorrhea) 
  • Swelling of the airways

A severe allergic reaction to milk might also result in anaphylaxis, a life-threatening reaction that involves many organs at the same time. It’s important to note that allergic reactions are hard to predict, and a previously mild reaction can sometimes turn into a dangerous one. If you think you might have a milk allergy (or know you have one), it needs to be taken seriously. 

Types of milk protein allergy

Milk protein allergy can be mediated by IgE, but can also be non-IgE mediated, or even mixed. While IgE-mediated are the most common, it’s important to note that issues with dairy aren’t always as clear-cut as a typical food allergy or lactose intolerance.

Immunoglobulin E (IgE) mediated milk protein allergy

If you have a true milk protein allergy, it means that when you consume milk (or dairy products that contain milk protein), your immune system is stimulated to produce immunoglobulin E (IgE) antibodies to specifically fight against it. 

Non-IgE mediated milk protein allergy

It’s also possible to have a non-IgE mediated allergy to milk protein. In this case, your immune system will react to consuming milk, but IgE antibodies aren’t involved. One example of this is FPIES (Food Protein Induced EnteroColitis Syndrome), a serious condition that’s typically diagnosed in infants, and is usually a reaction to protein found in milk, soy, eggs or cereal grains.

Mixed IgE mediated allergy

Lastly, you could have a condition that’s either IgE- or non-IgE-mediated. Eosinophilic Esophagitis (EOE), also called “the asthma of the esophagus,” is one example. Milk is thought to be one of the most common triggers for EOE, and an elimination diet that removes it may help resolve symptoms.

How to find out if you’re allergic to milk

To find out if you’re truly allergic to milk, the gold standard test is an IgE food allergy blood test. This test will tell you if you have an IgE-mediated milk allergy. During or after testing, it’s a good idea to work with a certified allergist for management. This is important regardless of whether your test results are positive or negative for milk allergy. 

If your test is positive, an allergist can help you come up with an appropriate treatment plan, so you know what to do if you have a reaction. If your test is negative, they can help figure out whether a different food is causing your symptoms, you have a non-IgE mediated allergy, or you have an intolerance, which can’t be diagnosed by IgE blood testing. An allergist might also have you try an elimination diet and/or run an oral food challenge to confirm the results of your blood test. 

Managing milk allergy

If you have a true milk allergy, it’s important to remove milk and all dairy products from your diet. Milk proteins are found in a surprising number of foods you wouldn’t expect, so you’ll need to get into the habit of carefully reading food labels to check that you’re not accidentally consuming milk. You can find a comprehensive list of ingredients to watch out for on FARE’s website

Where else can you get the nutrients found in milk?

Several key vitamins, minerals, and nutrients are found in milk. Whether you need to skip milk because of an intolerance or allergy, it’s important to ensure you’re getting these nutrients elsewhere. 


Calcium is an important mineral for strong bones, and has many other crucial functions, such as playing a role in muscle movement and blood flow. Milk and dairy products are one of the biggest sources of calcium, so those who don’t drink milk for one reason or another may end up not getting enough. However, there are many good non-dairy sources of calcium. They include kale, broccoli, chinese cabbage, and fish with soft bones that you eat (like sardines and salmon). Tofu, soy milk, rice milk, orange juice and breakfast cereals are also sometimes fortified with calcium. Read the nutrition label to check! 


Milk is a great source of protein, but there are many other foods you can use to bulk up your protein intake if milk isn’t an option for you. Fish, eggs, poultry, beef, and pork are all high-protein foods. In addition, many plant-based foods are rich sources not only of protein, but also of minerals and fiber—without the saturated fat found in most animal proteins. They include lentils, chickpeas, white beans, black beans, split peas, pinto beans, kidney beans, navy beans, soybeans, and soy products like tofu, tempeh, and edamame.

Vitamin D

Vitamin D is a hot topic these days due to its link to COVID-19 risk, and deficiency can pose major health risks like excessive fatigue and reduced immunity. The sun is our primary source of vitamin D, but in the United States, milk and dairy products are fortified with vitamin D. Accordingly, research shows milk and dairy products are one of the primary sources of dietary vitamin D among Americans. Some lactose and dairy-free milks may be fortified with vitamin D, but it can also be found in fatty fish, fish liver oils, and egg yolks. In addition, pickled herring, canned salmon, and sardines are excellent natural sources.

Vitamin B12

This vitamin is only found in animal sources, so aside from milk, your best bet for getting it is eating foods like fish (especially tuna, sardines, trout), meat, and eggs. Some cereals and nutritional yeasts are also fortified with vitamin B12.  

What about supplements? 

All of these nutrients are also available in supplement form. If you’re concerned you’re not meeting your needs, touch base with your doctor or a registered dietitian, who can advise on the appropriate supplement dosage for your situation. 

The bottom line

If you experience symptoms when you consume products that contain milk, it’s worth getting to the bottom of them. Lactose intolerance is incredibly common and in many cases can be managed on your own at home after consulting with a gastroenterologist. On the other hand, milk allergy is a serious condition that needs careful diagnosis and management from a certified allergist. Depending on the root of the problem, you may need to remove dairy and milk from your diet, but there are luckily many dairy and milk alternatives available. 

Updated on
August 11, 2022
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