Milk Allergy vs. Lactose Intolerance: Understanding the Difference

May 24, 2022

Milk Allergy vs. Lactose Intolerance: Understanding the Difference

6 minute read

Eating an entire gallon of ice cream on a Friday night will be enough to make you feel guilty in more ways than one. But if just a single bite from that Rocky Road sends you down a rocky path of stomach pain, you might have lactose intolerance. Or maybe you’re allergic.

How do you know whether or not you’re lactose intolerant or allergic to milk? Some key differences between the two are important to know before you dig into your Ben and Jerry’s pint one more time. Here’s everything you need to know.

What Is a Milk Allergy?

A milk allergy is a type of food allergy, and it’s among the eight most common allergens. True food allergies are caused by an immune system malfunction in which the body perceives the proteins found in milk to be harmful.

If you have a milk allergy and consume cow’s milk proteins, your body produces something called immunoglobulin E, or IgE antibodies. These signal your immune system to release chemicals that elicit the symptoms of an allergic reaction, such as a closed throat, swelling, coughing, or sneezing, and can also lead to anaphylaxis which is a life-threatening reaction causing a low blood pressure, difficulty breathing, and possible throat closure.

There are two main types of milk proteins in cow’s milk that can cause a reaction: whey and casein. Whey is found in the liquid part of milk that remains after it curdles, whereas casein is found in the solid part of milk, or the curd. You may be allergic to one or both of these types of proteins.

Milk is also one of the most common causes of food protein-induced enterocolitis syndrome, or FPIES. This is a delayed reaction to consuming an allergen, often resulting in nausea, abdominal cramps, and vomiting hours after the allergen has been ingested.

What Is Lactose Intolerance?

Lactose intolerance is a problem with the way the body digests milk, cheese, or yogurt. This is the major difference between intolerance and allergies: intolerance is a digestive system disorder, whereas an allergy is a problem with the immune system.

Lactose intolerance occurs when your small intestine does not make enough of a specific digestive enzyme called lactase. Lactase is what breaks down lactose, which is the sugar found in animal milk, especially cows.

Intolerance to milk and dairy products often runs in families. In these cases, your body simply makes less of the enzyme that breaks down lactose. However, an intolerance can also form after injuries, disease, or infection.

How Do the Symptoms Differ?

Lactose intolerance and milk allergies can present themselves with similar symptoms. For that reason, it can be difficult to tell the difference between the two. Both lactose intolerance and milk allergies share the following possible symptoms:

  • Abdominal pain
  • Nausea
  • Bloating
  • Diarrhea or loose stools
  • Gas

However, milk allergies tend to have more severe symptoms compared to lactose intolerance. The following symptoms are usually only seen with a true milk allergy:

  • Hives
  • Wheezing
  • Coughing or shortness of breath
  • Itching or tingling around the mouth
  • Swelling of the lips, tongue, or throat
  • Runny nose or nasal congestion
  • Watery eyes

As a general rule of thumb, the symptoms of lactose intolerance are only related to issues with the digestive tract. In other words, you shouldn’t feel anything more than an upset stomach or some gas. However, a milk allergy needs to be taken more seriously, as the symptoms can affect your health.

In some cases, individuals with a severe milk allergy might experience a life-threatening reaction called anaphylaxis, which requires immediate medical attention.

How Do the Treatments Differ?

Since lactose intolerance and milk allergies have different causes and symptoms, it only makes sense that they also require different treatments.

Treating Milk Allergies

Treating milk allergies is highly dependent on the type and severity of symptoms. We cannot predict the symptoms of an allergy. You may have mild symptoms or you may have a reaction called anaphylaxis.

If a milk allergy causes anaphylaxis, you’ll need a shot of epinephrine from an epinephrine autoinjector. Symptoms of anaphylaxis can include a closed throat, difficulty breathing, vomiting, hives, or loss of consciousness.

If you have a known dairy allergy, you should always have an epinephrine autoinjector with you. After getting your epinephrine shot, you still should seek emergency care even if your symptoms start to improve.

It should be noted that most individuals outgrow their milk allergies once they reach adulthood. The Mayo Clinic estimates that 60-80% of children will outgrow milk allergies by adulthood.

Treating Lactose Intolerance

Lactose intolerance can make you feel extremely uncomfortable, and stomach pain or bloating can often be embarrassing. However, it doesn’t pose much of a risk to your health. For that reason, the only true way to “treat” it is by just letting it run its course.

Most of the remedies for lactose intolerance focus on diluting the symptoms. You may want to try lactase enzyme tablets, which is a supplementary version of the enzyme that breaks down the lactose in dairy products.

Since people with lactose intolerance often do not make enough of this enzyme naturally, taking these before eating dairy may reduce the symptoms.

Additionally, some people have found success in taking probiotic supplements to reduce lactose intolerance pain. Probiotics are “good” bacteria that may help foster proper digestive health.

One of the only treatments that can help for both milk allergies and intolerance is to avoid animal milk. Choose non-dairy alternatives, such as almond milk or oat milk.

How Can I Know if I Have Lactose Intolerance or a Milk Allergy?

Since the symptoms can sometimes seem similar, it can be hard to tell exactly which one of these conditions is the source of your discomfort.

Different diagnostic tests can reveal the source. A lactose intolerance test will have you ingest a dairy product before testing your blood two hours later. If your glucose levels do not rise, it means you are not properly digesting the lactose in milk.

You can take an allergy test to reveal if you’re allergic. A skin prick test is a common allergy test that entails an allergist placing tiny droplets of different allergens under your skin, usually on your back. If you are allergic to the substance, your skin will react by showing a raised red welt. You can also go in for blood testing to check the level of IgE antibodies you have to milk. If you have a certain amount of IgE antibodies to milk, then you are allergic.

In Conclusion

Milk allergies and lactose intolerance have similar symptoms, like diarrhea, stomach cramps, and bloating. However, lactose intolerance is a disorder of the digestive tract, whereas milk allergies are problems with the immune system.

For that reason, the symptoms of lactose intolerance are pretty much exclusive to the digestive tract, like cramps and gas. Milk allergies can have more serious effects, like difficulty breathing or loss of consciousness.

Treating lactose intolerance usually involves just treating the symptoms. You can even just take lactase enzymes to help break down the proteins in cow’s milk to reduce your symptoms. Depending on the severity of the allergic reaction, you may need some more heavy-handed treatment like an epinephrine shot.

If you are concerned about an allergy to dairy, you can talk to one of our board certified allergists online by booking a consult.


Food Allergies | FDA.

Lactase tablets or capsules | Cleveland Clinic

Milk allergy - Diagnosis and treatment | Mayo Clinic


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