Types of Dairy Allergies And What Are The Symptoms?

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Approximately 3% of children in the Western world have a dairy allergy. And while many outgrow it, roughly 6.1 million adults in the U.S. still reported symptoms in 2019.

But if you are allergic to milk, what are the symptoms and treatment options? Let’s first explore what this allergy is, and what causes various reactions.

What is a dairy allergy?

A dairy allergy is an immune system response to the proteins in milk. If you’re allergic, upon consuming dairy products, your body starts to defend itself against what it mistakenly perceives as a threat.

This reaction might require avoiding all dairy, including foods like:

Butter
Cheese
Yogurt
Ice cream

Dairy allergies often emerge early–within six months of birth. While experts previously believed that most children outgrow milk allergies before reaching school age, recent research shows fewer than 20% do by age 4–although approximately 80% outgrow it by age 16.

For some sufferers, however, this allergy hits during adulthood–and remains lifelong.

What causes allergic reactions to dairy?

There are two primary allergenic proteins in milk–casein and whey. Casein makes up roughly 80% of cow’s milk protein. It’s found in the solid curds formed during the curdling process.

Whey, on the other hand, accounts for the remaining 20% of proteins; it’s what remains in the liquid portion of curdled milk. While most dairy allergy sufferers react to both casein and whey, some are sensitive only to one or the other.

Some studies show that specific types of whey and casein called alpha-lactalbumin and alpha-s1 casein, are most often linked to common allergic reactions like hives. Another type of whey, beta-lactoglobulin, can be the culprit behind severe anaphylaxis or anaphylactic shock.

Goat’s milk may be less allergenic for some with a dairy allergy due to its different protein structure and lower alpha-s1 casein content. However, many people still experience allergic reactions to it.

How to determine if you have a dairy allergy

Your doctor can determine whether you have a dairy allergy by:

Reviewing your medical history and any symptoms you may be experiencing
Conducting a skin prick test to check for immediate allergic reactions to milk proteins
Ordering a blood test that measures immunoglobulin E (IgE) antibodies, a protein produced by the immune system to combat substances it perceives as threats

Your doctor may also advise doing an elimination diet (avoiding all dairy products for 30 days) or an oral food challenge (OFC). During an OFC, you’ll gradually increase dairy consumption under medical supervision to test for reaction symptoms.

If you are allergic to milk, what are the symptoms?

A dairy allergy can trigger symptoms right away or up to three days afterward. These symptoms may range from mild discomfort to severe, potentially life-threatening situations.

There are two types of dairy allergies, each causing specific reactions:

IgE-mediated (acute) dairy allergy

An IgE-mediated milk allergy involves the immune system producing IgE antibodies to combat milk proteins, which trigger the release of histamines.

Symptoms of an IgE-mediated dairy allergy typically occur within minutes or up to two hours after consumption. The signs include:

Itchy, red skin or sudden rash
Swelling of the lips, cheeks, and/or eyes
Itching in the mouth and/or nose
Sneezing or nasal congestion
Coughing, wheezing, or shortness of breath
Nausea, vomiting, abdominal pain, or diarrhea containing blood

Infants may also experience symptoms of colic, such as a tense body, crying, and inconsolable distress with no apparent cause.

In severe cases, an IgE-mediated dairy allergy may lead to anaphylaxis, which can be life-threatening. Anaphylaxis is fast-acting, so if you start to notice difficulty breathing, seek medical attention immediately.

Non-IgE-mediated (delayed) dairy allergy

A non-IgE mediated milk allergy has a more delayed reaction–typically between four and 48 hours. But it is possible for symptoms to manifest three days after dairy consumption.

This type of allergic reaction does not involve IgE antibodies. While research is ongoing, experts believe T cells–a type of white blood cell that plays a pivotal role in immunity–trigger symptoms in response to dairy.

Some symptoms can be similar to those of IgE-mediated allergies but often appear more subtly and are mistaken for other conditions.

Here are some lesser-known symptoms of a non-IgE-mediated milk allergy:

1. Chronic skin issues

A growing body of research highlights a link between dairy consumption and acne. If you’re allergic, you may also experience a delayed reaction in the form of skin-related symptoms like eczema or rashes.

2. Joint pains

Research dating back to the mid-1980s has shown that elimination diets can improve joint pain–even in those with rheumatoid arthritis. This is likely because casein can trigger inflammation and pain, as well as irritation around the joints.

3. Breathing problems

Some studies suggest casein can also increase mucus production in the lungs and airways, potentially causing or exacerbating asthma or sinusitis symptoms over time.

If you have a non-IgE-mediated dairy allergy, you might also experience:

Coughing
Wheezing
Shortness of breath

If you observe these symptoms after consuming dairy, it’s important to consult your doctor.

4. Fatigue

Fatigue is another common delayed reaction to dairy, brought on by the body’s release of histamines to combat the allergen. Research shows histamines can cause inflammation, which contributes to feelings of tiredness by:

Inducing metabolic changes, including potential insulin resistance
Increasing oxidative stress
Changing functions in areas of the brain linked to fatigue

Histamines may impact sleep quality, which can leave you groggy. They also dilate blood vessels, lowering blood pressure and overall energy levels.

If you’ve been feeling fatigued, consult your doctor to rule out other potential causes–such as thyroid or hormonal imbalances–and to check for a dairy allergy.

5. Trouble losing weight

Because allergic reactions can trigger chronic inflammation and, potentially, insulin resistance, the body might experience higher insulin levels–which can lead to increased belly fat.

Furthermore, if your body has trouble digesting dairy, you may experience gas, bloating, and/or diarrhea, which can also disrupt digestion. This can impair calorie absorption and negatively impact your metabolism, making it more difficult to lose weight.

Mixed allergic reactions

Some people with a milk allergy experience both IgE-mediated and non-IgE-mediated symptoms. This means signs appear immediately after consuming cow’s milk protein and/or develop days later.

Related: Common Types of Allergy Tests

If you notice any of these symptoms, remove dairy from your diet for three weeks and monitor for any changes, recording them in a diary. Then, reintroduce dairy to see if symptoms return.

Treatment for dairy allergies

The primary treatment for milk allergies is simply avoiding dairy products. This involves reading food labels carefully, as many packaged foods contain some form of milk or butter. Also, watch out for terms like:

Whey
Curds
Milk by-products
Casein

If you accidentally consume dairy, consult your healthcare provider to assess whether treatments like antihistamines or inhalers are necessary, depending on the severity of your symptoms.

Oral immunotherapy

Alternatively, you can talk to your healthcare provider about oral immunotherapy (OIT). OIT is a newer approach that gradually increases tolerance to milk proteins by exposing you to controlled doses of them, potentially allowing you to eventually enjoy dairy products without reaction.

This treatment can last several months or years, and should only be conducted under medical supervision due to the risk of severe allergic reactions.

I’m allergic to milk protein; what can I eat?

There are a number of delicious dairy alternatives available these days, such as:

Milk made of almond, soy, oat, and rice
Yogurt made from coconut, almond, and soy
Vegan cheeses made from nuts or nutritional yeast
Ice creams using bases like coconut or cashew milk

Just keep in mind that a major concern with dairy-free diets is a deficiency in calcium, vitamin D, and/or protein. To ensure you’re getting enough of these vital nutrients, consider these tips:

Calcium: Enjoy fortified non-dairy milks, orange juice, leafy greens, and calcium-set tofu (tofu coagulated with calcium salts, offering similar calcium levels to dairy milk).
Vitamin D: Get 5-30 minutes of sun exposure without sunscreen (or with a minimal amount) a few times a week. Adjust this time based on your skin type, sensitivity, and the season.
Protein: Aside from meat, beans, nuts, seeds, and whole grains are excellent non-dairy sources of protein.

Also, talk to your doctor to determine whether you can enjoy cooked dairy products, as in bread.

Studies show that approximately 75% of children who are allergic to dairy can tolerate baked goods containing milk. This is because the baking process changes milk’s proteins, reducing their allergenicity.

Managing a dairy allergy doesn’t have to limit your culinary horizons–or compromise your health. By knowing the symptoms, working with your doctor, and utilizing dairy-free alternatives, you can enjoy a delicious, balanced diet that helps your body thrive.

References:

The US population-level burden of cow’s milk allergy – PMC.

Milk Allergy – an overview | ScienceDirect Topics.

Cow Milk Allergy – StatPearls – NCBI Bookshelf

Management of Cow’s Milk Allergy from an Immunological Perspective: What Are the Options? – PMC

Differentiating milk allergy (IgE and non-IgE mediated) from lactose intolerance: understanding the underlying mechanisms and presentations

‘Early Introduction’ of Cow’s Milk for Children with IgE-Mediated Cow’s Milk Protein Allergy: A Review of Current and Emerging Approaches for CMPA Management – PMC

Non–IgE- or Mixed IgE/Non–IgE-Mediated Gastrointestinal Food Allergies in the First Years of Life: Old and New Tools for Diagnosis – PMC

Cow’s milk-induced gastrointestinal disorders: From infancy to adulthood – PMC

Prediction of α-Lactalbumin and β-Lactoglobulin Composition of Aqueous Whey Solutions Using Fourier Transform Mid-Infrared Spectroscopy and Near-Infrared Spectroscopy

The Balance Between Caseins and Whey Proteins in Cow’s Milk Determines its Allergenicity

Goat Milk Allergy and a Potential Role for Goat Milk in Cow’s Milk Allergy – PMC