What is a milk allergy?
A milk allergy is one of the most common types of food allergy. Your immune system overreacts to one or more of the proteins in milk you’ve ingested (eaten or drunk). Cow’s milk is the most common cause of a milk allergy. However, other types of animal milk, including goat’s milk and sheep’s milk, may cause your immune system to react.
You may have a true milk allergy as a result of an immune system reaction. There are also other reactions to foods as well, including:
- Milk protein intolerance in infants.
- Lactose intolerance in older children and adults.
A milk allergy can be deadly. If you have severe allergic reaction symptoms, such as trouble breathing, call 911 (or your local emergency number) or go to your nearest emergency room (ER) immediately.
Who does a milk allergy affect?
A milk allergy can affect anyone of any age. However, it’s more common in children under 16. Many children with a milk allergy will outgrow it. Nearly all babies with milk protein intolerance will outgrow those symptoms.
A milk allergy can develop in formula-fed and breastfed (chestfed) babies.
How common is a milk allergy?
A milk allergy is relatively common. Approximately 2% of all children in the U.S. have a milk allergy.
How does a milk allergy affect my body?
A milk allergy causes an allergic reaction in your body. An allergic reaction is your body’s response to an allergen.
If you have a milk allergy, your body responds by creating immunoglobulin E (IgE) after your first exposure to milk. IgE are antibodies your immune system makes. Your body makes many different types of IgE, which target specific kinds of allergens. IgE antibodies bind to mast cells (allergy cells) in your skin, respiratory tract (airways) and cardiovascular system. When they encounter milk proteins, they release histamine. Histamine is what causes your allergy symptoms.
IgE reactions happen quickly after ingesting milk. Reactions may include anaphylaxis, which is a severe allergic reaction that may cause death.
Other reactions to milk aren’t the result of the allergy antibody. Your reaction to milk is slower than an IgE-mediated reaction. It may take up to 48 hours to develop.
Milk is one of the most common triggers for a non-IgE reaction in babies. Most non-IgE food allergies, including milk, aren’t life-threatening. Reactions may include milk protein intolerance.
Why did I suddenly become allergic to milk?
Healthcare providers and medical researchers aren’t exactly sure why people suddenly develop a milk allergy.
Symptoms and Causes
What does a milk allergy look like?
An allergic reaction to milk usually begins within minutes of ingestion.
The severity of symptoms can vary between people. Mild symptoms may include:
- Nausea or vomiting.
- Abdominal pain.
- Tingling or swelling of your lips, tongue or throat.
Severe symptoms may include anaphylaxis. Without immediate treatment, anaphylaxis may result in death. Other severe symptoms may include:
- Chest tightness.
- Shortness of breath (dyspnea).
- Difficulty breathing.
- Difficulty swallowing (dysphagia).
- Rash (contact dermatitis).
- Drop in blood pressure (hypotension).
- Loss of consciousness (syncope).
What causes a milk allergy?
If you have a milk allergy, proteins in milk cause your immune system to overreact. There are two main types of protein in milk:
- Casein. Casein (kay-SEEN) is a byproduct of milk when it spoils and turns solid (curdles). You can also find it in cheese and yogurt. It accounts for about 80% of the protein in milk, and it gives milk its white color.
- Whey. Whey is a byproduct of the liquid part of milk when it curdles. It accounts for 20% of the protein in milk.
You may be allergic to one or both of the proteins.
Is a milk allergy contagious?
No, a milk allergy isn’t contagious. You can’t spread a milk allergy to another person.
Diagnosis and Tests
How do you know you are allergic to milk?
Talk to a healthcare provider if you have symptoms of a milk allergy. They may refer you to an allergist. An allergist is a healthcare provider who specializes in allergies. They can help you diagnose a milk allergy through testing.
Before conducting milk allergy tests, they may ask you questions, including:
- Does anyone else in your biological family have milk or other food allergies?
- Has a healthcare provider ever diagnosed you with food allergies?
- What are your symptoms?
- Do you take over-the-counter (OTC) medications to treat your symptoms?
- When do you notice your symptoms start to appear?
- Do you keep a food journal?
What tests will be done to diagnose a milk allergy?
An allergist may use different allergy tests to help diagnose a milk allergy based on your symptoms. These tests may include:
During a blood test, your allergist will use a thin needle (slightly smaller than the size of a standard earring post) to withdraw a small amount of blood from a vein in your arm. The blood sample goes to a laboratory. The lab adds milk proteins to your blood sample and measures the levels of IgE antibodies in it.
It may take a week or longer to get the results from a blood test.
Skin prick (scratch) test
This test exposes your body to small amounts of milk proteins.
Your allergist will first clean a test area of your skin with iodine or alcohol. The test area is usually on your forearm or upper back.
Your allergist will use a thin needle (lancet) to prick your skin with a small amount of liquid containing milk proteins. The lancet won’t go deep into your skin. You’ll only feel a tiny pinch, and you won’t bleed.
Some allergists may use a different method for skin testing. They place a droplet of liquid milk proteins on your skin. They then use a lancet to scratch your skin lightly. The droplets will enter your skin through the scratch. You’ll only feel slight discomfort, and you won’t bleed.
In addition to the milk allergens, the allergist will apply a positive and negative control to your skin. Controls help an allergist compare reactions. A positive control usually contains a histamine solution that causes an itchy, raised response on your skin within a few minutes. A negative control usually contains a saline solution that doesn’t cause a response.
After skin testing, you’ll wait 15 minutes. The allergist will then measure any discolored spots on your skin from the milk test or the controls with a ruler.
A skin prick test takes less than an hour.
Graded oral challenge
To definitively diagnose a milk allergy, your allergist may recommend a graded oral challenge (food challenge). This may be necessary if your history of food allergies and testing don’t match.
You’ll ingest a small amount of milk during a graded oral challenge. Your allergist will then observe you to see if a reaction develops. You may gradually ingest more milk to see how your body reacts.
A graded oral challenge may take up to four hours.
Management and Treatment
How is a milk allergy treated?
If you have a milk allergy, the only way to prevent a reaction is to avoid milk and products that contain milk. The United States Food and Drug Administration (FDA) requires all food manufacturers to list all common food allergens on food labels clearly.
You should also be aware that some products that don’t contain milk may share processing facilities with milk products. Look for labels that say, “Made in a facility that processes milk” or, “Manufactured on equipment shared with milk.”
As many children outgrow their milk allergy, treatment for this particular food allergen is often unnecessary. If your child doesn’t seem to be outgrowing their allergy, talk to an allergist about food desensitization treatments such as oral immunotherapy (OIT).
What foods and drinks should I avoid if I have a milk allergy?
If you have a milk allergy, you should avoid the following:
- Milk in all forms, including condensed, dry, evaporated and powdered milk.
- Milk from other mammals, including goats and sheep.
- Butter, including butter fat, butter oil and artificial butter flavor.
- Cottage cheese and curds.
- Custard, pudding and yogurt.
- Sour cream.
Many people with milk allergies can tolerate baked goods that contain milk, such as muffins and cake. Talk to a healthcare provider before trying any baked goods that have milk.
In rare cases, people with a milk allergy may have an allergic reaction after eating beef.
How can I get vitamins and nutrients if I don’t drink milk?
For many people, milk and milk products are important sources of vitamins and nutrients, such as vitamin D and calcium. If you have a milk allergy, it’s important to eat other foods that are rich in these vitamins and nutrients, such as spinach and broccoli.
Talk to a registered dietitian. They’ll help you eat a healthy, well-balanced diet.
What medications are used to treat a milk allergy?
If you have a milk allergy, a healthcare provider should prescribe you an epinephrine auto-injector (EpiPen®). Epinephrine quickly reverses the symptoms of anaphylaxis. The provider will explain when and how to use this device. You should keep your epinephrine injector with you at all times.
People with a milk intolerance or a non-IgE-mediated milk allergy don’t need a prescription for epinephrine.
What are the side effects of epinephrine injections?
Epinephrine injection side effects may include:
- Dry mouth.
- Increased sweating.
- Nausea and vomiting.
- Fatigue (weakness or tiredness).
These symptoms are typically mild and go away quickly.
How soon after treatment will I feel better?
An epinephrine injection starts to work immediately after you’ve injected yourself.
How can I prevent a milk allergy?
The best way to prevent an allergic reaction to milk is to strictly avoid milk in foods and drinks. Check the ingredient labels on all packaged foods. If you’re unsure if a product contains milk, avoid it until you can confirm with the manufacturer.
Introducing common food allergens to your baby early may prevent some food allergies. Talk to your child’s pediatrician about when to introduce products that contain cow’s milk.
You can’t prevent yourself from developing a milk intolerance or non-IgE-mediated milk allergy.
Outlook / Prognosis
What can I expect if I have a milk allergy?
Living with a milk allergy or having a child with a milk allergy can be challenging. Symptoms can range from mild to severe, and there’s no way to predict how your body will react. If you’ve had a mild allergic reaction to milk before, that doesn’t mean future exposures to milk will be mild — they may be severe. If you’ve had a severe allergic reaction to milk, you have a greater risk of having a severe reaction to milk again in the future.
However, with caution, you or your child can lead a fulfilling life. Healthcare providers can recommend resources, support groups and dietitians to help you with your day-to-day meals.
Babies and young children may outgrow a milk allergy as their digestive systems develop. Visit an allergist for annual testing to see if your child outgrows their milk allergy. Treatments are available for select people with a milk allergy.
How do I take care of myself if I have a milk allergy?
The following tips can help you take care of yourself if you have a milk allergy:
- Always be aware of what you’re eating and drinking.
- Check the nutrition labels before you eat a product, even if the food didn’t cause a reaction the last time you ate it. Manufacturers may change recipes and add milk.
- If your child has a milk allergy, teach them not to accept food from their friends or classmates.
- When dining out, notify your server that you have a milk allergy and ask detailed questions about ingredients and food preparation.
- Wear a medical alert bracelet with information about your milk allergy, or carry a medical alert card.
- Add your food allergy to your cell phone’s medical emergency setting or app.
- Talk to a healthcare provider about how to prepare for a reaction. They may prescribe an epinephrine auto-injector. You should carry it with you at all times in case you have a severe reaction.
When should I see a healthcare provider?
See a healthcare provider if you regularly have milk allergy symptoms or if you notice that your symptoms develop after ingesting milk.
When should I go to the ER?
Go to the ER or call 911 (or your local emergency number) if you start showing symptoms of anaphylaxis.
What questions should I ask a healthcare provider?
- How can you tell that I have a milk allergy?
- When can I introduce milk to my child?
- Will my child outgrow their milk allergy?
- Are there any support groups for people or parents of children who have milk allergies?
- Can you recommend a dietitian?
Frequently Asked Questions
Is a milk allergy the same as lactose intolerance?
No, a milk allergy isn’t the same as lactose intolerance.
Lactose intolerance (dairy intolerance) is the inability to digest lactose. Lactose is a sugar that’s in many dairy products. Lactose intolerance causes bloating, cramps and diarrhea after eating or drinking products that contain lactose. It’s more common in adults than babies and young children.
A milk allergy is when your immune system overreacts to one or more of the proteins in milk. It usually has more serious symptoms than lactose intolerance. Milk allergies are more common in babies and young children.
How do you test for dairy intolerance?
The most common test for dairy intolerance is the hydrogen breath test. The hydrogen breath test measures hydrogen gas levels when you breathe out (exhale). Lactose intolerance causes abnormal hydrogen levels in your gut, which the test measures.
A note from Cleveland Clinic
A milk allergy is a type of food allergy that occurs when your immune system mistakenly triggers a defensive response to proteins in milk. This response — or allergic reaction — can cause various symptoms, including hives, itching, nausea, vomiting, diarrhea and, in severe cases, anaphylaxis.
Not knowing what’s causing your symptoms can be frustrating, but a healthcare provider can help. They can conduct tests to confirm a milk allergy and prescribe medications. They can also refer you to a dietitian who can help you learn what’s best for you to eat and drink.
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