Here’s how to know your lactose intolerance is a full blown allergy

There’s nothing fun about discovering an itchy rash on your skin or rushing to the bathroom after devouring a delicious cheese plate or milkshake. But how do you know if you’re dealing with dairy allergy symptoms, lactose intolerance, or something else entirely?

Without allergy testing, it can be tough to parse the difference. Our immune system’s response to food allergens, and specifically to dairy, is a little bit on a spectrum, so there’s no easy way to just lump dairy allergies under one category.

A dairy allergy (or a cow’s milk allergy) typically first appears in infants or children. In fact, it’s the most common food allergy in kids. But you could develop an intolerance to dairy products at any age.

Symptoms of a dairy allergy can range from mild to life-threatening, so it’s important to know what to look out for and when to reach out to your doctor for help. If you suspect you or a loved one could have a dairy allergy, here’s everything you need to know, including five signs you should never ignore.

What is a dairy allergy, exactly?

A dairy allergy is an adverse immune reaction to a food protein. There are two milk proteins that can trigger this out-of-whack immune response: casein (which is found in milk curds) and whey (which is found in the liquid part of milk). You could be allergic to one or both of them. And some bad news: If you’re allergic to cow’s milk, you’re likely allergic to sheep’s and goat’s milk too. Typically, allergic reactions arise soon after you ingest dairy products.

There’s also a subset of people who have a chronic inflammatory disease called eosinophilic esophagitis (EoE). In this case, a food allergy – most often to cow’s milk – triggers swelling that specifically affects the esophagus, the tube that connects your mouth to your stomach.


When your immune system releases histamine, it recruits a whole host of immune cells and together they trigger massive, runaway inflammation and irritation throughout the body. Here’s what could follow and how to deal.

Swelling in your face and throat or wheezing

Anaphylaxis is a severe and potentially life-threatening allergic reaction that can happen fast after you ingest dairy. A swollen face, throat, and mouth that could cause the sensation of a lump in your throat or difficulty breathing are some of the most urgent signs that you need emergency medical care. Treatment includes an epinephrine shot (EpiPen), an exam at the ER, and a follow-up appointment with a specialist to ensure you’re prepared to prevent and manage potential reactions in the future.

A rapid pulse

If you feel like your heart’s racing or fluttering in your chest after you’ve ingested dairy, this is another potential sign of anaphylaxis. In this case, it’s essential to reach out for help immediately.

Dizziness, light-headedness, or loss of consciousness

Wooziness or even fainting could also indicate anaphylaxis. Again, head to the emergency room or call for emergency transport immediately.

Skin hives

An itchy rash can also be a sign of a dairy allergy, arising anywhere within minutes to two to three hours after exposure. If you have hives on your face or body – which look like a flush of red bumps – along with other signs of a serious allergic reaction like trouble breathing or respiratory issues, seek medical attention immediately. Otherwise, schedule an appointment with a dermatologist to determine what could be irritating your skin. Regardless of the source, the first-line treatment for hives usually includes antihistamines, medications that block the effects of the histamine triggering the hives, or a steroid medication, which reduces inflammation.

Nausea, vomiting, and diarrhea

When a wave of inflammation strikes your G.I. tract due to a dairy allergy, this can trigger an upset stomach, vomiting, or even bloody stool (especially in infants). In particular, FPIES can trigger severe vomiting and diarrhea. So, if you have a baby who can’t stop throwing up after drinking formula several hours before, head to the doctor for an exam.

Keep in mind: This is also where there’s some overlap in symptoms with lactose intolerance. If a wave of stomach issues arises, be sure to stay hydrated to replace any fluids you may lose through diarrhea or vomiting. Eat bland, low-fibre foods like crackers, toast, rice, or chicken until you feel a bit better – and avoid any questionable foods you recently ate until you get checked out by your doctor.