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A Gastroenterologist and Allergist Share How To Tell if You Have a Dairy Sensitivity, Allergy, or Something Else

Sharon Feiereisen

November 27, 2021

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Going dairy-free has become an increasingly buzzy topic in many circles, and not just those that include vegans. “While about two and a half percent of the general population have a food allergy, about 15 to 20 percent have a food sensitivity or intolerance,” says Purvi Parikh, MD, an allergist with the Allergy & Asthma Network. But when we’re talking about dairy specifically, numbers skyrocket. “Somewhere in the range of 60 to 70 percent of the general population is lactose intolerant, and that number is over 80 percent in certain parts of the world such as Asia, according to gastroenterologist Akash Goel, MD, assistant professor of medicine in the gastroenterology and hepatology division at Weill Cornell.

Experts In This Article

Purvi Parikh, MD, allergist, immunologist, and medical advisor with the Allergy & Asthma Network

The difference between dairy allergy symptoms and lactose intolerance symptoms

According to Dr. Parikh, those afflicted with a dairy allergy generally experience a rash, itching, and swelling within 30 to 60 minutes of ingesting dairy. "This may or may not be accompanied by nausea, vomiting, stomach cramps, diarrhea, dizziness, and loss of consciousness," she says. When you’re dealing with a sensitivity, such as lactose intolerance, symptoms are limited to gas, bloating, stomach cramps, and diarrhea, which appear within 30 minutes to up to two hours after eating dairy. (By the way dairy is one of the top foods that cause phlegm after eating. The food can trigger increased mucus production as your body tries to protect itself.)

“There is overlap in terms of the possible gastrointestinal symptoms, but the key differentiator is with allergies you’ll also get those skin symptoms,” Dr. Parikh explains. "Regardless, if you're experiencing any of the symptoms above, it’s important to see a board-certified allergist to determine if you have a true allergy or not, as allergies can be life threatening. Sensitivities may be unpleasant, but they are not usually dangerous."

Dairy allergies and sensitivities are caused by different things, too

“Food sensitivity is a side effect of a food or difficulty digesting or metabolizing a food,” says Dr. Parikh. A sensitivity to dairy is, specifically, a sensitivity to lactose.

“Lactose is a natural sugar found in dairy products,” says Dr. Goel. “When this sugar is not broken down, it gets fermented by gut bacteria, with gas by products leading to the downstream consequences of the symptoms discussed.” A dairy allergy, by contrast, is an immune response. “Since the presentation for cow's milk allergy is fairly dramatic, these are typically diagnosed and found in infancy, and are fairly common—roughly two percent of babies may have a cow's milk allergy. The immune system in this case is typically reacting to one of the proteins in dairy such as whey or casein,” Dr. Goel adds.

But according to the doctor, there is a caveat: Just because you don’t feel great after having Greek yogurt or cheese doesn’t mean you have a sensitivity to dairy. “If there is a fever or chills involved, it could be an infection,” says Dr. Parikh. “If pain is sudden, sharp, or severe and painful to the touch, it could be an emergency such as appendicitis, ovarian torsion/rupture, pelvic inflammatory disease or ectopic pregnancy and rupture.” Or, maybe you just ate too much brie. (It happens to the best of us!)

By the way, if you're suddenly stressing about prevention, don't. The only proven way to reduce the risk of developing a food allergy, based on the landmark LEAP study, is early introduction to the common allergens before the age of one.

The good news? There are so many delicious dairy-free foods on the market—ideal for those with or without a dairy intolerance. Ice cream? Check. Cheese? Check. Milk? Check. Check. Check.

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