Warring with an upset stomach after enjoying a cheese plate isn't just disappointing — it can be flat-out confusing. On the one hand, you may have an allergy to dairy, but maybe you're just lactose intolerant. Unfortunately, those conditions are not created equal, so knowing what sets them apart is important.
The big distinction? Allergies can be life-threatening and intolerances usually aren't, says Carla McGuire Davis, MD, associate professor of pediatrics in immunology, allergy, and rheumatology at Baylor College of Medicine. That's why you can usually eat quite a bit of a food to which you're intolerant before having a reaction, while just a few bites of a food that you're allergic to can set you off. Hopefully, you already know if you have a life-threatening food allergy (and keep an EpiPen or another type of injectable epinephrine handy). But, even non-fatal allergies can be severe — and they're still important to diagnose and manage, Dr. Davis says. And part of that management is watching out for changes in how your body reacts to certain foods. Unfortunately, it's possible to develop a food allergy well into adulthood.
That isn't where the differences between an allergy and intolerance end, though. While an allergy activates your immune system, an intolerance doesn't. For example, if you're lactose intolerant, that simply means your body doesn't have the necessary enzymes to digest dairy properly, which leads to diarrhea or an upset stomach anywhere from a half hour to two hours after ingesting the food. It sure isn't pleasant, but you can normally ride it out without any additional treatment.
But an allergic reaction usually involves more of a whole-body response within minutes or a few hours after eating and can include such symptoms as hives, swelling, itching, difficulty breathing, wheezing, dizziness, fainting, stomach pain, vomiting, diarrhea, or drops in blood pressure. You might experience just one of these symptoms, or a combination of a few of them, Dr. Davis says. Plus, she adds, even mild allergic reactions may warrant treatment, which may mean keeping an antihistamine like Benadryl in your bag.
If you think you may have a food allergy but aren't sure, don't play a guessing game with your symptoms (and certainly don't cut a whole group of foods out of your diet forever on a hunch). A board-certified allergist may be able to identify your problem through a skin or blood test, but neither of these are 100% accurate. If you take both tests and they come up with inconclusive results, your allergist may recommend an oral food challenge instead, in which you slowly eat a certain food in increasingly larger portions while your allergist observes your symptoms. Only once your doctor diagnoses the trigger of your allergy should you start avoiding a food completely (though it's probably a good idea to avoid the food until you see your doctor).
Bottom line? If you feel symptoms that could be attributed to a food allergy or intolerance, talk to your doctor as soon as you can, and they can help you figure out what's going on. It may sound like a pain to check these things out, but leading a cheese- or shrimp-free lifestyle will be well worth it if you end up feeling better.