Your food doesn't agree with you: Is it an allergy?

You've likely eaten something in your lifetime that has upset your GI system. You may have been uncomfortable afterwards, with a vague idea that you don't feel well, or you may have had horrible vomiting or diarrhea. It may have lasted for days with you rushing repeatedly to the bathroom, or it might have passed a few short minutes after you took some over the counter medicine. If it happened just one time, you might have thought you experienced food poisoning. But if you've had the same problem more than once, (such as bloating and gassiness after a meal) it may be a food (not an infection) that is the cause. 

Does That Mean it's an Allergy?

Many food reactions exist: Coffee (or the caffeine in it) makes many people jittery. Greasy foods make some people nauseous. Carbonated beverages cause belching. None of these are examples of allergies; rather, they are common reactions that happen with specific foods–and they occur for a very large number of people. 

On the other hand, milk gives some people gas, discomfort or diarrhea. However, that is not an allergy either, but rather an intolerance (known as lactose intolerance) to the sugar found in dairy products.People's response to lactose can largely vary. Some people can tolerate the amount of lactose in yogurt and soft cheese, but can't drink much milk or ice cream. Others can't handle the small amounts found in a slice of cheese.  In contrast, anyone with a true milk allergy (a reaction to milk protein) can't take even the tiniest sip of milk without vomiting or developing a rash. 

How Can I Tell?

Specific IgE blood tests and skin tests will usually show a significant reaction if there's an allergy. But most allergists will also want to know that the person actually reacts to the food, so they will take a detailed history of past events or they might recommend a controlled exposure to that food in their office or in an emergency room, in case the person has a severe response. For allergies that provoke life-threatening reactions, like peanuts or shellfish, the allergist may recommend that the allergic person carry an EpiPen, so they can give themselves an emergency shot, should they unknowingly eat a food that even has a trace amount of the food they're allergic to.    Bottom line: Not every reaction to food is an allergy. If you experience severe vomiting, diarrhea, or rash after eating certain foods, IgE blood and skin tests can be done to determine if an allergy is present.