Have you ever had a bad reaction or felt rough after eating something and wondered if you’re allergic to it?

The problem could be due to a food allergy or intolerance. They sound similar but are two different types of reactions.

Food allergies are caused by an immune system reaction with symptoms that can affect different parts of the body. Common food allergy symptoms include tingling or itching in the mouth, skin rash or hives and a stuffy, runny nose. Reactions can appear in a matter of minutes or can take hours. The most severe is anaphylaxis, which is life-threatening. Symptoms of anaphylaxis include dizziness, trouble breathing and a fast heartbeat.

Food intolerance symptoms tend to come on more gradually and typically affect the digestive system. These can include bloating, diarrhea or stomach irritation. They are uncomfortable but not life-threatening. Another difference is that a small amount of food eaten, inhaled or that you come into contact with can trigger an allergic reaction, whereas symptoms of food intolerance tend to be more likely if the food is eaten in large portions or frequently.

If you think that you have a food allergy or intolerance, talk with your primary care provider about it. Symptoms of allergies and intolerances can be similar, especially if it’s an allergy causing problems in the digestive tract like diarrhea. Or it might not be food hypersensitivity at all but something else, such as food poisoning or celiac disease.

Some people know immediately if a food causes problems and others aren’t sure. Lactose (milk sugar) and sulfites added to foods for preservation (or naturally occurring) are two common ingredients that many people do not tolerate well. The eight most common food allergens are:

>> Peanuts (a legume).

>> Tree nuts (pecans, walnuts).

>> Shellfish (such as shrimp, oysters).

>> Fish.

>> Milk.

>> Eggs.

>> Soy.

>> Wheat.

According to Food and Drug Administration requirements, the nutrition facts label on food products must indicate if the item was made with one of the eight common allergens or was processed in a factory handling these foods where cross-contamination could have occurred. On these labels, the name of the food source appears in parenthesis following the name of the food allergen in the list of ingredients if the name of the food source of the major allergen does not appear elsewhere in the ingredient statement.

For example:

“Ingredients: Enriched flour (wheat flour, malted barley, niacin, reduced iron, thiamin mononitrate, riboflavin, folic acid), sugar, high fructose corn syrup, whey (milk), eggs, vanilla.”

Alternatively, the word "Contains" followed by the name of the food source from which food allergen is from will appear after or next to the list of ingredients.

If you have a food intolerance, you can try limiting your portion of the food and still might be able to enjoy it, like a cold glass of milk, for example. Often people with an intolerance can have smaller amounts of the food every three to four days without having issues, but some do better eliminating the food item completely.

Keeping a food journal is helpful in determining the food(s) that cause a reaction. This entails recording what you eat and when you have a reaction over a specified time period and looking for patterns. Your primary care provider or a registered dietitian/nutritionist can help you identify patterns. An elimination diet can also be useful to determining which foods are causing problems. This means all suspected foods are eliminated from the diet and then reintroduced, one at a time, to see which causes symptoms. If your care provider determines you could have a food allergy, they might order skin or blood tests.

Once you know for certain that you are allergic to a food, it will need to be completely eliminated from your diet to avoid reactions. Sometimes, after avoiding the food for a couple of years, people have lost the allergy. Those prone to anaphylaxis however, might be prescribed an epinephrine auto-injector pen for use in emergencies. These should be injected into the middle of the outer thigh at the first signs of anaphylaxis, which include:

>> Skin reactions, such as hives, itching, and flushed or pale skin.

>> Low blood pressure (hypotension).

>> Constriction of the airway and a swollen tongue or throat, which can cause wheezing and trouble breathing.

>> A weak and rapid pulse.

>> Nausea, vomiting or diarrhea.

>> Dizziness or fainting.

After using an epinephrine auto-injector, you should visit an emergency department immediately for examination and monitoring, as symptoms can return.

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Anita Longan, RDN/LD, CDE, BC-ADM, is a registered dietitian nutritionist and diabetes educator at the Diabetes and Nutrition Institute at the HopeHealth Medical Plaza in Florence. She provides a variety of diabetes and nutrition programs and counseling.