The Quick Beginner’s Guide to Understanding Food Allergies

That's it. ·

Whether you are new food allergy parent or are looking for more information on how to help someone you know with a food allergy, this guide will cover the basics you need to better understand food allergies.

Almonds in a cup


A food allergy is caused when the body’s immune system overreacts to a substance in a food, usually a protein, your body sees as harmful and creates a defense system to fight it. Symptoms can occur very fast, even immediately, and can be mild up-to severe. Some mild symptoms include itchy eyes or a runny nose and may subside without treatment. Other symptoms include swelling of the tongue and throat, hives, vomiting, abdominal cramps and diarrhea. In severe cases, symptoms can be life-threatening and progress to severe anaphylaxis with low blood pressure and loss of consciousness. Antihistamines will help with symptoms such as itching and congestion. Severe reactions, however, need to be treated promptly with an epinephrine injection, which begins to work immediately and is currently the only effective treatment option. As of now, there are ongoing clinical trials and hope for therapies that will manage food allergies in the future but none that are currently approved.

Common Allergens

There are multiple foods that are known to cause food allergies. In the U.S., there are 8 foods that make up the most common food allergens. These are:

  • Milk
  • Eggs
  • Peanuts
  • Tree nuts (includes pistachios, almonds, walnuts, cashews)
  • Fish
  • Shellfish
  • Soy
  • Wheat

Food allergies tend to run in families but it is impossible to know if it will be inherited or if siblings will also have an allergy. Food allergies can appear at any age but are slightly more common in young children. Most develop early in life and many are outgrown. Currently, there is not enough evidence to conclude that dietary interventions such as limiting specific foods (such as peanuts and eggs) during pregnancy or breastfeeding beyond 4-6 months of age prevents food allergies. Even deferring the introduction of solid foods beyond 4 to 6 months of age does not appear to provide significant protection from developing food allergies.

Some people experience symptoms of itchy mouth and throat after eating uncooked fruits or vegetables. This may be related to an oral allergy syndrome, in which the person is having a reaction to the pollen of the food, not the food itself. Heating the food destroys the allergen and therefore can be eaten with no issues.

Food allergy vs Food intolerance

A food allergy should not be confused with a food intolerance. An intolerance occurs when your body is unable to digest a specific food component. For example, someone who is lactose intolerant (lacking the enzyme to break down natural sugars in milk), but not allergic, may be able to eat small amounts of dairy. Symptoms can include abdominal cramping and discomfort, gas, and diarrhea. These symptoms, however, are not life threatening. Since food allergy symptoms overlap with symptoms of other medical conditions, it is important to have a food allergy confirmed by a qualified medical professional, such as a board-certified allergist. This will also avoid any unnecessary diet restrictions.


Currently there is no cure for food allergies and the only way to prevent them is to completely avoid the food that causes the reaction and any product that contains the food as an ingredient. While shopping or eating away from home, it is recommended to check labels every single time as even a familiar product can have a label and recipe change without notice. Even items you don’t think firsthand are an issue, such as cosmetics, can contain allergens. Also, allergy-causing foods might be listed under other names.

To make it easier to help avoid allergens, the FDA (U.S. Food and Drug Administration) requires manufacturers to specify on food labels in clear language if the product contains any of the 8 major allergens (milk, eggs, peanuts, tree nuts, fish, shellfish, soy, or wheat). This does not apply however to items regulated by the US Department of Agriculture (meat, poultry and certain egg products) or for alcoholic beverages such as spirits, wine and beer. If unsure of an ingredient, feel free to call the manufacturer and ask for details.

If there is any physical contact with the allergen itself, studies have shown that by thoroughly handwashing with soap and water and cleaning the surface with detergent can remove the allergen. Please note that soap and water must be used, hand sanitizers will not work to remove the allergen from the skin.

Cross-contact vs Cross-contamination

Not only is it crucial to make sure to read food labels and menus carefully but also be aware of cross-contact. An example of cross-contact can involve handling a non-allergy food using the same cutting-board that was used to handle the allergen. Eating and even touching a tiny amount of the offending food can cause life-threatening reactions.The terms cross-contamination and cross-contact are sometimes used interchangeably but are slightly different. Cross-contamination involves the transfer of harmful bacteria from one food to another. These harmful bacteria can be killed through cooking properly per food safety guidelines. An allergen, however, remains dangerous even after cooking.

Tips for Eating Out

When going out to eat, it’s especially important to inform the person who is preparing of any allergies (this could be at a daycare, school, coworkers, restaurant, caregivers, friends and family). At a supermarket, bulk-bins, buffets and salad bars should be avoided as there is a high chance of cross-contact in these areas. Take known safe items (such as That’s it. Fruit Bars) for back-up and check restaurants website online to double check the ingredient lists before you go. It is also important to educate a child on their own food allergies so that they are safe and empowered to manage their own allergies.

Related Blogs

A Quick Guide to Navigating the Top 8 Allergens

Tips on Managing Food Allergies in Your Daily Life

Healthy, Allergen-Free Summer Snack Alternatives


“Symptoms of an Allergic Reaction to Food.” Food Allergy Research & Education,

“Food Allergies.” EatRight, (2019). Reducing the Risk of Food Allergies. [online] Available at: [Accessed 12 Nov. 2019].

Wolfram, Taylor. “Food Allergies and Intolerances.” EatRight,

Begun, Rachel. “Preventing Cross-Contact at Home.” EatRight,