Medically reviewed byCorinne Savides Happel, MD
Updated on April 25, 2023
Food allergies occur when your body mistakenly identifies and treats an ingested food as a threat, triggering an immune system response. Even eating a tiny amount of the offending food can lead to symptoms ranging from hives to swelling, stomach troubles to difficulty breathing, and even death. More than 90% of the most common food allergies are caused by one of eight allergens: dairy, eggs, wheat, soy, peanuts, tree nuts, fish, or shellfish.
Understanding Food Allergies
Frequently Asked Questions
What's the best way to test for food allergies?
Food allergies can be diagnosed via a combination of different methods: a blood test (IgE antibody test, known as immunoCAP or ELISA), a skin prick test, an elimination diet, or an oral challenge test. An oral challenge is often used when other testing is inconclusive, as it's the only test that can be used to actually confirm a food allergy, or to test if a food allergy has been outgrown.
Learn MoreHow Food Allergies Are Diagnosed
What causes food allergies?
Food allergies are caused by an immune system overreaction to a food the body has mistakenly deemed harmful. Experts aren't entirely sure why some people develop allergies and others don't. Environmental factors may play a role, as may family history. Having eczema, allergic rhinitis, or asthma makes you much more likely to have a food allergy, a phenomenon known as atopy.
Learn MoreFood Allergies: Causes and Risk Factors
Are food allergies genetic?
Genetics seem to play a big role in the development of food allergies, as having a parent/sibling with a food allergy or atopy (allergic rhinitis, asthma, or eczema) can greatly increase your chances. But genetics aren't the only factor. Environmental triggers, such as where you live and the regional cuisines you regularly eat, are also a big component in development.
How long does an allergic reaction to food last?
Allergic reactions may vary in length. Some allergic reactions may set in a few minutes after consuming the allergenic food, whereas others may appear up to two hours later. If hives or a rash develop, they may take a day or two to fully clear up. If you're experiencing any symptoms of anaphylaxis, such as throat constriction, dizziness, or shock, seek immediate medical help.
Learn MoreSigns and Symptoms of Food Allergies
Can food allergies cause a fever?
While food allergies can sometimes cause cold- and flu-like symptoms such as runny nose, sore throat, or sneezing, they do not typically cause a fever. Allergic rhinitis, also known as hay fever, is a common allergy, but it doesn't cause a fever.
Learn MoreSigns and Symptoms of Food Allergies
Can food allergies cause acne?
Food allergies are unlikely to cause acne, however, acne may be related to a food intolerance or sensitivity. A food intolerance is a condition in which the body has a reaction to a certain food, but the mechanism of this reaction is unknown and is not thought to be related to IgE that is involved in food allergies.
Learn MoreCauses and Risk Factors of Acne
Specific Food Allergies
What Are the Symptoms of a Peanut Allergy?
Tree Nut Allergy Diet Guide
Allergy to Wheat and Other Cereal Grains
Everything You Need to Know About Shellfish Allergies
What to Do if You Think You Could be Allergic to Eggs
Food Choices for a Soy-Free Diet
Overview of Gluten Allergy
Understanding Types of Milk Allergies
Here's How to Cope If You're Allergic to Fish
Key Terms
Anaphylaxis
A sudden and severe allergic reaction which can result in a significant drop in blood pressure, the onset of shock, and even death if not treated promptly. Anaphylaxis occurs as the result of an allergy affecting more than one body system at the same time, such as the skin and respiratory systems. Anaphylaxis comes on quickly and is a medical emergency requiring immediate care.
Atopic Dermatitis
Also known as atopic eczema, atopic dermatitis is an inflammatory skin condition marked by a dry, itchy, inflamed rash that may be acute or chronic. Eczema has many potential causes, including genetics and environmental factors. Food allergens are a common trigger of atopic dermatitis.
Histamine Intolerance
Not a true allergic reaction, histamine intolerance is a response to certain foods that contain high levels of histamine, a naturally occurring chemical. Histamine can be found in alcohol, aged cheeses, and other fermented foods, as well as spinach and tomatoes. Migraine headaches are a classic symptom of histamine intolerance
Immune System
The body's defense system to protect you from infection and harmful microorganisms. The immune system is capable of waging complex responses to various viruses, bacteria, and pathogens, but in some cases, a certain trigger may set off an immune reaction when one is not warranted, as in the case of food allergies.
The Link Between Other Conditions and Food Allergies
Mild to Severe Dairy Allergy Symptoms
What Are Food Allergies?
How to Identify a Quinoa Allergy
What to Know About an Eggplant Allergy
How to Identify a Tamarind Allergy
How to Identify an Olive Oil Allergy
Everything You Need to Know About a Cilantro Allergy
Are You Allergic to Green Tea?
Everything You Need to Know About Egg Intolerance
What Spices Should You Avoid With a Nut Allergy?
Everything You Need to Know About Citrus Allergies
Everything You Should Know About a Banana Allergy
What You Need to Know About Cashew Allergies
How to Identify a Chicken Allergy
Symptoms of Food Intolerance
Can You Be Allergic to Wine?
Causes and Risk Factors of Food Intolerance
What to Know About Nightshade Intolerance
The Best and Worst Foods for Allergies
Corn Allergy Overview
What You Need to Know About Kiwi Allergies
This Asthma Drug Can Prevent Severe Food Allergies from Peanuts, Milk, and Eggs
How Toothpaste Could Help People Overcome Peanut Allergies
7 Food Allergies You Didn't Know About
Can You Be Allergic to Potatoes?
How to Identify a Vinegar Allergy
What You Need to Know About a Spinach Allergy
What Does It Mean to Have a Black Pepper Allergy?
Everything You Need to Know About a Cherry Allergy
How Food Intolerance Is Treated
Iodine Allergy: What You Should Know
What Is Oral Allergy Syndrome?
Signs You Have a Pear Allergy
Everything You Need to Know About a Beer Allergy
What You Need to Know About an Avocado Allergy
What Is a Yogurt Allergy?
Living With Eosinophilic Esophagitis
How Eosinophilic Esophagitis Is Treated
How Eosinophilic Esophagitis Is Diagnosed
Symptoms of Eosinophilic Esophagitis
Do I Have a Sugar Allergy or Sugar Intolerance?
What Is a Wheat Allergy?
Hazelnut Allergy: Symptoms and Treatment
The Connection Between Annatto and Nut Allergies
Could You Be Allergic to Cinnamon?
Alcohol Allergies and Intolerance
What Is Histamine Intolerance?
Is It Possible to Be Allergic to Chocolate?
New or Ongoing Egg Allergy Symptoms
Milk Allergy Symptoms: Could You Be Allergic to Milk?
Differences Between Food Sensitivity and Food Intolerance
Eosinophilic Esophagitis (EoE) Symptoms and Diagnosis
Why People Claim to Have Food Allergies
How to Reduce Cross-Contamination If You Have Food Allergies
23 Non-Food Places You May Find Hidden Peanuts
The Coconut Allergy Diet Guide
Lactose Intolerance
Best At-Home Food Sensitivity Tests
What to Do if Your Baby Is Allergic to Formula
Cleaning in School for Kids With a Peanut Allergy
More In Allergies
Page Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
U.S. Department of Agriculture. Food allergies.
American College of Allergy, Asthma, and Immunology. Food allergy diagnosis. Updated February 12, 2019.
Weidinger S, Novak N. Atopic dermatitis. Lancet. 2016 Mar 12;387(10023):1109-22. doi:10.1016/S0140-6736(15)00149-X.
Additional Reading
American College of Asthma, Allergy, & Immunology. Allergy symptoms: fever.
Emons, J.A.M., Gerth van Wijk, R. Food allergy and asthma: is there a link?. Curr Treat Options Allergy 5, 436–444 (2018). doi:10.1007/s40521-018-0185-1
National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee on Food Allergies: Global Burden, Causes, Treatment, Prevention, and Public Policy; Oria MP, Stallings VA, editors. Finding a Path to Safety in Food Allergy: Assessment of the Global Burden, Causes, Prevention, Management, and Public Policy. Washington (DC): National Academies Press (US); 2016 Nov 30. 5. Potential genetic and environmental determinants of food allergy risk and possible prevention strategies.