Food allergies and food intolerances are incredibly common – adults and kids alike can be affected. However, they are not the same and it’s important to understand how they’re different from each other.

Read on to learn more about what a food allergy is and how allergies are different than intolerances. We’ll also discuss the nine most common food allergies, the allergens that cause them, how to recognize the symptoms of an allergic reaction to food, and what to do if you experience them.

What are food allergies?

Food allergies occur when your body’s immune system overreacts to certain foods or a substance in a food, also called food allergens. Your immune system identifies this food allergen as dangerous, triggering an allergic reaction.

Food allergy symptoms that people experience can range from mild to very severe. And something that may have triggered a mild reaction at one point may trigger a more severe reaction if you come back in contact with that food or substance again.

Food intolerances are often confused with food allergies. While they both have some of the same physical signs and symptoms, they affect our bodies in different ways.

How a food allergy is different than a food intolerance

The main difference between food allergies and food intolerance, or food sensitivity, is how your body is affected. A true food allergy affects your body’s immune system, and even small amounts of an allergen can cause your body to have a reaction. It can cause rash, swelling, difficulty breathing and other symptoms.

A food intolerance often only affects your digestive system where your body has a harder time digesting certain foods. And while the symptoms like bloating, gas or upset stomach can be uncomfortable, they’re not life-threatening.

Lactose can cause lactose intolerance, not allergies

Your body uses digestive enzymes to break down food, and if your body lacks a certain enzyme, it may be less able to digest some foods. A common example of this is lactose intolerance. Lactose is a sugar that’s in milk, and people with lactose intolerance lack lactase, the enzyme that breaks down lactose, which makes milk more difficult for you to digest, but doesn’t cause an allergic reaction.

Wheat sensitivity is different than a wheat allergy

Gluten sensitivity, or gluten intolerance, describes when you feel tired, nauseous or bloated after eating foods that contain gluten, a protein found in wheat, barley, rye and other grains.

Celiac disease is an autoimmune disease where ingesting gluten can lead to damage in the small intestine. This is a more serious condition that is diagnosed by a blood test and often a follow-up biopsy to confirm the diagnosis.

These are different from a wheat allergy, however. Gluten causes a reaction in your digestive system with a wheat intolerance or celiac disease, and a true wheat allergy causes a reaction to your immune system.

Possible signs and symptoms of food allergies

Symptoms of food allergies vary in each person and range from very mild to life-threatening. It’s important to know the signs of an allergic reaction so you can protect yourself and your loved ones.

An allergen may trigger some mild to moderate symptoms of an allergic reaction internally and externally, including:

  • Tingly or itchy feeling in your mouth
  • Flushed (red) skin or allergic rash
  • Hives (raised white bumps on your skin)
  • Face, tongue or lip swelling
  • Abdominal cramping
  • Vomiting and/or diarrhea
  • Feeling dizzy and/or lightheaded
  • Difficulty breathing or wheezing

What to do in case you have an allergic reaction to food

If any of these symptoms occur when eating certain foods, it’s important to reach out to your primary care doctor. They may refer you to an allergist, where you’ll be tested to identify the allergen causing the allergic reaction. They’ll work with you to create a personalized treatment plan to manage your allergy.

What you should do in case of an emergency reaction to food

A food allergy can trigger anaphylaxis, which is incredibly serious and potentially life-threatening. If you experience anaphylaxis, seek emergency help immediately by calling 911 or go to a hospital as soon as possible. Symptoms of anaphylaxis can include:

  • Tightened airways
  • Throat and tongue swelling
  • Rapid pulse
  • A drop in blood pressure
  • Dizziness and/or loss of consciousness

Using an epinephrine auto-injector (EpiPen) for anaphylactic reactions

Research shows that up to 5% of people with food allergies experience anaphylaxis. Epinephrine, an adrenaline shot that relaxes muscles in your airway and tightens blood vessels, is the first treatment that should be used in case of anaphylaxis.

If know you have severe reactions to certain allergens, your doctor may prescribe an epinephrine auto-injector, like an EpiPen or an AUVI-Q auto-injector, to be carried with you at all times.

How to properly use an epinephrine auto-injector

There are several epinephrine auto-injectors that can be prescribed if you have a severe food allergy to certain allergens: Epi-Pen, AUVI-Q and Adrenaclick. If you are prescribed an auto-injector, it’s important to follow the instructions exactly as written, but all three generally work the same way.

  1. Prepare the auto-injector: Remove it from its outer case, hold it in your fist and remove the safety cap.
  2. Administer the shot: Place the needle side perpendicular against your outer thigh and push firmly until you hear a click. Hold it in place for 2-3 seconds (depending on the type of auto-injector you’re using) and remove.

Seek emergency medical treatment right away after using an auto-injector. While epinephrine likely won’t cause any issues, it’s possible that severe symptoms could come back and further treatment may be needed.

How are food allergens regulated?

The U.S. Food & Drug Administration (FDA) recognizes that food allergies are very common and can be extremely dangerous. The FDA regulates the food industry and requires that companies list ingredients on their food labels, with more specific labeling requirements for items that may contain allergens. They also provide guidance to consumers on how to manage allergen hazards in food and other items that may contain allergens.

The FDA regularly inspects facilities and samples products to ensure food allergens are properly labeled, and to ensure that there’s no cross-contamination (the unintentional addition of an allergen to a product) during manufacturing. If issues are found, the FDA may issue recalls and even seize products that violate their regulations.

Top 9 most common food allergens

Your body could have an allergic reaction to almost anything, both indoor and outdoor. There are many different common types of allergies caused by allergens, including environmental allergies like a reaction to pollen, dust and animal dander, seasonal allergies and allergies to medications. But some of the most common allergies people experience are food allergies. The FDA has identified the following items as the nine most common food allergies:

1. Milk

Milk allergies are most common in children, and most often, the allergen is cow’s milk – but milk from goats, sheep and other animals can also cause an allergic reaction. A milk allergy is different from lactose intolerance. Lactose intolerance involves your digestive system, causing bloating, gas or diarrhea, and a true milk allergy involves your body’s immune system.

Why might you be allergic to milk? Your body may identify certain proteins in milk as harmful, and an allergic reaction may occur. The two main proteins (allergens) that may cause a reaction are casein (found in milk curd) and whey (liquid leftover after milk curdles). These proteins are found in milk and many processed foods, as well.

Like with most allergies, there isn’t a cure or treatment. Avoiding milk and milk products is the only way to avoid an allergic reaction. Read food labels carefully, as even products that are labeled as dairy free or nondairy may still have allergens. Some people with a milk allergy can tolerate foods that have been highly processed and heated, but they should talk with their doctor before doing so.

2. Eggs

An egg allergy occurs when your body reacts to a protein in the egg white, egg yolk or both – most allergens in eggs occur in the egg white. The three main allergens in eggs are ovalbumin, ovomucoid and ovotransferrin. Egg allergies commonly occur in children, and since allergies can evolve over time, most kids outgrow an egg allergy by the age of five. Symptoms of an allergy include hives, swelling and shortness of breath.

Some people with an egg allergy may be able to consume foods containing eggs if they’ve been heated to more than 350 degrees Fahrenheit for more than 30 minutes. However, not all the allergens in eggs are able to be broken down by heat, so depending on which protein you’re allergic to, you may not be able to eat baked eggs – but you should talk to your doctor first.

It’s important to read labels and ask questions if you’re allergic to eggs. Even some foods labeled egg free, like mayo or salad dressing, may contain egg proteins.

Foods with wheat proteins like breads and pastas are usually pretty easy to identify. But other products that may contain wheat can include certain cosmetics, bath products and more. So, staying away from wheat and wheat products is the only way to avoid an allergic reaction. Also, some foods like soy sauce or dairy products may contain wheat and you may not realize it, so keep a close eye on ingredients in anything you eat.

4. Peanuts

Peanut allergies are a common cause of the most severe allergic reactions. Allergies to peanuts typically occur early on in life and are usually lifelong. Only a small percentage of children with a peanut allergy outgrow it over time. Symptoms of an allergic reaction can include skin rash, hives and anaphylaxis.

Peanut allergies are different from tree nut allergies – peanuts are legumes and are closely related to beans, not tree nuts like almonds or cashews.

Peanut oral immunotherapy or peanut desensitization is being developed as a treatment for peanut allergies. Immunotherapy describes a technique in which a person with an allergy is exposed to increasing amounts of the allergen daily until their immune system is trained not to have a severe reaction.

Immunotherapy for peanut allergies is a developing and evolving area of medicine. Right now, there’s one FDA-approved treatment that works in much the same way as immunotherapy. But instead of using actual peanuts, it uses a powder derived from peanuts that contains controlled amounts of allergens.

Over the course of treatment, the dose of the powder is gradually increased, training the immune system to not have a severe reaction to the allergens. Although reactions to peanuts can become less severe, this is a treatment that doesn’t make the allergy go away entirely.

5. Soy

An allergy to soy is most common in infants and young children. Most children outgrow the allergy, but some are allergic for life. Soybeans, like peanuts, are a legume, so people with a soy allergy may also be allergic to peanuts. But people with a peanut allergy rarely have a reaction to soy.

Soy is in more than soy sauce and tofu, it is an ingredient in many processed foods. So it’s important to always read labels. With soy, be especially careful with Asian cuisine as soy is often used in food from Asian cultures.

There are some types of soy that people with soy allergies may be able to eat, like highly refined soy oil and soy lecithin.

6. Tree nuts

An allergy to tree nuts like almonds, cashews or hazelnuts generally starts early in life and only a small percentage of people outgrow tree nut allergies over time. If you’re allergic to one specific tree nut, you may not be allergic to others. But some nuts, like pecans and walnuts are closely related, so if you are allergic to one, you may be allergic to both.

If you have a tree nut allergy, that doesn’t necessarily mean you’ll have a peanut allergy, but it is possible, and symptoms of an allergic reaction to tree nuts can be similar to peanuts. Avoiding tree nuts and products with tree nuts in them, such as nut butters and nut oils, is the only way to avoid an allergic reaction.

It’s important to read labels and understand that tree nuts could not only be in the actual product but may come in contact with products during manufacturing. It’s also important to identify foods that may be hidden sources of tree nut proteins, including flavored coffee, cereals and cookies. Even personal hygiene products may contain tree nut allergens and you may not realize it.

7. Shellfish

There are several types of shellfish that you could be allergic to, including crustaceans like crabs, shrimp and lobster, and mollusks such as clams, oysters and scallops. Crustacean allergy is the most common type. Some people with a shellfish allergy may be allergic to all shellfish, while others may only react to certain kinds. Symptoms of a shellfish allergy can include hives and swelling of the face.

Read labels for packaged food, and make sure food wasn’t prepared with pans, oils or utensils used for shellfish when eating out. Also, avoid any place where shellfish is prepared – even the steam from cooking shellfish can cause an allergic reaction.

8. Fish

An allergy to fish, such as tuna or salmon, can develop at any age, even if you’ve eaten fish before. People who have a fish allergy may be allergic to some types of fish and not others, as different species of fish have different allergens.

Fish allergies are different from shellfish allergies, and if you’re allergic to fish, you won’t necessarily be allergic to shellfish. Like with shellfish allergies, it’s important to read labels to avoid any products with fish in them. And when eating out, make sure food was prepared without coming into any contact with fish. Also, avoid sitting where fish is being cooked, as an allergic reaction can occur from the steam from cooking the fish.

9. Sesame

Sesame is commonly known as a hidden allergen because it’s not always listed on labels of items that contain it. Sesame can be found in food such as chips, crackers, dipping sauce and dressings, but it can also be in nonfood items, including medications, nutrition supplements and cosmetics.

It’s an allergy that most commonly occurs in children, and only a small percentage grow out of it. Many children who are allergic to sesame may also have tree nut and peanut allergies. Symptoms of an allergy to sesame can range from allergic skin rash to anaphylaxis.

There’s been an increase in sesame allergies in recent years due to manufacturers’ growing use of sesame seeds and sesame oil in their products, and because popularity in international cuisine – like Middle Eastern and Asian – has been on the rise. Avoiding items that may contain sesame seeds or sesame oil is the only way to prevent an allergic reaction.

What happens if you keep eating foods you’re allergic to?

It’s a common misconception that if you keep exposing yourself to an allergen that you’re allergic to, you can eliminate the food allergy. This is dangerous because allergic reactions are all very different, and exposure to the same allergen can cause mild, moderate or even life-threatening symptoms. The only way to avoid an allergic reaction is to remove the allergen from your diet completely.

How long does a food allergy reaction last?

No two allergic reactions are exactly alike. It depends on the severity of your symptoms, and whether the allergen came into contact with your skin, or if it was ingested, injected or inhaled. It may be a few hours or a few days for your symptoms to go away.

Understanding allergic reactions and their severity

If you have an allergy, it’s important to monitor it closely, even if you only experience mild to moderate symptoms when you come into contact with the allergen. If your reaction is severe, like anaphylaxis, always take immediate action and call 911, or go to the hospital as soon as possible.

There is no cure for allergies, but they are manageable. If you think you, your child or your baby may have an allergy, visit your primary care provider who may refer you to one of our food allergy doctors. They can help to diagnose and figure out a treatment plan that works best for you.