Food Allergies

What are food allergies?

Food allergies are reactions your body has to a food that it mistakenly thinks is harmful. In trying to protect you, it can cause hives, swelling, an upset stomach and difficulty breathing.

Food allergies can cause anaphylaxis, which can cause swelling in your airways or a severe drop in blood pressure. Call 911 or get to an emergency room immediately if you have face, mouth or throat swelling, difficulty breathing or swallowing, or feel faint.

Types of food allergies

Most commonly, “food allergies” refer to allergies to peanuts, tree nuts and other allergens that can cause immediate and often severe reactions. You might hear your provider call these “true allergies” or IgE-mediated allergies (for the IgE antibodies that cause them). Oral allergy syndrome is also a type of IgE-mediated allergy, but it causes a local reaction on your lips or in your mouth and rarely leads to anaphylaxis.

Non-IgE-mediated food reactions include:

• Food protein-induced enterocolitis syndrome (FPIES)
• Eosinophilic esophagitis
• Eosinophilic gastritis
• Food protein-induced proctitis

What are the most common food allergies?

The nine most common food allergies include:

• Peanuts
• Tree nuts (like almonds, walnuts, pistachios, hazelnuts, pecans, cashews and Brazil nuts)
• Milk
• Eggs
• Fish
• Shellfish
• Soy
• Wheat
• Sesame

These account for about 90% of all food allergies. But you can be allergic to any food.

What are the symptoms of food allergies?

Symptoms of food allergies include:

• Hives or skin rash
• Itchy skin
• Swelling of your face, lips, mouth or tongue
• Itchy mouth and throat
• Hoarse voice
• Difficulty swallowing
• Wheezing
• Shortness of breath or difficulty breathing
• Coughing
• Abdominal pain
• Vomiting
• Diarrhea
• Lightheadedness or loss of consciousness (fainting)
• Runny nose
• Sneezing

Symptoms of food allergies can be severe, even if you’ve only had a mild reaction in the past. Call 911 or go to the ER at the first sign of severe symptoms.

When would symptoms start if you have a food allergy?

Usually, you experience food allergy symptoms within two hours of eating.

What causes food allergies?

When you have a food allergy, your immune system mistakenly identifies a food protein as something harmful (as if it were a virus or bacteria). When you eat something you’re allergic to, it activates mechanisms meant to protect you and flush the allergen out of your system. This causes your symptoms, which can sometimes be life-threatening.

Who’s more likely to get food allergies?

You might be at higher risk for food allergies if:

• You have other allergies, like to pollen or dust.
• You have eczema or asthma. The tendency for people to have eczema, asthma and/or allergies together is called atopy.
• Someone else in your immediate family has allergies, asthma or eczema.

What are the complications of food allergies?

The most serious complication of food allergies is anaphylaxis, or swelling in multiple body systems that can cause uncontrolled vomiting, difficulty breathing and a severe drop in blood pressure (anaphylactic shock). Severe anaphylaxis can be fatal.

How are food allergies diagnosed?

Healthcare providers diagnose food allergies by asking about your symptoms and performing allergy testing. It’s a good idea to be prepared to tell your provider:

• The food that’s causing your symptoms (if you know).
• Whether the food is cooked or uncooked.
• How much of the food you’ve eaten when you have symptoms.
• What symptoms you experience and how severe they are.
• How long it takes between eating the food and symptoms starting.
• Any other factors that could’ve contributed to your symptoms. (Were you sick with viral illness at the time? Were you exposed to other allergens — like pollen — on the same day?)
• Whether you’ve treated the symptoms at home and whether the treatments helped.
• Whether the symptoms always happen after exposure to the food, or only sometimes.
• How long it’s been since you last had the symptoms.
• Whether you have other known allergies (to food, pollen, dust, pets, etc.).
• Whether you have eczema or asthma.
• Whether anyone else in your family has allergies, asthma or eczema.

What kind of testing do I need for a food allergy?

Tests might include:

• Allergy skin test. A provider pricks your skin with a tiny amount of allergen to see if you develop a reaction.
• Allergy blood test. A provider tests your blood for antibodies to your suspected allergens.
• Food challenge test. Under the supervision of your provider, you’ll eat small amounts of your suspected allergen to see if you have a reaction.

How are food allergies treated?

The best way to manage food allergies is to avoid your allergen. But there are a few treatment options that might reduce your risk of having an allergic reaction, including injections and oral and sublingual immunotherapy programs. You should also keep emergency medications, like epinephrine, on hand in case you accidentally eat something containing the food you’re allergic to.

Omalizumab injections

Your provider gives you omalizumab (Xolair®) injections once or twice a month (or your provider can train you to do it yourself). It can reduce your risk of having a reaction if you’re accidentally exposed to a food you’re allergic to.

Oral immunotherapy

Oral immunotherapy (OIT) is a program that can help you or your child build a tolerance to a food allergen. Your provider gives you increasing doses of your allergen over several months. The goal is to get to a point where you won’t have a reaction if you’re accidentally exposed to small amounts of the food you’re allergic to (called “bite-proof”). Some people can freely eat food they were once allergic to after OIT.

Sublingual immunotherapy

Sublingual immunotherapy (SLIT) works similarly to OIT in that you’re exposed to a small amount of your allergen every day to develop tolerance to it. Instead of eating the food you’re allergic to, you put a liquid or tablet under your tongue and let it dissolve. SLIT must be supervised by a healthcare provider for safety.

Emergency medications

If you’re accidentally exposed to your allergen and have an allergic reaction, your provider might give you or recommend you take:

• Your provider will recommend you carry an epinephrine auto-injector (EpiPen® or Auvi-Q®) to use at the first signs of a severe allergic reaction.
• Corticosteroids. Steroids reduce inflammation.
• Antihistamines can help stop or slow down allergic reactions. But providers don’t prescribe them to prevent reactions from food allergies.

Can you prevent food allergies?

While there’s no specific way to prevent food allergies, some strategies to reduce your child’s risk include:

• If you’re breastfeeding/chestfeeding, make peanuts and other common allergens a part of your regular diet (as long as you’re not allergic to them yourself).
• Ask your baby’s healthcare provider when and how to introduce new foods. They may recommend introducing allergens to your child earlier or under the supervision of a provider, depending on your child’s other health conditions.
• After you’ve safely introduced your child to potential allergens, continue feeding them a variety of foods that they aren’t allergic to, including nuts, milk and eggs. This might reduce their risk of developing an allergy later on.

What can I expect if I have a food allergy?

If you or your child have a food allergy, you’ll likely need to develop a habit of reading labels and avoiding foods that could contain the allergen. An allergist can talk to you about what treatment options are available and what to do if you have a reaction. They may recommend repeating allergy tests periodically to see if your child could’ve outgrown the allergy (or if you or your child have developed a tolerance through treatment).

Allergic reactions are unpredictable, so they can become more severe with each additional exposure. And there’s no way to test for how severe your reaction to a food might be without eating it. So, even if you’ve only had a minor reaction to a food in the past, you still need to be cautious in the future.

Can food allergies go away?

Sometimes. Many kids outgrow milk and egg allergies by age 6. But they rarely (less than 20% of the time) outgrow peanut, tree nut, shellfish or fish allergies.

How do I take care of myself?

To help prevent accidental exposure to a food you or your child is allergic to:

• Check the ingredient labels on premade foods. In the U.S., the label must state if a product contains any of the nine most common food allergens. Words to look for include “may contain” or “made on shared equipment.”
• Double-check labels when you buy food, when you put it away and before you eat it.
• Start talking to your child early about taking precautions about what they eat and not sharing food if they don’t know if it’s safe to eat.
• Be cautious at restaurants. Ask about whether the food contains your allergen but remember that they might not be able to make any guarantees.
• Let anyone who’s around your child know about their allergy and what foods are safe for them to eat.
• Talk to your child’s school or daycare about their allergy. Understand what plans they have in place to avoid accidental exposure.
• Carefully plan vacations and other time away from home. Bring safe foods with you or figure out in advance where you can go to eat.
• Ask your healthcare provider if you have any questions about what you can and can’t eat.

To be prepared in case of an allergic reaction:

• Always carry an epinephrine auto-injector with you. Ask your provider to show you exactly how to use it.
• Make sure your child’s school or daycare has an allergy action plan (Food Allergy & Anaphylaxis Emergency Care Plan) from your child’s provider on file. This details what to do if your child has an allergic reaction.
• Provide your child’s school or daycare with an epinephrine pen and any other medications your child might need.

When should I see my healthcare provider?

If you think you or your child have a food allergy, talk to a healthcare provider. They can refer you to a specialist and guide you on next steps.

When should I go to the ER?

Without medical treatment, allergic reactions can be life-threatening. Go to the ER or call 911 if you experience:

• Swelling of your face, lips, tongue or throat
• Difficulty breathing
• Chest tightness
• Hives all over your body
• Tingling hands, feet or lips
• Feeling weak, dizzy or faint
• Feeling of impending doom

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

• Are there any treatment options available?
• What should I do if I have an allergic reaction or am accidentally exposed?
• What are some strategies to avoid accidental exposure?
• How do I use this medication?
• When do I need epinephrine?
• Do you have an allergy action plan?

How common are food allergies?

Studies estimate between 6% and 11% of adults have food allergies. Food allergies affect around 8% of kids.