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Signs of Allergies

Food allergies are the most likely allergies to cause nausea and/or vomiting. A reaction occurs when your immune system overreacts to a food or a substance in a food, incorrectly identifying it as a danger and triggering a protective response.

You don’t normally associate seasonal allergies with nausea — for good reason. Nausea and vomiting are rarely, if ever, symptoms of a seasonal allergy. Typical seasonal allergy symptoms include sneezing, runny nose, itchy eyes and maybe a rash.


Find an allergist

If you encounter something you’re allergic to, your immune system considers the substance dangerous and releases a chemical called histamine to counteract it. Histamine can cause a variety of symptoms, including rash, headache, sneezing, runny nose and swelling — and in the case of food allergies, nausea, vomiting and diarrhea. If the allergen is something you breathe in, your reaction will probably affect your eyes, nose and lungs. If you eat the allergen, you’re more likely to have symptoms in your mouth, stomach and intestines.

Other food allergy symptoms include:

  • Hives
  • Shortness of breath
  • Wheezing
  • Repetitive cough
  • Shock or collapse of the circulatory system
  • Tight, hoarse throat; trouble swallowing
  • Swelling of the tongue, affecting the ability to talk or breathe
  • Weak pulse
  • Pale or blue skin
  • Dizziness or feeling faint

The most severe reaction, known as anaphylaxis, can be life-threatening and requires immediate treatment with an epinephrine auto injector followed by emergency treatment.


If you have food allergies that can lead to symptoms such as nausea and vomiting, it’s important to know which foods trigger your symptoms.

The eight most common food allergens are:

How to Get Tested

If you think you might have a food allergy that could lead to nausea and vomiting, you should be tested by an allergist. Getting tested by a board-certified allergist is the first step to helping you deal with your allergy and avoid your triggers. An allergist will take a detailed medical history and review your symptoms to determine whether your symptoms are triggered by an allergy to food, medications, insect stings or something else.  

Allergy tests are both convenient and accurate. When combined with a detailed medical history, allergy testing can identify the specific things that trigger your allergic reactions. Testing also helps your allergist determine whether you have a food intolerance or a food allergy, which both can cause stomach upset.

Many people may think they have a food allergy when what they really are experiencing is food intolerance. Food intolerance can often mimic a food allergy, causing nausea and vomiting, but is not life-threatening. The best way to determine whether you are experiencing a food allergy is to see an allergist for testing. An allergist will help you develop an action plan to deal with whatever allergies or intolerances you may have.

It Could Also Be…

There are many things that can cause nausea and vomiting. If your allergist rules out severe allergies, ask what else might be causing your nausea, such as:

  • Concussion or brain injury
  • Early stages of pregnancy
  • Eating disorder
  • Emotional stress
  • Food poisoning
  • Heart attack
  • Infections such as stomach flu
  • Intense pain
  • Motion sickness
  • Reaction to a medication
  • Reaction to certain smells or odors
  • Ulcers

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