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.
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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:
- Shortness of breath
- 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.