What Are the Symptoms of Food Allergies?

When someone with a food allergy eats something they are allergic to, they may have an allergic reaction. This is because their immune system overreacts to a food or additive in a food and thinks it is a danger. This triggers a response that leads to symptoms.1

Symptoms may range from mild to severe and can even be life-threatening. Not all allergic reactions to food are the same. Someone can have a mild reaction 1 time and a more serious reaction the next.1

Food allergy symptoms can affect any part of the body, including:1

  • Skin
  • Gut
  • Heart
  • Lungs

Food allergy symptoms may first appear at any age but are most common in babies and children. You can have symptoms to a food you have been eating without issue for years.1

Gut symptoms

Gastrointestinal (GI or gut) issues are common in some food allergies. The GI system includes the mouth, throat, stomach, intestines, and bowels.1,3

Common GI symptoms include:1,3

  • Stomach cramps or pain
  • Diarrhea
  • Nausea
  • Vomiting
  • Mouth or throat inflammation or itching
  • Trouble swallowing, swelling of the tongue
  • Dehydration
  • Failure to thrive (in children)

It can be very hard to diagnose a food allergy from gut symptoms alone. Things like vomiting, diarrhea, and stomach pain may have different causes, including reflux, colic (in babies), food intolerance, and food poisoning.1,3

Food protein-induced enterocolitis syndrome (FPIES) is a rare, severe type of food allergy. It is delayed gut reaction caused by certain foods. FPIES causes repetitive vomiting, dehydration, and sometimes bloody diarrhea. It occurs mostly in babies 2 to 6 hours after consuming milk, soy, and some grains.1

It mostly happens when these children are being weaned or trying these foods for the first time. While FPIES is a food allergy, its symptoms are delayed and usually only results in gut trouble.1

Skin symptoms

Skin symptoms are common in many food allergies. About 40 percent of babies with the skin condition eczema (atopic dermatitis) are thought to have symptoms related to food allergies.3

Common skin symptoms of food allergies include:3

  • Hives
  • Swelling
  • Itching
  • Redness
  • Eczema

Heart symptoms

Signs that a food allergy is affecting the heart include:1

  • Weak pulse
  • Pale or blue coloring of the skin
  • Dizziness or fainting

Lung symptoms

Breathing problems can occur with food allergies but are less common than skin and gut symptoms. However, when they do occur, breathing issues may be a sign of anaphylaxis, a life-threatening condition. Common breathing symptoms of food allergies include:3

  • Coughing
  • Wheezing
  • Shortness of breath
  • Pale or blue coloring of the skin
  • Itchy or runny nose

Breathing issues may also be related to asthma, hay fever, or pet allergy rather than a food allergy.3

Anaphylaxis

Anaphylaxis is a severe and potentially life-threatening allergic reaction. It is dangerous because so many parts of the body react to an allergen at the same time.2

Reactions are usually fairly quick, usually within minutes of eating a food. However, it can happen hours later. Up to 20 percent of people can have a second reaction after the first episode has ended, without additional exposure to the food. This second reaction is called a biphasic reaction.2

Anaphylaxis is more likely to happen if:2

  • The person has symptoms involving the skin, nose, mouth, GI tract and either
    • Trouble breathing
    • Lower blood pressure
  • The person has any 2 of these symptoms:
    • Skin symptoms/swollen lips
    • Trouble breathing
    • Lower blood pressure
    • Gut symptoms (vomiting, diarrhea, stomach pain)
  • The person has low blood pressure, weakness, or fainting

If you think someone is in anaphylaxis, administer an emergency epinephrine auto-injector (EpiPen®) right away and call 9-1-1 for help.2

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Written by: Jaime R. Herndon | Last Reviewed: March 2022