These involve an antibody called immunoglobulin E (IgE). Reactions are typically fast and can range from mild to severe, often affecting multiple areas of the body.

Symptoms usually appear within minutes and may include:

• swelling of the face, lips, or eyes
• hives or welts
• stomach pain or vomiting.

Anaphylaxis is a severe, life-threatening IgE-mediated reaction that can affect breathing and circulation. 

Symptoms may include:

• trouble breathing or speaking
• swollen tongue or throat
• wheezing or persistent coughing
• pale skin, dizziness, or fainting
• floppiness (especially in babies and toddlers).

These allergies do not involve IgE antibodies and mainly affect the digestive system. They do not cause anaphylaxis and are generally not life-threatening.

Symptoms are usually delayed, appearing four hours to several days after eating the allergen. One exception is food protein-induced enterocolitis syndrome (FPIES), which can cause symptoms within four hours.

Common non-IgE-mediated food allergies include:

• food protein-induced enterocolitis syndrome (FPIES)
• food protein-induced allergic proctocolitis (FPIAP)
• food protein-induced enteropathy (FPE)
• coeliac disease.

Mixed-IgE/Non-IgE-mediated food allergy symptoms can take hours to days, and in rare cases weeks to appear. Symptoms can appear as common digestive issues including:

• vomiting
• reflux-like symptoms
• redness and irritation of the skin.  

Mixed-IgE and non-IgE-mediated food allergies include:

• eosinophilic esophagitis (EoE)
• atopic dermatitis.