Food allergies may either lead to immediate symptoms or may only trigger symptoms after repeated intake of a specific food item. Food allergies are most commonly mediated by the antibody immunoglobulin (IgE), when symptoms usually appear within a few seconds or minutes.

Symptoms

Symptoms of food allergies include:
 

• A skin rash called urticaria that appears raised and is severely itchy. Urticaria may be confined to one part of the body or spread all over it. In some individuals, the skin may only become red and itchy and not raised.
• Angioedema or swelling of the eyes, lips, mouth, throat, palate (roof of the mouth), tongue and face.
• Constriction of the throat and difficulty in breathing.
• Swelling of the larynx or voice box that may lead to hoarseness and further difficulty in breathing. There may be a cough and a tightness of the chest due to constricted breathing and some patients may develop an audible wheeze.
• Nausea, vomiting and diarrhea along with abdominal bloating, pain and cramps, with blood or mucus present in stools.
• Flu-like symptoms including runny nose, nasal blockage, sneezing and a watering or redness of the eyes (allergic conjunctivitis).
• Dizziness
• Delayed allergic reactions may include atopic eczema that leads to the formation of itchy, dry and cracked skin lesions.

Allergy in babies

• Babies with food allergies (especially milk) cry due to colic and abdominal spasms. The baby may suffer from diarrhea and there is usually a redness or nappy rash around the anus and the genitals.

Anaphylactic shock

If a person experiences anaphylactic shock (the most severe allergic reaction), symptoms will typically include:

• Difficulty in breathing due to narrowing of the airways and swelling of the larynx
• Rapid heart rate
• Rapid fall in blood pressure causing dizziness or light headedness and cold, clammy skin.
• Itchy urticaria and angioedema
• Severe apprehension or anxiety
• Unconsciousness