Symptoms of Food Allergies

Food allergy symptoms vary and can range from mild to severe. An allergic reaction to food usually develops within minutes to 1 hour and can last hours, days, or even longer.

Common food allergy symptoms include the following:

  • Changes in behavior (e.g., irritability)
  • Diarrhea
  • Facial swelling
  • Flushing (sudden feeling of warmth and reddening of the skin)
  • Hives (urticaria)
  • Itching (often involving the lips, tongue, mouth, throat, nose, and eyes)
  • Nasal congestion (i.e., stuffy, runny nose)
  • Nausea and vomiting
  • Rash (itching and redness of the skin)
  • Stomach pain
  • Wheezing

Severe food allergies also can affect the cardiovascular system and cause abnormal heart rate, chest pain, and very low blood pressure (hypotension). Anaphylaxis, also called anaphylactic shock and allergic cascade, is a life-threatening allergic reaction that requires immediate medical attention.

Signs of anaphylaxis include the following:

  • Convulsions
  • Cyanosis (bluish coloration of the skin)
  • Extremely low blood pressure (hypotension)
  • Pallor (pale, cool skin)
  • Rapid heart rate (tachycardia)
  • Respiratory distress (inability to breathe)
  • Swelling (which can obstruct breathing)
  • Widespread rash

People who have a severe food allergy can experience an allergic reaction from consuming even a trace amount of the food allergen or from being exposed to airborne food allergens. For example, allergens can be released into the air during cooking (e.g., steaming lobster) or when a nut shell is cracked open.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 20 Oct 2008

Last Modified: 13 Oct 2011