Food Allergy



A food allergy is when the body mistakes a food as being harmful. This makes the immune system release chemicals into the blood that cause symptoms to happen. Common food allergens are:

  • Cow's milk
  • Eggs
  • Peanuts
  • Wheat
  • Soy
  • Fish and shellfish
  • Tree nuts such as walnuts and pecans
  • Sesame seeds

Risk Factors

A food allergy often starts when a person is a child. It may also start or continue when a person is an adult. Things that may raise the risk are:

  • Other allergies, such as eczema or hay fever
  • Family history of food allergies



Symptoms may be:

  • An itchy skin rash
  • Swelling of the lips, mouth, or throat
  • Coughing or wheezing
  • Shortness of breath
  • Belly cramps
  • Loose stools (poop)
  • Vomiting
Splotchy body rash -adult
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The doctor will ask about symptoms and past health. A physical exam will be done. The allergy can be confirmed with a:

  • Skin prick test—to look for a skin reaction when exposed to a food
  • Blood test—to look for an antibody when a person is exposed to a food
  • Food challenge—to watch for a reaction to the food after eating it, with medical staff present

People with food allergies may see a doctor who treats allergies.



People with severe food reactions may need medical care right away. Medicine will be given to help quickly open airways.

A food allergy can be managed. Options are:

Avoid the Food

The best way to manage this allergy is to avoid the allergen. Other foods that may have been around the allergen can also cause problems. Education about the allergen and food labels can be helpful.


Medicine can help to manage minor symptoms like itching. Avoidance is the most important step. Medicine should only be used if an allergen was eaten by accident. Minor symptoms can be managed with:

  • Antihistamines to decrease swelling and itching
  • Corticosteroids to treat severe swelling and itching

An epi pen is needed for those who have had severe reactions. It will deliver the medicine epinephrine. It can quickly open airways and ease swelling. It needs to be nearby at all times.


There is no known way to prevent food allergies. Parents should talk to their child's doctor about when to start foods that are often allergens, such as peanuts.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.