Egg Allergy or Egg Intolerance: Symptoms & Treatment
Both egg intolerance and egg allergy can cause digestive symptoms, but they are not the same. If you have egg allergy, you must avoid eggs completely. If you have egg intolerance, you may be able to tolerate a small amount of eggs.
Egg allergy affects about two percent of children. About 70 percent of children outgrow this allergy by age 16.  Egg allergy is one of the most common food allergies along with milk, peanuts, and shellfish. If you have an egg allergy, there is always a danger that even a small amount of egg protein can cause a life-threatening reaction, called anaphylaxis. [1-3]
Food sensitivities, like egg intolerance, are more common than food allergies and many adults have an egg intolerance. If you have egg intolerance, you may be able to tolerate a small amount of egg, but you may experience symptoms if you eat too much of it. Unlike a severe allergic reaction, an intolerance reaction is not life-threatening and mainly just uncomfortable. [2,3]
Egg Allergy vs Egg Intolerance Symptoms
According to the American Academy of Allergy, Asthma, and Immunology, within a short time of eating an egg or sometimes even touching an egg and then touching your mouth, you may have these egg allergy symptoms: 
- Skin swelling, rash, or hives
- Runny nose and sneezing
- Red and watery eyes
- Stomach ache, nausea, vomiting, or diarrhea
A severe reaction – anaphylaxis – can cause a sudden drop in blood pressure, swelling in the throat that blocks breathing, and if untreated, can lead to loss of consciousness and may even be fatal. [1-3]
Symptoms of egg intolerance, or other food intolerances, can cause the same digestive symptoms as egg allergy, but none of the other egg allergy symptoms. It does not cause anaphylaxis. Egg intolerance symptoms may also cause heartburn or headache, symptoms that are not common with a food allergy. 
What Causes Egg Allergy or Egg Intolerance?
An egg allergy, like other food allergies, is caused when a food protein is recognized as a foreign invader by your body’s defense system, your immune system. Food allergies may be caused by genes passed down through families. If you have an egg allergy, your immune system makes antibodies to egg protein. If any egg protein – which is mainly in egg yolk – is detected, antibodies launch an attack by releasing chemicals, like histamine, that cause inflammation. [1,3]
Food intolerances are often caused by lack of an enzyme needed to break down a food protein. That can make it harder to digest the food and may cause irritation in your digestive tract. Intolerance does not cause inflammation that occurs with an allergy. [2,3] People with irritable bowel syndrome may be more likely to have food intolerance.  The most common food intolerance is milk, which is caused by not having enough of the enzyme needed to break down the milk protein lactose. [2,3]
Diagnosis and Treatment of Egg Allergy and Egg Intolerance
The best way to diagnose egg allergy is with skin tests or blood tests to look for antibodies to egg proteins. The only treatment is to completely avoid eggs. Although most of the proteins are in the yolk, there are enough proteins in egg white to cause a reaction. Egg protein is in lots of foods; therefore, egg is one of the nine food allergies that packaged foods must include on their ingredient labels. If you have an egg allergy reaction, antihistamines may help. A severe reaction may require an injection of epinephrine. People who are at risk of anaphylaxis from egg allergy may need to carry an epinephrine auto injector. 
Because egg intolerance does not cause an immune system reaction, there are no skin or blood tests that can diagnose it. Food intolerance is diagnosed only by your history. Your health care provider may ask you to keep a food diary to help link your symptoms to the foods you eat. Treatment of egg intolerance is avoidance, but unlike egg allergy, you probably do not need to avoid tiny amounts of egg in other foods. If you have a reaction, over-the-counter medicines for headache, heartburn, or other symptoms is the best treatment. [2,3]
Egg Allergy, Egg Intolerance, and Vaccines
If you have egg intolerance, you don’t need to worry about egg protein in any vaccine, because the amount is so small. If you have egg allergy, you don’t need to worry about egg protein in the flu shot because egg protein has been removed. The CDC says that anyone with egg allergy can safely take the flu vaccine. One vaccine that still contains egg protein is yellow fever. Both the CDC and the World Health Organization say people with an egg allergy should not get it. You don’t need this vaccine unless you live or travel in South America or Africa. 
An egg intolerance might require you to change the way you eat, but does not have as serious of symptoms as an egg allergy.
© Piotr Adamowicz | Dreamstime.com