Diseases & Conditions

Egg allergy

Eggs are one of the most common allergy-causing foods. Although egg allergy can affect adults, it's more common in children. Most children outgrow their egg allergy by the time they're 5 years old.

Allergic reactions usually occur a few minutes to a few hours after eating eggs or foods containing eggs. Signs and symptoms range from mild to severe and can include skin rashes, hives, vomiting or inflamed nasal passages. Rarely, egg allergy can cause anaphylaxis — a severe, life-threatening reaction.

The key to preventing an allergic reaction if you or your child has an egg allergy is to know what you're eating — so you can avoid eggs and foods that contain eggs. This can be a challenge, as eggs or egg products are a common food ingredient. If a mild allergic reaction occurs, over-the-counter antihistamine medications may help relieve symptoms. Anaphylaxis requires a shot of epinephrine and emergency medical treatment.

All food allergies are caused by an immune system malfunction. Your immune system identifies certain egg proteins as harmful, triggering the production of immunoglobulin E (IgE) antibodies to neutralize the protein (allergen). The next time you come in contact with these proteins, these IgE antibodies recognize them and signal your immune system to release histamine and other chemicals. Histamine and other body chemicals cause a range of allergic signs and symptoms. Histamine is partly responsible for most allergic responses, including runny nose, itchy eyes, dry throat, rashes, hives, nausea, diarrhea, labored breathing and anaphylactic shock.

Both egg yolks and egg whites contain a number of proteins that can cause allergies, but allergy to egg white is more common. Some breast-fed infants have an allergic reaction to egg proteins in breast milk.

To evaluate whether you or your child has an egg allergy, your doctor may:

• Ask detailed questions about signs and symptoms
• Perform a physical exam
• Have you keep a detailed diary of the foods you or your child eats
• Have you eliminate eggs from your diet or your child's diet (elimination diet) — and then have you eat the food in question again to see if it causes a reaction

Your doctor may also recommend one or both of the following tests:

• Skin test. In this test, your skin is pricked and exposed to small amounts of the proteins found in eggs. If you're allergic, you develop a raised bump (hive) at the test location on your skin. Allergy specialists usually are best equipped to perform and interpret allergy skin tests.
• Blood test. A blood test can measure your immune system's response to eggs by measuring the amount of certain antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample can be tested in a medical laboratory, where it can be tested for evidence of sensitivity to eggs.

If your doctor suspects your problems are caused by something other than a food allergy, you may need other tests to identify — or rule out — other medical problems.

The only way to prevent an allergic reaction is to avoid eggs or egg products altogether. This can be difficult, as the egg is a common food ingredient. Despite your best efforts, you or your child may still come into contact with eggs. Medications, such as antihistamines, may reduce signs and symptoms of an egg allergy. These drugs can be taken after exposure to eggs to control an allergic reaction and help relieve discomfort.

If you or your child has a serious allergic reaction (anaphylaxis), you may need an emergency injection of epinephrine (adrenaline) and a trip to the emergency room. If you're at risk of having a severe reaction, you or your child may need to carry injectable epinephrine (EpiPen) at all times.