Allergy Types: Food Allergies: Egg Allergy
Egg allergy is a type of food allergy. It is a hypersensitivity to dietary substances from the yolk or whites of eggs, causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people around the world.
Egg allergy appears mainly, but not exclusively, in children. In fact, it is the second most common food allergy in children. (The most common is cows’ milk allergy.) It is usually treated with an exclusion diet and vigilant avoidance of foods that may be contaminated with egg. The most severe food allergy reaction is called anaphylaxis and is an emergency situation requiring immediate attention and treatment with epinephrine. The Asthma and Allergy Foundation of America estimates that most children outgrow egg allergy by the age of five, but some people remain allergic for a lifetime.
Egg white intolerance
Egg whites, which are potent histamine liberators, also provoke a nonallergic response in some people. In this situation, proteins in egg white directly trigger the release of histamine from mast cells on contact. Because this mechanism is classified as a pharmacological reaction, or “pseudoallergy”, the condition is considered a food intolerance instead of a true IgE-based allergic reaction.
The response is usually localized, typically in the gastrointestinal tract. Symptoms may include abdominal pain, diarrhea, or any symptoms of histamine release. If sufficiently strong, it can result in an anaphylactoid reaction, which is clinically indistinguishable from true anaphylaxis.
Some people with this condition tolerate small quantities of egg whites. They are more often able to tolerate well-cooked eggs, such as found in cake or dried egg-based pasta, than loosely cooked eggs, such as fried eggs or meringues, or uncooked eggs.
An immune system overreaction causes food allergies. For egg allergy, the immune system mistakenly identifies certain egg proteins as harmful. When you or your child comes in contact with egg proteins, immune system cells (antibodies) recognize them and signal the immune system to release histamine and other chemicals that cause allergic signs and symptoms.
Both egg yolks and egg whites contain proteins that can cause allergies, but allergy to egg whites is most common. It’s possible for breast-fed infants to have an allergic reaction to egg proteins in breast milk if the mother consumes eggs.
Certain factors can increase the risk of developing an egg allergy:
- Atopic dermatitis. Children with this type of skin reaction are much more likely to develop a food allergy than are children who don’t have skin problems.
- Family history. You’re at increased risk of a food allergy if one or both of your parents have asthma, food allergy or another type of allergy — such as hay fever, hives or eczema.
- Age. Egg allergy is most common in children. With age, the digestive system matures and allergic food reactions are less likely to occur.
If your doctor thinks your child might have an egg allergy, he or she will probably refer you to an allergist or allergy specialist for further testing. The allergy specialist will ask things like how often your child has the reaction, the time between eating the food and the start of symptoms, and whether any other family members have allergies or conditions like eczema and asthma.
The allergy specialist may do a skin test. This involves placing liquid extracts of egg protein on a child’s forearm or back, pricking the skin a tiny bit, and waiting to see if a reddish, raised spot forms, indicating an allergic reaction.
Your child will need to stop taking anti-allergy medicines (such as over-the-counter antihistamines) 5 to 7 days before the skin test because they can affect the results. Most cold medicines and some antidepressants also may affect skin testing. Check with the allergist’s office if you’re unsure about what medicines need to be stopped and for how long.
The doctor also might take a blood sample and send it to a lab, where it will be mixed with some of the suspected allergen and checked for IgE antibodies.
In some cases, positive results of skin and blood tests aren’t enough to prove that symptoms are being caused by eggs. So doctors may use what’s called a food challenge to help diagnose the allergy. In a food challenge, the child will eat foods that contain eggs while being very closely watched by the doctor. If symptoms appear after eating egg products, it’s likely the child has an egg allergy.
The only way to prevent egg allergy symptoms is to avoid eggs or egg products. Some people with egg allergies, however, can tolerate foods that contain well-cooked eggs, such as baked goods.
Antihistamines to ease symptoms
Medications such as antihistamines may reduce signs and symptoms of a mild egg allergy. These drugs can be taken after exposure to eggs. They aren’t effective for preventing an allergic egg reaction or for treating a severe reaction.
Emergency epinephrine shots
You may need to carry an emergency epinephrine injector (EpiPen, Auvi-Q, others) at all times. Anaphylaxis requires an epinephrine shot, a trip to the emergency room and observation for a time to be sure symptoms don’t return.
Learn how to use the autoinjector. If your child has one, make sure caregivers have access to it and know how to use it. If your child is old enough, make sure he or she understands how to use it. Replace the autoinjector before its expiration date.
Most children eventually outgrow egg allergy. Talk to your child’s doctor about frequency of testing to see whether eggs still cause symptoms. It may be unsafe for you to test your child’s reaction to eggs at home, particularly if your child has had a severe reaction to eggs in the past.
Promising New Treatment for Kids With Egg Allergy
If you’re allergic to eggs, a doctor has probably told you to avoid the protein. But researchers have now found that eating small amounts of egg for several months may lower the allergic reaction.
The multi-center study, published in the New England Journal of Medicine, found that giving children with egg allergies a small amount of egg-white powder for 10 months reduced or eliminated their allergy after the study period.
About 4 percent of children in the U.S. experience food allergies, according to the research, and egg allergy is one of the most common. Many children outgrow the allergy after age 5, but for some, the sensitivity can continue into adulthood. Food allergy reactions can range from a mild rash to death.
“The children were treated and then taken off treatment, the first large study to do so. Almost a third of those treated were able to come off treatment and now eat eggs in their diet,” Dr. Wesley Burks, the lead author of the study and chairman of pediatrics at UNC, told ABCNews.com.
Researchers enrolled 55 children and teens with egg allergies. Participants’ families were then either given the equivalent of one-third of an egg in powder form, or a placebo, to mix into their children’s food.
After 10 months, researchers gave the kids an “oral food challenge” in which they were given 5 grams of egg powder, the equivalent to one whole egg. They found that 55 percent of the children did not have an allergic reaction at that time. After 22 months, researchers gave the children two whole eggs and found that 75 percent of the children were no longer allergic.
More than one-quarter of the study group was able to work egg back into their regular diet regimen.
The approach has been taken with peanut allergies, as well as milk and egg in the past. This suggests it could be applicable to all food allergies, said Dr. Harold Nelson, a professor of medicine at National Jewish Hospital in Denver.
But Burks warned parents not to try this at home. More trials are needed before the allergy intervention is used in widespread clinical practice. There needs to be Food and Drug Administration approval and further trials with bigger patient populations, and it could take a number of years before the intervention is seen in general practice.
“It is likely that this will eventually become an accepted clinical approach but even then should be only done by physicians with experience in the procedure, who appreciate the dangers and have the time to carefully supervise the process,” said Nelson. “This will never be an approach that should be conducted out in primary care.”
“This study is important and relevant because it adds to growing evidence that oral immunotherapy is an effective way that we can treat food allergies,” said Dr. Neeta Ogden, a New Jersey allergist in private practice. “The results are incredibly promising as a potential cure for some children with food allergies.
In the past, avoidance and elimination has been the only option, which is very limiting for these patients’ diets, said Ogden.
“Also, the threat of accidental exposure or ingestion of allergenic foods — a common cause of allergic reactions and anaphylaxis in food allergic children is markedly diminished,” she said.
Fifteen percent of food allergic individuals experience an accidental ingestion per year, said Dr. Tania Mucci, an allergist at Winthrop University Hospital in New York. While egg allergic patients would still need to be diligent, the potential for oral egg immunotherapy to decrease the risk of a severe reaction from an accidental ingestion would be extremely valuable for the patients mental and of course, physical health.
“Oral immunotherapy for food allergy, if safe and standardized, would be the Holy Grail for food allergic patients,” said Mucci. “Immunotherapy to grasses, trees, cat, and dog is curative in 75 percent of patients. At this point in time, all we have to offer for food allergic patients are strategies for avoidance.”
Here are some things you can do to avoid an allergic reaction, and to keep it from getting worse if one does occur.
- Read food labels carefully. Some people react to foods with only trace amounts of egg.
- Be cautious when eating out. Your server or even the cook may not be completely certain about whether a food contains egg proteins.
- Wear an allergy bracelet or necklace. This can be especially important if you or your child has a severe reaction and can’t tell caregivers or others what’s going on.
- Let your child’s caregivers know about an egg allergy. Talk to your child’s babysitters, teachers, relatives or other caregivers about the egg allergy so that they don’t accidently give your child egg-containing products. Make sure they understand what to do in an emergency.
- If you’re breast-feeding, avoid eggs. If your child has an egg allergy, he or she may react to proteins passed through your milk.
Hidden sources of egg products
Unfortunately, even if a food is labeled egg-free it may still contain some egg proteins. When in doubt, contact the manufacturer.
Foods that contain eggs can include:
- Baked goods
- Breaded foods
- Processed meat, meatloaf and meatballs
- Puddings and custards
- Salad dressing
- Many pastas
- Foam on alcoholic, specialty coffees
Several terms indicate that egg products have been used in manufacturing processed foods, including:
- Words starting with “ova” or “ovo,” such as ovalbumin or ovoglobulin
Another potential source of exposure is cross-contamination in home-prepared dishes or meals, especially when you’re eating in other people’s homes where they may not be aware of the risk.
Vaccinations and egg allergy
Some shots to prevent illness (vaccines) contain egg proteins. In some people, these vaccines pose a risk of triggering an allergic reaction.
- Measles-mumps-rubella (MMR) vaccines are generally safe for children with egg allergy, even though eggs are used to produce them.
- Flu (influenza) vaccines sometimes contain small amounts of egg proteins. However, a flu vaccine that doesn’t contain these proteins is approved for use in adults age 18 and older. And even vaccines that do have egg proteins can be given safely to most people with egg allergy without any problems. If you or your child has had a reaction to eggs in the past, talk to your doctor before getting a flu vaccination.
- Yellow fever vaccine can provoke an allergic reaction in some people who have egg allergy. It’s given to travelers entering countries where there’s a risk of contracting yellow fever. It’s not generally recommended for people with egg allergy, but is sometimes given under medical supervision after testing for a reaction.
- Other vaccines are generally not risky for people who have egg allergy. But ask your doctor, just to be safe. If your doctor is concerned about a vaccine, he or she may test you or your child to see whether it is likely to cause a reaction.
The best way to be sure a food is egg free is to read the label. Manufacturers of foods sold in the United States must list on their labels whether a food contains any of the most common allergens. This means that you should be able to find statements like these somewhere on the label: “contains egg ingredients,” “made using egg ingredients,” or “made in a facility that also processes eggs.”
Still, to make sure the foods you eat are egg free, it helps to look at the label for any ingredients that might come from eggs. That also means asking questions when eating out at restaurants or at a friend’s home.
The word “egg” is easy to spot on an ingredients list — anytime you see words like “egg solids” or “dried egg,” you’ll know to avoid that food. But sometimes food labels aren’t so clear. Here’s how eggs might show up on an ingredients list:
- silici albuminate
When you eat in a restaurant or at a friend’s house, try to find out how foods are cooked and what’s in them. In some cases, you may want to bring your own food with you. When you’re shopping, look for egg-free alternatives to foods like pasta that usually contain eggs.
People with an egg allergy may find that the health food section of the grocery store offers the most options. That’s where you’ll find vegan foods that are made without eggs or egg products.
When preparing your own food, you can substitute one of these egg alternatives in your recipes. Each of these replaces one egg (these substitutes may not work as well in recipes that call for more than three eggs):
- 1 teaspoon baking powder + 1 tablespoon liquid + 1 tablespoon vinegar
- 1 teaspoon yeast dissolved in ¼ cup warm water
- 1½ tablespoons water + 1½ tablespoons oil + 1 teaspoon baking powder
- 1 packet gelatin + 2 tablespoons warm water (don’t mix until ready to use)
- 1 tablespoon pureed fruit such as apricots or bananas
- 1 tablespoon ground flaxseed + 3 tablespoons water
When cooking at home, always scrub the utensils you’re using in case they have been used on egg products.
Although the number of people in the United States with food allergies is low (just over 1% of the total population), there’s a growing awareness about food allergies. This means that everyone — from the waitstaff at a restaurant to food manufacturers — is more understanding and willing to accommodate a person’s food needs.
So living with an egg allergy doesn’t have to be a big pain, just a bit of an adjustment.
In a study presented at the 2007 American Academy of Allergy, Asthma, and Immunology (AAAAI) meeting, 50% of patients outgrew egg allergy by age 17. Of those patients who outgrew it, 45% did so by age 5. Children who outgrew the allergy tended to have peak IgE levels at around age one, which then decline.
The most significant complication of egg allergy is having a severe allergic reaction requiring an epinephrine injection and emergency treatment.
The same immune system reaction that causes egg allergy can also cause other conditions. If you or your child has an egg allergy, you or your child may be at increased risk of:
- Allergies to other foods, such as milk, soy or peanuts
- Allergies to pet dander, dust mites or grass pollen
- Allergic skin reactions such as atopic dermatitis
- Asthma, which in turn increases the risk of having a severe allergic reaction to eggs or other foods