What is Egg Allergy?
The immune system’s main job is to differentiate between what is part of the body (“self”) and what is foreign (“not-self”). By doing this, it fights off harmful invaders before they can cause serious illnesses. Hence, a strong immune system is key to staying healthy. Sometimes, the immune system doesn’t work as well as it should due to inherent flaws or medications (like steroids or cancer drugs). In some situations, the immune system can fail to distinguish between “self” and “not-self,” leading to the production of auto-antibodies that attack the body’s cells.
Food allergy falls in this latter category. This is not because the immune system is faulty (as in an immunodeficiency) or because it attacks the body’s own cells (as in autoimmune disorders). Instead, in a food allergy, the immune system produces antibodies against elements from food (hence, “not-self”). One example is egg allergy, a condition where the immune system produces an unfavorable response to substances found in egg whites or yolks. After milk allergy, this is the second most common food allergy in the U.S.
Mast cells and basophils, which are a specific type of white blood cell, play a significant role in egg allergy. These cells, including similar ones like eosinophils and neutrophils, contain small particles with compounds that trigger local inflammation. These include heparin, histamine, leukotrienes, and chemotactic factors. The release of histamine and leukotrienes leads to muscle contraction, while histamine also promotes increased permeability of blood vessels. Chemotactic factors attract more white blood cells to the area. Despite their similarities, mast cells and basophils are considered different because they originate from different lineages in blood cell formation and are found in different areas in the body.
What Causes Egg Allergy?
An egg allergy is a reaction by the body’s immune system, specifically a response by a type of antibody called IgE. If you’re healthy but exposed to egg allergens (substances that trigger an immune response), your body can produce specific IgE antibodies against them. There’s a possibility that egg allergies may be linked to your genetics. This means if your parents or other close family members have allergies, you might be more likely to develop an egg allergy yourself.
Experts generally agree that our body’s responses involving IgE antibodies are influenced by certain genes that are linked together on chromosome six. These genes are part of our body’s system for identifying and reacting to foreign substances that it doesn’t recognize as its own.
Other elements that might be associated with the development of allergies include the IgE Fc receptor. This receptor, found on chromosome eleven, can bind to the IgE antibodies, and this process can trigger an allergic reaction.
Risk Factors and Frequency for Egg Allergy
Figuring out how many people have food allergies can be quite tricky. It’s especially challenging to identify true egg allergy due to several factors. For one, some people might not be diagnosed correctly because they haven’t undergone the necessary tests. These tests can include skin tests for allergens, blood tests for specific allergy-related substances in the egg, or food challenges.
Secondly, people who do have an egg allergy might not realize they have it, especially if they don’t eat eggs often. Lastly, some people might think they have an egg allergy because they experience symptoms after eating eggs, but the actual cause could be a different allergen or a non-allergy reason like asthma or stomach troubles.
Yet another complication is telling the difference between an actual egg allergy and simple egg intolerance. These two conditions can look alike, but an allergy involves a specific response from your immune system. If this distinction isn’t made clear, there could be a lot of mistaken diagnoses.
- Hen egg allergies typically show up within a year of birth and can affect both sexes equally.
- Many people grow out of their egg allergy by the time they’re in school, although some may only outgrow it in their teenage years.
- Unlike some other types of food allergies, egg allergies usually get better or go away entirely as the person gets older.
Signs and Symptoms of Egg Allergy
An allergy to hen eggs often arises during infancy and primarily shows up as skin reactions, such as widespread hives and swelling. However, the allergy can also cause vomiting or breathing problems. Typically, these symptoms can be seen within minutes after consuming eggs, however, they may also take up to 2 hours to appear. Serious cases could involve a dangerous allergic reaction called anaphylaxis, which would require epinephrine – commonly known as an adrenaline injection.
The egg allergy could also result in two related disorders: eosinophilic esophagitis and food protein-induced enterocolitis syndrome (FPIES). Eosinophilic esophagitis is an inflammation-related illness that stems from a buildup of certain white blood cells, called eosinophils, in the body. This condition is caused by both IgE and non-IgE processes. Egg proteins are known to be a common triggering factor for this condition. Much like other forms of esophagitis, eosinophilic esophagitis can cause difficulty swallowing and other non-specific symptoms like chest discomfort.
FPIES, an inflammatory disorder, usually presents with symptoms like vomiting, tiredness, and diarrhea, 2 to 6 hours after consuming egg proteins.
Additionally, an allergic reaction to egg protein may appear as a skin condition called dermatitis, typically in children under one. However, if dermatitis occurs after one year of age, egg allergy is typically not the cause, and other possible explanations should be explored.
Finally, asthma has been found to often coincide with food allergies due to its association with IgE triggered reactions. A study involving 1218 children reported that around 80% of the children allergic to eggs also had asthma.
Testing for Egg Allergy
If you suspect that you might be allergic to eggs, your doctor will conduct a detailed examination which involves taking information of your diet, specifically your egg intake, and the nature and timing of any reactions you might have experienced after eating eggs or products containing eggs. Information about similar allergies in your family members could also be helpful in understanding your condition.
To diagnose an egg allergy, your doctor may conduct a skin test, where a small quantity of egg protein is introduced beneath your skin and a possible allergic reaction is observed. Alternatively, your doctor could order a blood test to measure your levels of egg-specific Immunoglobulin E (IgE), an antibody that your body might produce in response to an egg allergy. Another diagnostic test is the oral food challenge, where you would eat a food containing eggs under medical supervision to see if an allergic reaction occurs. While keeping a food diary, where you note down everything you eat, cannot definitively diagnose an egg allergy, it can be helpful in identifying if eggs might be causing your symptoms.
Oral food challenges, especially the double-blinded, placebo-controlled ones (where neither you nor the medical professional knows if what you are eating contains egg protein), are considered the most reliable method for diagnosing egg allergies. However, this should always be done under the supervision of a medical professional due to the risk of a severe allergic reaction, known as anaphylaxis.
When checking for egg allergies, skin tests may not always be completely reliable as they can sometimes give false negative results which may be due to recent use of antihistamine medications or if the person recently had a severe allergic reaction.
Another kind of test, called immunoassays, which can involve tests such as radioallergosorbent tests (RASTs) or fluorescent enzyme immunoassay (FEIA), could also be performed. These are less prone to human mistake but aren’t as sensitive as skin tests, however they are not affected by prior use of antihistamine medications.
Oral food challenges are quite comprehensive but need to be done under the correct conditions for accurate results. Thus, all antihistamines and certain other medications need to be stopped before undergoing an oral food challenge. If eggs are not a part of your daily diet and can be easily avoided, or an egg allergy is strongly suspected due to your medical history and high egg-IgE levels, it might not be necessary to perform this test.
Treatment Options for Egg Allergy
One common approach to dealing with egg allergies is to avoid contact with eggs as much as possible. However, this approach may not provide a permanent solution and might not always be practical. In fact, the effort required to avoid eggs can lead to stress for both the child with the allergy and their parents. The increased focus on avoiding eggs often takes away from other aspects of the child’s daily life.
“Egg-free” food items, which parents may need to buy to avoid an allergic reaction, can be more expensive than regular ones that contain eggs. For children, avoiding eggs could also impact their social experiences and could possibly make them feel isolated from their friends.
In addition, avoiding eggs can put children at a higher risk of not getting enough important nutrients. For example, a study observed that children under two years old who were not allowed to consume certain foods, including eggs, had lower body mass indexes compared to children of the same age who did not have any dietary restrictions.
Oral immunotherapy (OIT) is another approach to managing egg allergies. This involves consuming small, increasing amounts of egg proteins to help the body get used to them. While OIT has been successful in helping patients become less sensitive to eggs, it’s a relatively long process and often needs to be continued for a long time.
What else can Egg Allergy be?
It’s not always straightforward to identify an egg allergy, because the symptoms are quite general and can be mistaken for other common issues like food intolerance, problems with the digestive system, or an allergy to a different type of food.
For example, someone who is intolerant to lactose (a sugar found in milk) might eat something that has both dairy and egg in it, like custard or ice cream. They might then experience problems with their digestive system, but these are caused by the lactose, not an egg allergy. This can make it seem like they’re allergic to eggs, even though the reaction isn’t triggered by a specific allergy-related antibody called IgE.
On top of that, skin conditions like atopic dermatitis can sometimes occur due to contact allergies, which can further complicate matters.
What to expect with Egg Allergy
Most children with hen egg allergies outgrow them by the time they start school. However, some children may not outgrow them until they become teenagers. Several factors can influence when a child might outgrow their egg allergy. These include how much egg-specific IgE (a type of protein that the immune system makes in response to an allergen) a child has, the age at which they are diagnosed, how severe their symptoms are, their skin test reaction size, and whether they can tolerate eggs in well-cooked forms.
Measurements of egg-specific serum protein IgE to IgG4 ratios (types of proteins our immune system produces in response to allergens) could be useful in predicting when a child might outgrow an egg allergy, even if this method isn’t used often. A study in 2013 showed that a skin-test reaction size of about 5mm aligned with a 95% probability of having an egg allergy.
Furthermore, a review of multiple studies highlighted the usefulness of doing skin allergen tests before oral food challenges. Even though the correlation between skin-test reaction size and the likelihood of having an egg allergy isn’t perfect, it could potentially save children from having to go through the more time-consuming and potentially uncomfortable process of oral food challenges.
Possible Complications When Diagnosed with Egg Allergy
If someone is allergic to eggs, they can experience a range of symptoms. This can include skin issues like rashes or hives, stomach problems like diarrhea, nausea, and vomiting, or even a severe allergic reaction called anaphylaxis, which can be life-threatening.
Common Egg Allergy Symptoms:
- Rashes
- Hives
- Diarrhea
- Nausea
- Vomiting
- Anaphylaxis (potentially life-threatening)
Preventing Egg Allergy
If your baby or small child is allergic to eggs, it’s crucial for you, as parents or primary caregivers, to understand how to manage this allergy. A key part of this is not giving your child food that contains eggs, and being careful to check all food for traces of egg.
If your child has a severe egg allergy, they could be at high risk of a serious allergic reaction known as anaphylaxis. If this is the case, their doctor might give them a prescription for a medicine called epinephrine, and teach you how to use it. Epinephrine is the best treatment for anaphylaxis. It works by calming the muscles in the body and reducing the severity of the reaction.
It’s really important for you to know that medicines like Benadryl or other anti-histamines are not replacements for epinephrine. Even if these medicines might seem to help with allergic reactions, they are not suitable for treating serious reactions like anaphylaxis.
