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Most people are born with systems to help them adapt to the threats of the outside world, including the immune system. But for some, these systems get a little too helpful, and end up causing problems like allergies.
What causes allergies?
Allergies are outsized reactions to a foreign but non-harmful external substance.
Your immune system is designed to attack and destroy substances it perceives as a threat. When it’s first exposed to such a substance, your immune system will generate antibodies that bind to the substance and trigger an immune response against it.
One class of these antibodies is called immunoglobulin E, or IgE. IgE specializes in activating cells that release the chemical signals that cause itching, swelling and other symptoms. In short: IgE activation can cause an allergic reaction.
Take pollen, for example: Allergies occur when your immune system incorrectly perceives pollen as a threat and starts producing IgE against it. When this happens, you’ve become allergic to pollen. The next time your body encounters the allergen, IgE recognizes it as a threat and triggers an immune response again, causing you to sneeze — or worse.
Allergic reactions are fairly common. Many children have allergies: According to the Centers for Disease Control and Prevention (CDC), one in five children has seasonal allergies, over 10% have eczema (yes, eczema is an allergic condition), and just over 5% have a food allergy.
Not everyone who has an allergy will have it forever, though.
Why do kids grow out of allergies?
Many times, kids grow out of their allergies. So, what’s going on here? Why might your body decide that a foreign object is no longer dangerous?
In short, the causes behind allergy development and cessation are still very much up for debate. But research on the topic is starting to grow.
“Some children spontaneously outgrow their allergies, and it is not known why,” says Dr. Dilawar Khokhar a specialist in pediatric allergies and immunology at UW Medicine. Others respond to treatments like desensitization (allergy shots) or immune modifying medications.
Outgrowing allergies seems to mostly depend on which type of allergy you have and how severe it is.
"Most children will outgrow a milk or egg allergy,” Khokhar says, noting that this can still take years. On the flip side, most children do not outgrow peanut or tree nut allergies.
Researchers know that this has something to do with the body producing fewer IgE antibodies over time, especially in relation to certain allergies. If your allergies are less severe at the start, this could be due to a number of changes to your body’s immune system, including a decrease in IgE.
That said, there’s still much research to be done about why IgE starts to reduce for certain allergies in the first place.
Why do adults develop new allergies?
Adults will sometimes develop allergies at later ages, too. Again, Khokhar says it’s all about the type of allergy.
For example, many adults got pets for the first time during the pandemic he points out. Many of these people subsequently developed new pet dander allergies because of these new exposures.
Khokhar also says drug allergies are more common in adults because they tend to take more medications than children do.
And in some cases, adults can develop new allergies seemingly out of the blue — although there are a few theories about why this happens, likely an interaction between genetics and environmental factors.
It’s also believed that other experiences such as pregnancy or relocating to a new environment with different allergens can also trigger an immune response that causes someone to develop new allergies.
What’s next for allergy treatments?
Avoidance is a good place to start: Avoid foods you might be allergic to, and make sure your environment is clear of things like dust, which could exacerbate your reaction. Over-the-counter antihistamines can be used to treat mild allergic reactions, as can nasal steroids. If you have a severe reaction (like throat swelling, facial swelling, body-wide hives or a rash, or dizziness), you should go to a hospital right away.
EpiPens can be used to protect against life-threatening allergic reactions in-the-moment, too; you can carry them with you just in case, as a protective measure. A doctor will be able to give you a prescription for one if they deem it necessary. Some people may also need other prescription medications, like leukotriene modifiers.
If you notice hives or digestive issues after eating a certain food, you might want to book an appointment with an allergist or an immunologist. Allergists can determine the best diagnostic tests and treatment plan for you based on your symptoms.
Then you get to your newer immunotherapies in which you’re repeatedly exposed to the allergen considered responsible for your allergies to induce tolerance. The two most common forms of immunotherapy are subcutaneous immunotherapy (SCIT), aka “allergy shots” and the newer form: sublingual (SLIT).
Newer immunotherapies expose you to an allergen repeatedly to induce tolerance. Dr. Jing Yi “Jenny” Sun, another pediatric allergy and immunology specialist at UW Medicine, recommends allergy shots.
“Allergy shots for environmental allergies serve to retrain the immune system to tolerate things that patients are previously allergic to,” she says.
Sun also recommends sublingual immunotherapy, or SLIT, which is delivered under the tongue instead of via an injection. These immunology treatments can be formulated specifically for each patient by using the results of a standard allergy test. They have the benefit of being less invasive, but with the same effectiveness as allergy shots.
The bottom line: Allergies are common and there are many ways to treat them, with more coming down the pike. Talk to an allergist about the options available to you.
