Editor's note: This popular story from the Daily Briefing's archives was republished on March 28, 2019.

Slate's Brian Palmer ponders the "real midlife crisis": Allergy symptoms that lay dormant for decades before returning in a person's 30s, only to diminish around retirement age.

Allergy experts have a basic understanding of how allergies work: Sufferers produce the antibody Immunoglobulin E (IgE) when exposed to things like cat dander or peanuts, which results in sneezing, sniffling, and red, itchy eyes.

However, experts are less clear on why the condition comes and goes. People tend to experience more severe symptoms from ages five to 16, then get nearly two decades of relief before the condition returns in the 30s, only to have symptoms disappear for good around age 65.

Palmer writes that three types of hypotheses—environmental, infectious, and psychological—attempt to explain the diminution of allergy symptoms in your 20s:

• Environmental: People who develop allergies at a young age are likely to remain in the same environment throughout their childhood. After they leave their parents' homes, however, they may no longer be plagued by allergens. For example, individuals who go to college live in dorms with tile floors, plastic-encased mattresses, and no pets, making them relatively hypoallergenic compared to many homes.
• Infectious: Research has found that immune systems of mice injected with certain viruses become very responsive to IgE. Likewise, experts note that children diagnosed with respiratory or cold viruses develop allergies at a higher rate than those who have not battled an infection. The theory may also explain why parents—who are surrounded by kids who get lots of colds and suffer from allergies—are more prone to allergic episodes.
• Psychological: Although allergies are real, many immunologists believe that state of mind is an important part of how we experience their symptoms. Common distractions for young adults—romance and sports, for example—make allergy symptoms less important.

Meanwhile, the remission of allergy symptoms in the golden years is due to a decline in immune function, which diminishes a person's IgE response to allergens. Other people with weakened immune systems, including women in late pregnancy and people on medications that suppress immunity, may also experience fewer allergy symptoms.

Is there a way to stop allergies from re-emerging in your 30s?

There is little research on how to stave off the re-emergence of allergy symptoms in one's 30s, Palmer writes.

"It appears that the best advice to stave off the return of allergies is either difficult or unpalatable," Palmer writes. On the one hand, "You could live the life of a vagabond, constantly on the run from the substances that trigger your hyperactive immune system," or, "You could forgo children, in hopes of avoiding the midlife surge of infections that kids seem to bring," he suggests.

Realistically, the best solution is to follow standard protocol. "We have drugs to treat allergies," says Mitchell Grayson, an associate professor of allergy and immunology at the Medical College of Wisconsin, adding, "They work pretty well" (Palmer, Slate, 4/14).

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