Why You Suddenly Have Allergies

When Dr. Gailen Marshall was training to become a physician, he was taught that allergies were a kid thing. “Back in the day, the allergist’s office was full of children,” says Marshall, who is the president of the American College of Allergy, Asthma, and Immunology. “If you ever thought about doing allergy testing or allergy shots in someone older than 40, that’s because you were just a money-grubbing doctor.”

A lot has changed since then. In 2021, about a quarter of U.S. adults reported seasonal allergies, compared to 19% of children.

It's become clear, Marshall says, that allergies aren’t only a concern for kids—and that seasonal allergies can change throughout the course of someone’s life.

Allergies can get worse—or even begin—as you age

Allergy symptoms happen when the immune system interprets typically harmless substances, such as grass or pollen, as threats. People without allergies don’t have immune responses to these substances. Those who are sensitive to them, however, produce antibodies to fight them off, kickstarting a process that leads to symptoms like sneezing, runny nose, and itchy eyes.

“If you have the allergic antibody present, we say you’re sensitized,” explains Dr. Lily Pien, an allergy and immunology specialist at the Cleveland Clinic. But it can take a while—even years—for sensitization to build to the point where someone experiences symptoms. When someone reaches that point depends on a mix of factors, including their genetic predisposition, intensity and timing of exposure to allergens, and underlying health conditions, Pien says. That variation helps explain why allergies "can manifest at different times during someone’s life,” she says.

Moving to a different region can also spark adult-onset allergies, says Dr. Rana Misiak, an allergist at Henry Ford Health. “Pollen seasons can be really different from the Midwest to the Southwest to the Northeast,” Misiak says, and adjusting to a new one can lead to issues that were never present previously.

In recent decades, there have also been societal and environmental shifts that contribute to upticks in allergies among people of all ages, Marshall says. The warming climate contributes to longer, more intense allergy seasons; globalization has introduced certain plant species to new areas; and air pollution can exacerbate all sorts of health conditions, he says.

But if you’re suddenly experiencing seasonal allergies for the first time well into adulthood, Pien says it’s worth first ruling out other causes. Bacterial and viral infections can cause allergy-like symptoms, as can anatomical issues like a deviated septum. Some people are also sensitive to irritants like cigarette smoke and perfume, but are not technically allergic to them.

Can you outgrow allergies?

Yes—but it’s not guaranteed. Roughly a quarter to a third of kids outgrow their childhood allergies, Misiak estimates. Unfortunately, though, “it’s much more difficult to lose allergies or outgrow allergies as an adult,” Pien says.

Some people with allergies do see their symptoms improve over time, but it’s not always clear why. Sometimes it’s related to lifestyle shifts, like spending more time indoors and away from pollen, or moving to a new region. Other times, Misiak says, someone may build up a tolerance to their triggers—though she says she sees that most often with pet allergies.

How to prevent and treat allergies

As a first resort, avoid your allergen to the extent possible. But since that's easier said than done with environmental allergens like pollen, Marshall suggests starting allergy medications—like antihistamines or corticosteroids—a week or two before the worst of allergy season for a better chance at preventing symptoms.

Some studies also suggest that seemingly unrelated health factors, including your stress levels and the gut microbiome, influence allergies. That means taking care of your overall wellness by eating nutritious food, exercising, getting enough sleep, and keeping stress in check may pay off in allergy season, Marshall says.

People who aren’t able to manage their allergies through lifestyle changes or over-the-counter remedies may want to try immunotherapy, which involves repeatedly exposing someone to small amounts of their allergen until it no longer causes symptoms. Immunotherapy traditionally involves a series of injections, but there are also oral tablets for allergens including ragweed, some grasses, and dust mites.

Immunotherapy, Pien says, is the most scientifically sound way to get over an allergy, regardless of when in your life symptoms started.