If you never had allergies until now and suddenly spend every spring sneezing, you’re not imagining it. Yes, you can develop allergies as an adult. The American Academy of Allergy, Asthma & Immunology notes that about 20% of people with hay fever first develop symptoms after age 20. A study published this fall in the journal Immunity also offers a new explanation for why repeated exposures can turn a harmless pollen into a problem.
Dr. Brad Bichey, a board-certified otolaryngologist who sees allergy-driven sinus problems daily at Indiana Sinus Centers in Carmel and Fort Wayne, walks through what the research shows and what to do when allergies show up later in life.
Adult onset allergies are common
Allergies are often thought of as a childhood problem, but the numbers say otherwise. In the CDC’s 2024 National Health Interview Survey data, 25.2% of U.S. adults had a diagnosed seasonal allergy. The rate peaked at 27.7% in adults ages 45 to 64, higher than in adults under 45. Women reported seasonal allergies more often than men, 29.5% versus 20.7%.
So the question isn’t really whether adults can develop an allergy. It’s why the immune system starts reacting to something it ignored for decades, and whether that reaction will last.
How allergies develop
An allergy is the immune system mistaking a harmless substance, such as pollen, dust mites or pet dander, for a threat. This overview of what allergies are explains the basic types, from seasonal allergic rhinitis to year-round reactions to indoor triggers. The reaction doesn’t happen on first contact. The body has to be exposed, become sensitized, and then react on later exposures.
New research: your nerves may remember allergens
In September 2026, researchers at Mass General Brigham reported in Immunity that sensory neurons, the nerve cells that sense itch, can keep a “memory” of earlier allergen exposures. In mice, an exposure too small to cause an allergic response on its own primed these nerves through a signaling pathway called mTORC1, so the next exposure produced a stronger reaction.
The priming also carried over to other allergens with similar enzyme activity, which may help explain why one allergy can make you more prone to others. The nerve memory faded over time. This was a mouse study, so it doesn’t change treatment yet, but it fits what Dr. Bichey hears from patients: symptoms that build over a few seasons rather than appearing overnight.
Why allergies start or get worse in adulthood
Most adult-onset allergies trace back to exposure. As Cleveland Clinic allergist Dr. Dylan Timberlake puts it in Cleveland Clinic’s guide to developing allergies later in life, every exposure to an allergen is another chance for the immune system to react. The same guide lists moving to a new area, hormonal changes such as pregnancy or menopause, and stress as common factors.
Moving to Indiana is a good example. Tree pollen starts in spring, which ISC covers in its guide to spring allergies in Indiana, grass follows into early summer, and ragweed season runs from mid-August until the first frost. Someone new to the state can go a season or two without symptoms and then start reacting once those exposures add up. The daily Indiana sinus forecast shows which pollens are high on a given day.
Family history matters too. Allergies run in families, though you won’t necessarily react to the same things your parents do. Can allergies get worse over time? Yes. Steady exposure and new sensitizations can make each season feel harder than the last.
Is it allergies or something else?
New nasal symptoms in adulthood aren’t always allergies. A cold usually clears in about a week, while allergies follow the pollen calendar and bring itchy eyes and sneezing. ISC’s guide to telling seasonal allergies from a sinus infection covers the differences.
A runny nose triggered by cold air, strong smells or spicy food, with no itching, may be non-allergic rhinitis, which this article on chronic runny nose and non-allergic rhinitis explains. And allergies that go untreated can keep the sinus lining swollen, which is why Dr. Bichey looks at the connection between allergies and sinusitis when facial pressure and thick drainage show up.
Can you grow out of allergies?
Children often outgrow some allergies. Adult-onset allergies are different. Cleveland Clinic notes that allergies appearing later in life tend to stick around, though they can be controlled with avoidance, medication or allergy shots.
Can allergies go away on their own in adults? Sometimes symptoms ease for a few years and come back, but planning on that isn’t a strategy. The Mass General Brigham team is studying whether the nerve memory can be reset, which could one day help prevent allergies, but that work is still in the lab.
What to do if you develop allergies as an adult
Start by identifying the trigger. Allergy skin testing places small amounts of common allergens on the skin and reads the results in about 15 to 20 minutes. You’ll need to stop antihistamines for several days beforehand.
For treatment, the American College of Allergy, Asthma and Immunology calls nasal steroid sprays the single most effective drug class for allergic rhinitis. Dr. Bichey usually starts there, and ISC’s guide to using Flonase correctly covers technique. Saline rinses help clear pollen from the nose. Immunotherapy, given as allergy shots or under-the-tongue tablets, is the only treatment that changes how your immune system responds. Shots typically run three to five years.
If symptoms last past two seasons of over-the-counter treatment, or you start getting sinus infections every spring, it’s time for a specialist. This guide to Midwest allergy symptoms and when to see a doctor lists the warning signs, and this comparison helps you decide whether to see an ENT or an allergist.
Frequently asked questions
Why did I never have allergies until now?
Allergies need repeated exposure to develop. A move, a new pet, or years of breathing the same pollen can eventually tip your immune system into reacting, and hormonal changes can lower that threshold.
Are allergies genetic?
Partly. Having a parent with allergies raises your risk, but you can develop allergies with no family history, and you may react to different allergens than your parents.
Getting new allergies under control
Allergies that start in adulthood are common, and they usually don’t fade on their own. Finding the trigger and treating the nose early keeps seasonal symptoms from turning into chronic sinus trouble. If new allergies are wearing you down, schedule a visit with Dr. Bichey at Indiana Sinus Centers in Carmel or Fort Wayne.
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