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Is climate change affecting seasonal allergies?

Published: July 18, 2023

Written by: Cheryl Solimini

Mom carrying her daughter on her shoulders while laughing in a wooded park.

Shifting weather patterns are creating longer, harsher allergy seasons — bad news for seasonal allergy symptoms. Here’s what to know about how that can affect health.

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Sneezing, wheezing, sniffling… think that seasonal allergy symptoms feel worse and drag on longer each year? Well, it’s not just in your throbbing head. Research suggests that climate change and longer allergy seasons are related — bad news for the 25 percent of adults in the U.S. who suffer from seasonal allergies.

Pollen season now kicks off in North America about 20 days earlier and hangs on about 8 days longer than it did 30 years ago, according to research led by William Anderegg, PhD, associate professor of Biology at the University of Utah. Additional research from the University of Michigan predicts that by the end of this century, springtime allergy misery could start as much as 40 days earlier and last up to 19 days longer.

Climate change and high pollen counts explained

Climate scientists have concluded that the use of fossil fuels, such as gas and coal, have raised the atmosphere’s carbon dioxide (CO2) content by 50 percent in less than 200 years. CO2 traps the sun’s heat, leading to rising surface temperatures, which in turn affect growing seasons and weather patterns. Together, these conditions create the perfect “hothouse” for rising pollen counts — and allergies that affect your nose and eyes.

“Warmer temperatures cause plants to start flowering earlier in the spring,” explains Anderegg. “Under higher CO2 levels, plants tend to grow larger and produce more pollen per plant.” Annual pollen counts have increased by 21 percent since 1990, which means that these powdery grains produced by plants, trees and grasses are an increasing nuisance, bringing on more allergic reactions.

Seasonal shifts are occurring nationwide. “The largest changes in pollen levels were in Texas and the midwestern U.S.,” Dr. Anderegg says. Because many allergy-causing plants depend on the wind (rather than insects) for pollination, their pollen can be carried hundreds of miles through the air. So, urban, suburban and rural areas are all affected.

Climate change may also be linked to more frequent and intense thunderstorms. These storms can break pollen grains into smaller particles that penetrate deeper into nasal passages and lungs.

What are seasonal allergy symptoms?

As pollen counts increase and pollen grains travel greater distances, people who were previously unaffected by seasonal allergies may find themselves experiencing symptoms. Symptoms of seasonal allergies (also known as allergic rhinitis) include fatigue, nasal congestion, runny nose, sneezing and watery eyes.

For some sufferers, pollen can also trigger asthma, a more serious and life-threatening condition, says Jeffrey G. Demain, MD, founder of the Allergy, Asthma and Immunology Center of Alaska and a clinical professor at the University of Washington School of Medicine in Seattle.

Thankfully, there are short- and long-term strategies that may help ease the worst of sneezing season. Dr. Demain stresses the importance of identifying and treating allergies, especially in children, as early and effectively as possible. Research has shown that seasonal allergies take a significant toll on work and school performance and even on one’s social life. “Allergic rhinitis doesn't just make your nose run — you feel flu-ish. You can’t sleep at night. You’re congested. Your eyes itch and tear. And these are all things that have a tremendous impact on someone’s quality of life,” he says.

How does someone identify a pollen allergy?

“The first step is to know what you’re allergic to,” says Dr. Demain. If sneezing starts in the spring, it’s most likely in reaction to pollen from trees common to the area. Summer symptoms are usually triggered by grasses. Fall is ragweed season, though other weeds like pigweed release irritating allergens, too. Yet, with growing seasons lasting longer, these types of allergies may overlap.

An allergist can help pinpoint which plants are triggering the reaction and rule out other causes, such as household mold or dust mites. The quickest and easiest diagnosis is through a skin prick test. Small amounts of the usual offending allergens are applied on the forearm or upper back to see if red, itchy bumps arise at those spots.

Pollen precautions

With better information about what’s causing allergy symptoms, people can track pollen counts through news and weather forecasts. When the levels of a concerning allergen are set to reach high levels, several precautions can help limit exposure:

  • If allergy symptoms are pronounced enough, it may be wise to consider staying inside with the windows closed. If traveling by car, closed windows can help minimize exposure.
  • Pets can bring in pollen, so it may help to keep a dog or cat inside or wipe down their coat and paws before reentering the home.
  • After time outdoors or working in the yard, remove clothing and drop them in the washing machine. Take a shower, or at least wash your hands to remove pollen.
  • Use high-efficiency particulate air (HEPA) filters like the Crane HEPA Air Purifier to sift out allergens that sneak indoors. Dr. Demain suggests setting these portable devices in the family room and bedrooms.
  • Time activities. Trees and weeds pollinate in the morning, while grasses release more pollen in the morning and evening. People who want to hike or bike might consider doing those activities in the afternoon.

Wearing a well-fitting surgical face mask or an N95 face mask, like the 3M Aura Respirator N95 flat-fold mask, outside can help, too.

How to help treat seasonal allergy symptoms

At the first all-too-familiar signs of sneezing and sniffling — or even before symptoms start — consider arming yourself with seasonal allergy support products. But before you take any of these medications, talk with your health care provider. You’ll want to be sure they’re safe with other medications you may be taking or health conditions you might have.

  • Over-the-counter antihistamines block the action of a substance called histamine, which triggers allergy symptoms in the body. Examples include: CVS Health® cetirizine hydrochloride tablets for all-day allergy relief and Claritin nondrowsy allergy-relief tablets.
  • Nasal steroid sprays reduce swelling and mucus production in the nose. Using it from the start of pollen season is a good way to reduce symptoms while those allergens are in the air. Examples include: CVS Health fluticasone nasal spray
  • Nasal antihistamines offer a quicker delivery of antihistamines and combining them with nasal steroid sprays may work better than using either product alone. Examples include: Astepro Allergy steroid-free antihistamine nasal spray
  • A neti pot or saline spray can help flush pollen out of the nasal passages. This also stimulates the tiny hair-like structures called cilia inside your nose that naturally clear out your sinuses, adds Dr. Demain. Examples include: CVS Health sinus wash neti pot kit or CVS Health saline nasal moisturizing spray
  • For red-eye sufferers, eye drops may be a good choice. You can find products that contain antihistamines to help reduce itchy eye symptoms. Examples include: Pataday Once Daily Relief extra-strength eye drops, Systane Zaditor eye drops and CVS Health Eye Itch Relief eye drops
  • If nonprescription remedies don’t do the trick or you’re prone to asthma, allergy shots (allergen immunotherapy) may be an option. These treatments help your body build up immune tolerance to allergens. They’re given in a doctor’s office weekly and then monthly for three to five years. “For the majority, symptoms are controlled and benefits continue after discontinuation,” says Dr. Demain “There may be a recurrence of some symptoms, but they are typically mild.”
  • Another prescription option is sublingual immunotherapy (SLIT). Recently approved in the United States to treat ragweed, dust mite and some grass pollen allergies, these tablets dissolve under the tongue and are taken daily at home. They’re more convenient than shots, with no need for an office visit each time. Ask your health care provider if prescription medication may be needed to treat your allergy symptoms.

This content is for informational purposes only and is not medical advice. Consult with your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.