Adapting Allergy Care Due to Increased Pollen Seasons, with Sharmilee Nyenhuis, MD

Climate change has recently extended pollen seasons, ultimately affecting allergy care.

“[The pollen seasons] expanded much longer than they did previously, and it's affected different parts of the United States more than others,” Sharmilee Nyenhuis, MD, from the University of Chicago, told HCPLive at the 2025 American Academy of Allergy, Asthma, & Immunology (AAAAI) in San Diego on her team’s session, “Allied Health: An Overview of Allergic Rhinitis and the Impact of Climate Change on Allergies.” “The west coast and the Southwest seen almost a 20-day increase in freeze days, so again, that lengthens the pollens.”

Nyenhuis added how air pollution also impacts the pollen allergen level, with diesel particles making the pollen more allergenic.

“With that, we are seeing in patients with allergic rhinitis that they have symptoms for a longer period of time and sometimes even more severe symptoms,” Nyenhuis said.

Nyenhuis shared ways to improve rhinitis allergic symptoms within the home, which includes air filtration by using bathroom and kitchen fans. Outside, people can wear a regular surgical mask if they are worried about pollen and an N95 mask for air pollution.

Patients with allergic rhinitis can opt for subcutaneous or sublingual immunotherapy, and Nyenhuis said they are both efficacious treatments. However, she chooses which immunotherapy type to give each patient based on several factors.

If people have multiple allergies, Nyenhus recommends subcutaneous therapy since it only requires about 1 – 3 shots, depending on the number of allergens, and it is taken weekly not daily. This can be helpful if patients have concerns about adherence. However, the US Food and Drug Administration (FDA) has only approved subcutaneous therapy for the allergens of grass pollen, ragweed pollen, and dust mites.

If the patient is allergic to something else, Nyenhuis recommends sublingual immunotherapy.

Overall, Nyenhuis said it is important for allergists to be aware of the lengthening pollen seasons. At the meeting, she also presented the importance of collecting hyper-local pollen data, rather than relying on weather apps that report pollen forecasts but use historical data.

“As things are changing, we might not be able to rely on that historical data as much, so some of the things to do is seeing if there is somebody who's actually doing the Pollen counting…and that data is collected from pollen counters and where people are actually measuring the pollen and then counting the pollen,” Nyenhuis said.

Accurate pollen counts can inform patients whether they should take precautions before leaving their houses. For instance, if they are allergic to grass pollen, and it is a high grass pollen day, they could wear a mask outdoors.

“I think a lot of it is awareness of what are the actual levels of pollen,” Nyenhuis said. “But also thinking about air quality as well and trying to get as much as possible this hyper-local data, because that'll be more representative of what you're experiencing… living in a large city, some areas may be more affected by pollen levels [than] others.”

Relevant disclosure for Nyenhuis includes GlaxoSmithKline.

References

Nyenhuis, S, Gregory, K, Strong, B. Allied Health: An Overview of Allergic Rhinitis and the Impact of Climate Change on Allergies. Session presented at AAAAI 2025 in San Diego on February 28.