Oak pollen allergy

What it is

Oak pollen comes from trees in the genus Quercus, the largest group of trees native to the United States.² About 58 tree species and 10 shrub species of oak are native to the country. They range from white oak, found from southwestern Maine to northern Florida and eastern Texas, to live oak on the Coastal Plain from southeastern Virginia to southern Texas and interior live oak in the foothills of California’s Sierra Nevada and Coast Ranges.²

Each oak carries both male and female flowers, and the male flowers grow in clustered catkins.² Oaks are among the trees that make huge volumes of wind-dispersed pollen, and those are the species that usually cause problems for people with allergies.⁴ Pollen this dry and light can travel several miles on the wind.⁴ AAFA rates oak pollen as very allergenic.¹

Oak pollen contains an allergen, Que a 1, from the same group of proteins (PR-10) as birch pollen’s main allergen, Bet v 1. A 2015 review reports that these related allergens cross-react across oak, birch and their relatives.⁵

Symptoms it causes

Like other allergy-causing pollen, oak pollen can trigger hay fever, also called allergic rhinitis, when it gets into the body.⁷ Common symptoms of a tree pollen allergy include a runny or stuffy nose, postnasal drip, sneezing, an itchy nose, eyes, ears and mouth, and red, watery or swollen eyes. Some people also cough, wheeze or feel short of breath.¹ Hay fever symptoms generally end once exposure to the pollen ends.⁶

If you have asthma and are allergic to tree pollen, the pollen can trigger your asthma symptoms. This is called allergic asthma.¹ Pollen exposure is linked to asthma attacks and to more hospital admissions for breathing problems.⁷

Where and when it grows

Oaks grow in every state except Alaska and Hawaii.¹ Across the genus they flower in spring, from February to May, before or as the leaves come out.² White oak, which grows through most of the eastern United States, flowers from late March to late May, depending on latitude.³ Across the US, trees as a group release the most pollen from February through April, and in the South they can start as early as December or January.¹

Weather moves the timing around. White oak normally finishes releasing its pollen within 3 days, but stretches of wet weather delay shedding, and dry winds and freezing weather can harm flower development and pollen release.³ Over longer periods, climate change may raise the amount of pollen in the air and lengthen pollen seasons.⁷