Ash pollen allergy

What it is

Ash pollen comes from trees in the genus Fraxinus, which belongs to the olive family, Oleaceae.² Nine ash species are native to the United States, including white, green, black, blue, Oregon and velvet ash.² AAFA rates ash as very allergenic, and it also lists olive, a member of the same family, among the trees that cause pollen allergy.¹

Ashes vary in how they carry their flowers. Some species have male and female flowers on separate trees, while others have flowers with both parts or a mix of the two. White, green and velvet ash are among the species with separate male and female trees.²

In white ash, the pollen is carried by wind, and a single tree usually sheds its pollen over 3 or 4 days.³ Wind-carried pollen is the only kind of tree pollen that most people with tree allergies react to.¹ University of Illinois Extension lists ash among the allergenic trees.⁴

Symptoms it causes

Like other allergy-causing pollen, ash pollen can trigger hay fever, also called allergic rhinitis, when it gets into the body.⁶ 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

If you have asthma and are allergic to tree pollen, the pollen can trigger your asthma symptoms. This is called allergic asthma.¹ People with asthma may be more sensitive to pollen.⁶ Hay fever symptoms generally end once exposure to the pollen ends.⁵

Where and when it grows

Ash grows mostly in the eastern and southeastern states, but it is found in most of the country except Alaska and Hawaii.¹ White ash grows naturally from Cape Breton Island, Nova Scotia, to northern Florida, and west to eastern Minnesota and eastern Texas.³ Green ash ranges from Cape Breton Island to Alberta and south to Texas and northwest Florida. Oregon ash grows from Puget Sound in Washington to southern California, and velvet ash from Utah and Nevada south to southern California and southwest Texas.²

Most ashes flower in spring, with or just before the leaves.² Carolina ash flowers in February and March, blue and velvet ash in March and April, green ash from March to May, white and Oregon ash in April and May, and black ash in May and June.² In white ash, it takes 2 to 3 weeks from the first swelling of the male flower buds until the pollen sheds.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