Health Encyclopedia

Allergens: Pollen

What is pollen?

Pollen is the tiny egg-shaped male cells of flowering plants, including trees, grasses, and weeds. Pollen is microscopic in size.

Pollen is the most common cause of seasonal allergic rhinitis, sometimes known as "hay fever."

Which plants produce pollen that cause allergic reactions?

Plants that have powdery granules of pollen that are easily blown by the wind, such as:

• Trees: oak, western red cedar, elm, birch, ash, hickory, poplar, sycamore, maple, cypress, walnut, catalpa, olive, pecan, and others.

• Grasses: timothy, Johnson, Bermuda, orchard, sweet vernal, red top, some blue grasses, and others.

• Weeds: ragweed, sagebrush, pigweed, tumbleweed, Russian thistle, cockle weed, and others.

Most flowering plants, such as roses, have heavier, waxy pollens that are not as easily wind-blown.

When is "pollen season?"

Each plant has a pollen season. It usually starts in the spring, but may begin as early as January in the southern areas of the US. The season usually lasts until November.

Can allergic rhinitis in pollen season be prevented?

To lessen the effects of allergic rhinitis during pollen season, the American Academy of Allergy, Asthma, and Immunology suggests the following:

• Keep windows closed at night and use air conditioning - which cleans, cools, and dries the air.

• Minimize outdoor activities early in the morning, between 5:00 and 10:00 a.m., when pollen is most prevalent.

• Keep car windows closed when traveling.

• Take a vacation to an area where pollen is not as prevalent - such as to the ocean.

• Take the medications prescribed by your physician.

• Don't spend much time outdoors when the pollen count is high.

• Don't rake leaves during pollen season.

• Don't hang bedding or clothing outside to dry.

• Don't grow too many indoor plants.