Background

The most ordinary trees, grasses, and weeds manufacture pollen, often in extraordinary amounts. These tiny, light, and dry particles are built for wind transport and can remain airborne for hundreds of miles. Although spring and fall are the primary seasons for hay fever (seasonal allergic rhinitis), those who live in milder climates may experience allergies year-round. Because variations in temperature and rainfall affect how much pollen is in the air, some seasons and years will be worse than others.

Incidence and Prevalence

An estimated 15-20% of the United States population, 44 to 58 million Americans, experiences some degree of hay fever. The condition is found in equal percentages among men and women and can be triggered by inhaling or touching pollen.

Cause and Risk Factors

Pollen can get into the airways (mouth, nose, throat, and lungs) through breathing or linings of the eyes. Once into the body, the pollen particles interact with the immune system, triggering hay fever symptoms. The most common of these symptoms are itchy, puffy, and watery eyes, sneezing, and a running nose or nasal congestion. In more severe cases, airborne allergens can cause reduced lung capacity and difficulty breathing. Contact allergies can manifest in hives or skin rashes.

Risk factors for hay fever include family members, especially parents, with allergies, frequent exposure to pollens, other allergic conditions such as eczema or asthma, and nasal polyps (small, non-cancerous growths in the lining of the nose).

List of Allergens

Grasses

Alfalfa

Aloe

Aster, China

Azalea

Bahia Grass

Barley, Cultivated

Bermuda Grass

Bluegrass, Annual

Bluegrass, Kentucky/June

Brome Grass

Burrobrush

Bush, Rabbit

Cactus

Camellia

Canary Grass, Reed

Careless Weed

Carnation

Chamomile

Clover

Cocklebur, Common

Coltsfoot

Colza / Rapa

Corn, Cultivated

Dahlia

Dandelion

Dockweed, Yellow

Fennel, Dog

Fescue, Meadow

Forsythe

Foxtail, Meadow

French Marigold

Geranium

Gerbera

Goldenrod (European)

Groundsel Bush

Heather

Hyacinth

Iodine Bush

Ivy

Johnson Grass

Kochia/Firebush

Lamb's Quarter (Goosefeet)

Lavender

Lenscale

Lupine

Marsh Elder, Rough

Mexican Tea

Mugwort

Nettle, Common

Oat Grass Tail

Oat Pollen, Cultivated

Orchard Grass

Oxeye Daisy

Pellitory, Wall

Pigweed, Rough/Redroot

Plantain, English

Primrose

Ragweed, Common

Ragweed, False

Ragweed, Giant

Ragweed, Slender

Ragweed, Western

Red Top

Reed, Common

Rose

Rye Grass

Rye Grass, Perennial (Classical)

Rye Grass, Perennial (MCS)

Rye, Cultivated

Sagebrush, Common

Salt Bush, Annual

Salt Grass

Sheep Sorrel, Red

Spiny Pigweed

Sunflower, Common

Thistle, Russian

Timothy Grass

Tulip

Velvet Grass

Vernal Grass, Sweet

Water Hemp, Western

Wheat Grass, Western

Wheat Pollen, Cultivated

Willow Herb

Wing Scale

Wormwood/Sagebrush

Yarrow