The Most Common Outdoor Allergens in the United States

Sometimes, you feel like just walking out the door makes you sneeze or makes your eyes itch. And when you learn about all the possible allergens out there, that’s not shocking. Allergies are certainly common in Las Vegas, but they’re also a problem elsewhere in the United States, too. If you’ve ever wondered what gets fellow allergy sufferers elsewhere around the country, here are some of the most prevalent pollen and spore-producers by region.


In the Southeast, certain grasses, weeds, and trees cause more allergies than others. Some bloom around the year, while others are most active in certain months. Year-round, one of the top grass allergens is Bermuda. This grass grows year-round, which means it produces symptoms anytime. The most common tree allergies are associated with cedar, pecan, and oak. They are in full bloom from February through May. Nettle and ragweed are the most common weed allergens. They are most active from June through November.


In the Southwest, redtop grass causes the most grass allergies. This perennial grass is in peak bloom from May through July. Oak trees are to blame for many Las Vegas allergies, and they’re a problem across the Southwest, too. Other top tree allergies come from cedar and elm. The majority of weed allergies come from chenopod, which blooms from July through September.


If you’re in the Northeast, be aware that there are certain trees, grasses, and weeds to watch out for. Most grass allergies in this area of the US come from orchard and redtop, which bloom from May through August. The top trees responsible for allergies are birch, pine, and oak, which tend to bloom from February through June. Predominant weeds (and allergy triggers) in the Northeast are ragweed and stinging nettle. They’ll make allergies worse from August through October.


In the Midwest, the grass most likely to give you allergies is called brome. Brome, which is a perennial grass, emerges in spring and blooms through July. Midwestern trees most likely to give you allergies are elder, elm, and maple. They have a blooming season from early spring (March) through early summer (June).


If you live or spend time on the West Coast, you may be able to link your allergies to several common causes. In the grass family, grasses, such as sweet vernal can cause severe allergies. Sweet vernal is most active from March through November. Among trees, walnut and cedar are top allergy producers. They typically bloom from February through June. The weeds most often associated with seasonal allergies in the West are iodine bush and pigweed. Both bloom from April through November.

Although these allergens cause the most symptoms in these regions, there are many more possible allergens that can trigger reactions. If you’re not sure what is causing your allergies, you are best off getting tested. A top allergist, such as Tottori Allergy & Asthma Associates, can perform skin allergy testing to check for allergic reactions and prescribe treatment if necessary.