July 7, 2022

Allergies in Denver: Here's What You Need To Know

Denver, Colorado is a great place to live, but it's not without its problems. One of the most common issues for residents of this wonderful city is allergies. Although you might think that Denver has no natural allergens, there are plenty to be found here. There are several types of allergens here in the Mile High City: pollen from trees, weeds, and grasses! This pollen comes from wind-pollinated plants, which means that their pollen travels long distances through the air before settling on surfaces like cars or houses where it can be inhaled by people with allergies. Let's take a look at some ways you can try to manage your allergies so that they don't get the best of you.

How long is the allergy season in Denver, Colorado?

Denver tends to have a cool and dry climate, that also experiences all four seasons. This means that there are different allergies to be wary of every season. The allergy season begins in February and goes through October. However, the most severe allergies tend to peak between April through September in Colorado.  

Common allergy symptoms include:

  • Sneezing
  • Itchy or watery eyes
  • Runny or stuffy nose
  • Congestion that may result in coughing
  • Trouble sleeping
  • Headaches

If these symptoms sound familiar to you, don't worry there are several effective treatments available including immunotherapy!

What are the most common allergens in Denver, Colorado?

Tree pollen is one of the most common allergies in Colorado. It can cause allergic rhinitis, which means that your nose and throat will begin to swell whenever you come into contact with it. The most common trees responsible for this type of allergy are:  Trees in Colorado usually begin pollinating around February through June.

Tree pollen:

  • Cottonwood and Aspen trees are fast-growing trees that heavily populate the Denver area. During their pollinating season (February through May), they release small particles into the air which can wreak havoc on your allergies as they blow into your throat, nose, and eyes. 
  • Elm trees are very popular in Denver due to the damp areas and rivers. These trees begin to bloom around February through April. 
  • Juniper (Cedar) trees are known to pollinate in the winter. This creates a lengthy allergy season for allergy sufferers in Denver because once the first cold front hits, these trees begin to pollinate. 
  • Oak trees can cause severe reactions. These trees mainly pollinate around the spring months of February through May. 

These symptoms usually occur during springtime because that’s when these trees bloom--and then late on in the summer months as well--but some people experience them year-round if they're especially sensitive to tree pollen! 


It's easy to forget about the plant life that surrounds you when you're out enjoying all the outdoor activities Colorado has to offer, but things like ragweed and tumbleweeds can cause serious problems if they get in your lungs.

Weed pollen season typically begins in late July through September or even October in some years. The fall months in Colorado are lovely, but they come with a price: weed allergy season.

To avoid these allergens, make sure you always wear a mask when outdoors during this time of year—even if you don't think you'll be affected by them!

  • Tumbleweed season begins in July to October. Tumbleweed is known to populate dry and windy areas, making Denver its home. 
  • Sagebrush flowers from mid-August to late September can really affect those with asthma allergies. 
  • Ragweed is a major weed allergy. One grain of pollen of ragweed can release a billion grains into the air. Ragweed begins its pollinating season in July and goes through September, but usually peaks in August. 


Grass Pollen season runs from early May through August. The amount of pollen in the air depends on how dry it is outside during this time period; if there's a lot of moisture in the air from rain or snowmelt then fewer grains will travel far enough to become airborne allergens. If it's very dry outside then more grains become airborne allergens because they don't stick together as much while they're falling through space (like raindrops do).

  • Kentucky bluegrass is known by several names, including June grass, bird grass, or even green grass. While the pollinating season for Kentucky bluegrass is just from spring to fall, it still releases large amounts of pollen. 
  • Ryegrass is a short-lived perennial and is one of the most common grass allergies. It also releases large amounts of pollen during its flowering season. 

Allergy treatment in Denver, Colorado

At Aspire Allergy & Sinus we offer a variety of allergy treatments, servicing seasonal and environmental allergies. We have clinics located in the Lakewood area, serving the neighborhoods of Applewood and Daniels, but we’ve even seen patients from Golden, Colorado!  We also have a Castle Rock location right off I-25, servicing the Meadows, Sedalia, and Franktown areas. Dr. Darya Koenig is a board-certified allergist who offers comprehensive care for children and adults in food and environmental allergies and sinus services in the Castle Rock and Lakewood areas. Be sure to make an appointment with Dr. Koenig at one of our Denver clinics!

Allergy shots (Immunotherapy): this treatment helps desensitize you to allergens by exposing you to small amounts of allergens over time. It's one of the best ways to prevent allergic reactions from happening in the first place, instead of just treating them after they happen.

Allergy Drops (Sublingual Immunotherapy): This treatment is extremely easy and convenient as it can be taken at home, or anywhere between! Just three drops under your tongue and that’s it! 

ExACT Immunoplasty: ExACT Immunoplasty is a new innovative treatment that can eliminate your allergies in just 3 quick visits! This treatment is clinically proven to be just as effective as allergy shots! See for yourself just exactly what ExACT Immunoplasty can do for you! 

Denver is an amazing place to live and a great vacation spot as well. While mountaineering in the Rockies we want you to enjoy it without the added complications of allergies. If you’re tired of your allergies controlling your life, book your appointment online today!

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About The Author:

William Storms, MD

Dr. William Storms has practiced in Colorado Springs & Pueblo since 1975 and is a past Clinical Professor at the University of Colorado Health Sciences Center. He practices clinical allergy and clinical research at The William Storms Allergy Clinic in Colorado Springs, Colorado.