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Allergy Season In Colorado: Allergens By Region + Symptoms & Treatment (2024)
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Allergy Season In Colorado: Allergens By Region + Symptoms & Treatment (2024)

Shuba Iyengar, MD, MPH
By Dr. Shuba Iyengar, MD, MPH Updated on Jul 08, 2024
Table of Contents

    Colorado, known for its stunning landscapes and outdoor activities, is also infamous for its allergy season. The state's diverse flora and fauna contribute to a variety of allergens that can make life uncomfortable for residents and visitors alike.

    Understanding Colorado Allergy Seasons

    In Colorado, allergy season typically begins in the spring and lasts through fall. However, the specific timing and severity of allergy season can vary depending on the type of plant pollinating and the region of the state.

    A Seasonal Breakdown

    Colorado's diverse climate and vegetation contribute to a prolonged allergy season that varies based on the time of year. Here's a detailed look at what to expect during each season.


    Spring is the start of allergy season in Colorado. During this time, tree pollen is the primary allergen. Trees such as cottonwood, ash, oak, and pine begin their pollination process, causing discomfort for many allergy sufferers. Symptoms can include sneezing, runny nose, itchy eyes, and more. Tree pollen tends to affect the eyes more than other pollens, like grass and weeds, do.


    As summer arrives, grasses take over as the main source of pollen. Common grasses in Colorado like ryegrass, timothy grass, Kentucky bluegrass, and Bermuda grass release their pollen into the air. This period is often referred to as "hay fever" season. In addition to the symptoms experienced in spring, individuals may also experience coughing and wheezing.


    Fall ushers in the weed pollen season. Weeds such as ragweed, sagebrush, and lamb's quarters are common in Colorado and release their pollen during this time. The symptoms remain similar to those experienced in spring and summer, but can become more severe due to the high concentration of weed pollen.


    Winter typically provides a respite from most outdoor allergens due to the cold temperatures and snowfall. However, indoor allergens like dust mites, mold, and pet dander can cause issues during this time. Symptoms can include itchy skin, difficulty breathing, and sinus congestion.

    Remember, while this guide provides a general overview, individual experiences with allergies can vary greatly.

    Allergens in Each Region of Colorado

    Colorado, known for its diverse landscapes and stunning natural beauty, is divided into several distinct regions. Each region has its unique characteristics, attractions, and, yes, allergens.

    Front Range

    The Front Range is the most populous region in Colorado, home to major cities like Denver, Boulder, and Colorado Springs. This region experiences a significant amount of tree pollen, particularly from cottonwood, ash, and oak trees during the spring season.

    Eastern Plains

    The Eastern Plains region is primarily rural, characterized by flat terrain and agricultural land. Here, grass pollens, such as ryegrass and timothy grass, are prevalent during the summer months.

    San Luis Valley

    This high-altitude desert valley is surrounded by mountain ranges. The San Luis Valley sees a mix of tree and grass pollens, but weed pollens, especially sagebrush, can be a primary concern in the fall.

    Western Slope

    The Western Slope encompasses areas west of the Continental Divide, including cities like Grand Junction. This region's allergy season is similar to the Front Range, with tree pollens dominating in the spring.

    Rocky Mountains

    The Rocky Mountain region, known for its ski resorts and hiking trails, generally has less pollen than other regions due to its high altitude. However, those sensitive to pine and spruce pollens may still experience allergies in the spring and early summer.

    Four Corners

    Located in the southwestern corner of the state, this region is part of the larger Four Corners area where Colorado, New Mexico, Arizona, and Utah meet. Similar to the San Luis Valley, the Four Corners region sees a variety of pollens, with an emphasis on weed pollens in the late summer and fall.

    Remember, wherever you are in Colorado, staying informed about local pollen levels and taking appropriate precautions can help you manage your allergy symptoms effectively.

    Managing Allergies in Colorado

    While it's nearly impossible to completely avoid allergens, there are several strategies you can use to manage your symptoms:

    • Stay informed. Keep track of local pollen forecasts and plan outdoor activities accordingly.
    • Limit exposure. Try to stay indoors on high pollen count days, especially during peak pollen times (usually mid-morning to early evening).
    • Create a safe space. Keep windows closed and use air purifiers to keep indoor air clean.
    • Medication. We recommend nasal sprays to help manage most symptoms. For severe allergies, consult with an allergist for prescription options.

    Colorado Allergy FAQs

    When is allergy season in Colorado?

    Allergy season in Colorado typically begins in spring (April) and lasts through fall (October). However, the specific timing can vary depending on the type of plant pollinating and the region of the state.

    How can I manage my allergy symptoms?

    You can manage your symptoms by staying informed about local pollen forecasts, limiting exposure to allergens, keeping indoor air clean, and using over-the-counter or prescription medications as needed.

    Are indoor allergies a concern in Colorado?

    Yes, indoor allergens like dust mites, mold, and pet dander can cause issues, particularly during winter when people tend to spend more time indoors.

    Can moving to a different region in Colorado help with my allergies?

    While some regions may have lower pollen levels due to factors like altitude or vegetation, moving isn't a guaranteed solution. Allergens can travel, and it's possible to develop new allergies. It's best to consult with a healthcare professional for personalized advice.

    Customized Allergy Treatment at Home

    Using multiple over-the-counter allergy treatments is not ideal for getting through allergy season in Colorado. Most allergists recommend and prescribe nasal sprays. This is because they are considered to be more effective. Nasal sprays go right to the nose to reduce inflammation and prevent it from spreading to the eyes and sinuses. Also, because nasal sprays go directly to the nasal tissue and not the rest of the body, they also usually have far less side-effects than pills.

    Skip the drugstore and get a personalized all-in-one allergy treatment from the comfort of your home.

    Allermi is a customized nasal spray designed by experienced, board-certified allergists to solve your unique seasonal allergy symptoms. The Allermi formula is backed by science to give you the most effective allergy treatment for your individual allergy symptoms. The best part? Allermi nasal spray is easy to use and delivered to your door in Colorado.