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Allergy Season In Illinois: Allergens By Region + Symptoms & Treatment

Allergy Season In Illinois: Allergens By Region + Symptoms & Treatment

Medically Reviewed By:
Dr. Shuba Iyengar, MD, MPH
Written by:
Katelyn Johnson, B.S., M.B.A, CMA
Published: Jan 09, 2023
Table of content

    Unfortunately, seasonal allergies are quite common across the United States. However, did you know that each state has distinctive environmental allergies? Due to the variety of climates, the peak season, severity, and diversity of environmental allergies can be localized to each state and even regions within the states. 

    Additionally, individuals all have their own sensitivity levels to different types of pollen. For example, you may have a severe tree pollen allergy while your friend is only mildly allergic to weeds. Learning what you may be allergic to by what is causing high pollen counts during the time you experience symptoms is a good alternative to getting allergy testing through a local allergist. Additionally, knowing when each pollen blooms can be helpful for lessening your allergy symptoms.

    Luckily, we’ve already done the research. Below is everything you need to know about allergy season in Illinois plus the allergens by region, a brief overview of common symptoms, and the best allergy treatments.

    When Is Allergy Season in Illinois?

    Allergy season in Illinois depends on which pollen allergies you personally have. However, pollen season, when plants are releasing pollen into the air, extends from March to about mid-October, so you can expect the possibility of symptoms during all, or several, of those months.  


    Illinois Allergens by Season

    Each season in Illinois brings about a different type of pollen that causes symptoms, so here’s what you can expect throughout the year. 

    Spring allergy sufferers in Illinois are likely allergic to tree pollen. March, April, and May, which are considered Spring, tend to be a severe allergy season because the warm weather triggers trees to release their pollen. Sometimes, if the weather warms up early, spring allergies can begin in mid-February.

    Grass pollen is a troublemaker during the summer months in Illinois. From about mid-May to late summer(August/September), high grass pollen levels plague those with grass pollen allergies. 

    In the fall (i.e. August to October), tree pollen and grass pollen have mostly stopped as the weather begins to cool. Weeds are the culprit for the majority of fall allergies in Illinois. Weed pollen reaches its peak during this time. 

    Winters are a reprieve for allergy sufferers. Due to the cold, harsh weather of Illinois, pollinating plants die off at the first freeze, leaving the air free of pollen. 


    Illinois Allergens by Region

    The three regions of Illinois have unique allergens to watch out for.

    Northern Illinois

    Northern Illinois, including areas like Chicago, Joliet, Rock Island, and Rockford, reaches its peak tree pollen counts around April, since the weather doesn’t warm up as quickly. The trees to watch out for include species of Oak, Willow, Hickory, and Ash. A few other trees like Walnut, Mulberry, and the European Privet cause Spring allergies in Northern Illinois as well. 

    When it comes to grass pollen, the primary species of interest are Bent grasses, Orchard grass, Common Timothy grass, and Perennial Rye grass. These can release pollen from late Spring to early Fall, with the peak occurring in mid-Summer. 

    Fall allergies caused by weed pollen in Northern Illinois are short-lived due to the first freeze coming early. Varieties of Amaranth, Wormwood, Ragweed, and Mustard weeds are the primary contributors to Fall pollen levels in the Northern area of the state.


    Central Illinois

    Central Illinois can be considered the areas around Champaign, Springfield, and Bloomfield. 

    This region experiences extended Spring and Fall allergies. In the Spring, tree varieties like Hickories, Oaks, Ash, Willows, Walnuts, and Mulberries are significant allergens. Fall allergens are predominantly Ragweed and Amaranth weeds. 

    The summer, which is the peak grass pollen season, sees species like Common Timothy, Bermuda, Perennial Rye, and Orchard grass causing problems in Central Illinois. 


    Southern Illinois

    Southern Illinois, which encompasses cities such as Belleville, Salem, and Benton, is the worst region in the state for seasonal allergies. Trees in the area include all of those from the Northern and Central areas of Illinois, plus additional varieties in the same categories. Pecan and Eastern Red Cedar are additional pollinating trees that are unique to Southern Illinois.

    Bent species of grass are significant during the summer in the area as well as Clustered and Nodding Fescue, Prairie Kholer’s. The standard Bermuda, Common Timothy, Perennial Rye, and Orchard grass found throughout the state are still a problem here as well. 

    Weed pollen comes from Ragweed, Wormwood, Mustard, and Amaranth varieties as we have seen throughout the state. However, Sagebrush, Halberd-Leaf Orache, and Pennsylvania Pellitory are unique weed species in the region. 


    Signs That You May Have Seasonal Allergies

    Seasonal allergies can also be referred to as hay fever or allergic rhinitis. Though there are many terms, they all refer to the allergic reaction of the immune system triggered by environmental allergens. Environmental allergens can be a variety of things from pollen, as discussed above, to pet dander, dust mites, or mold spores. 

    Seasonal allergic rhinitis or hay fever symptoms include itchy eyes, watery eyes, sneezing, runny nose, nasal congestion, and post-nasal drainage. Some people might experience other symptoms as well such as sore throat, cough, headache, and fatigue. 


    How To Reduce Allergy Symptoms

    There are three main ways to reduce allergy symptoms– medications, allergen immunotherapy, and lifestyle changes. Each of these addresses symptoms in a different way and has its own pros and cons. 



    Medications are by far the most common way to treat allergy symptoms. They can be divided into two categories. 

    The first category is oral medications, or meds that you take by mouth, such as Zyrtec, Allegra, or Benadryl. These are easy to take and widely available over the counter at your local drugstore. However, oral medications are absorbed throughout the entire body making them prone to causing side effects. 

    The second category, and the gold standard for allergy treatment, is nasal sprays. Nasal sprays are sprayed directly into the nose and absorbed into the nasal lining, reducing inflammation at its source. Nasal sprays often only treat one allergy symptom at a time, but come with far less risk of side effects. 

    Now, there is an even better option on the market with Allermi, a nasal spray for allergies that will treat all of your symptoms in one customized spray. Keep reading to learn more below. 


    Allergy Shots/Drops

    Another treatment solution for seasonal allergies is allergen immunotherapy which is also referred to as allergy shots. 

    This process starts with allergy testing to see which allergens you have an allergic reaction to. Then, those allergens are introduced to your immune system slowly over an extended period of time through an injection or drops under the tongue. 

    Allergy shots/drops can be highly effective, but it takes a long time, is typically expensive, and and usually take a year to have an effect. 


    Lifestyle Changes

    Lifestyle changes are the least invasive way to control allergy symptoms. This includes doing things like keeping the windows closed in your bedroom (to prevent the pollens from getting on your bedding), checking pollen counts, and avoiding extended periods of time outdoors when there are high levels of pollen. Additionally, you may also utilize an indoor air purifier or wash your sheets and clothing more often. 

    Essentially lifestyle changes include any action in your daily routine that you take to minimize your exposure to allergens. Keep in mind that though lifestyle changes can help mitigate mild allergy flare-ups, people with severe allergies will not be able to completely resolve their symptoms with lifestyle changes alone. 


    Illinois Allergy FAQs

    What are ragweed allergy symptoms? 
    Ragweed allergy symptoms that are caused by ragweed pollen include itchy, watery eyes, sneezing, runny nose, nasal congestion, and sore throat. 

    When is allergy season in Illinois? 
    Allergy season in Illinois extends from March until around mid-October, though each season has different culprits when it comes to pollen allergies. 

    Is Illinois a good state for allergies? 
    Illinois isn’t the worst state for allergies, but it is not the best either. In the winter, Illinois has very few pollinators which at least provides some relief for 3-4 months. 

    Customized Allergy Treatment at Home

    Using multiple over-the-counter allergy treatments is not ideal for getting through allergy season in Illinois. 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 Illinois.