What Causes Seasonal Allergies?


Why do I have seasonal allergies?

Seasonal allergies are caused by your body identifying pollen from trees, grasses, or weeds as harmful. When you come in contact with pollen, your body releases histamine. Histamine causes allergy symptoms like sneezing, coughing, and congestion to get the pollen out of your body.

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What Are Seasonal Allergies?

Seasonal allergies, also known as hay fever and allergic rhinitis, happen when your body has an allergic reaction to pollen. Your immune system has mistakenly identified allergens in your environment as harmful, which triggers a defense response within the body.

As a result, your body releases a chemical, histamine. Histamine can make you sneeze, cough, have a runny nose, or have watery eyes to remove the allergens from your body.

What Causes Seasonal Allergies?

Seasonal allergies are caused by exposure to pollen from trees, grasses, or weeds. When these plants release pollen, and you breathe it in or come into contact with it, the pollen can trigger your allergies. You might notice your allergy symptoms are worse when pollen counts are higher.

When Is Allergy Season?

When allergy season takes place will depend on the plants you are allergic to and the climate you live within. Plants release pollen at different times throughout the year, so knowing what you are allergic to will help you know when allergy season is for you. Take an at-home allergy test to identify your allergy triggers, or continue reading to learn what types of plants release pollen in each season.


Seasonal allergies from tree pollen are prominent in the spring. Spring allergies usually start in February or March and go until April or May.


Grass pollen is prominent in the summer, so these summer seasonal allergies will usually go from May until July.


Weed pollen is prominent in the late summer and throughout the fall. Typically fall seasonal allergies will start in August and stop by November.


While most pollen allergies will stop during the winter, certain trees, like the mountain cedar, can still germinate in winter. Indoor allergens like pet dander, dust mites, and mold can also create issues for those with allergies if you spend extra time indoors during the winter.

Read more about the seasonal allergies in each state.

What Are Common Triggers?

Common seasonal allergy triggers are grass pollen, tree pollen, and weed pollen. While this is not a comprehensive list of allergens, here are some of the common plants to cause seasonal pollen allergies:

  • Ragweed
  • Sagebrush
  • Pigweed
  • Timothy grass
  • Bermuda grass
  • Ryegrass
  • Cedar tree
  • Birch
  • Maple tree
  • Cottonwood
  • Oak
  • Elm


The good news is you can treat seasonal allergies using medications like over-the-counter antihistamines, decongestants, topical nasal sprays, or immunotherapy. Over-the-counter medications only provide short-term symptom relief. Immunotherapy is the only way to fix allergies for the long term.

Immunotherapy introduces small doses of allergens to your immune system. Over time, your body becomes desensitized and stops reacting to the allergens that trigger your seasonal allergies. Immunotherapy comes in two forms: allergy shots and sublingual immunotherapy.

Sublingual immunotherapy, also known as allergy drops and tablets, is taken under the tongue instead of through an injection. Sublingual immunotherapy is just as effective as allergy shots, but it can be taken safely from the comfort of your home.

Take Our Allergy Assessment

If you have seasonal allergies and want long-term relief from your allergy symptoms, choose Wyndly. Our allergy doctors will create a personalized treatment plan to help you live free from seasonal allergies. Take our quick online assessment today to see if Wyndly is right for you!

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