Fall allergies are caused by seasonal allergens that peak or increase during the autumn months. Mold, smoke, and ragweed are possible causes. Symptoms include nasal congestion, an itchy throat, and headaches.

Seasonal allergies account for a large number of total allergy cases each year, with roughly 24 million cases of seasonal allergies reported in 2018 out of roughly 50 million total allergy cases.

Seasonal allergies can cause symptoms such as itchy eyes and a runny or stuffy nose. Several potential causes, including mold and pollen, can contribute to fall allergies.

This article reviews the causes of fall allergies, common symptoms, diagnosis, treatment, and more.

A person walking on fallen leaves.Share on Pinterest
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Several factors can contribute to fall allergies. Many of the causes peak during fall months or become more prevalent during these months.


Fall is a prime time for mold growth and spreading in the outdoor air. Fallen leaves combined with rotting wood cause mold levels to peak in many areas.

Weather can also heighten the allergen. Dry breezes can spread mold spores, while warm, humid air can help facilitate their growth.

In most cases, mold allergies are like other seasonal allergies. However, some people allergic to aspergillus fumigatus may develop allergic bronchopulmonary aspergillosis. This condition can range in severity from mild to severe and cause symptoms similar to asthma.

Warmer temperatures

Warmer annual temperatures may be contributing to a rise in fall allergies.

Warmer temperatures extend the growing season. This can cause an increase in the pollen in the air.

Heat waves and droughts may also affect allergens. When they occur, the air can stay stagnant, causing increased ozone or worsening air quality that can negatively impact allergies.


Smoke is a known environmental irritant for many people. In some states, people burn leaves and other brush to clear their yards of natural debris. They may also start running wood-burning fireplaces or having campfires at night when the temperature drops.

The increase in smoke in the air can trigger allergic-like symptoms for some people.


Ragweed allergy affects up to 23 million people in the United States. While other pollen counts peak in spring and early summer, ragweed peaks in September and starts in mid to late summer.

There are over 17 species of ragweed, and it grows throughout most of the United States. The pollen is lightweight and can spread for miles on the wind.

Learn more about ragweed allergy here.

Fall allergies cause similar symptoms to those occurring at other times, such as hay fever. Hay fever, or allergic rhinitis, can be seasonal or year-round. Symptoms can include:

Learn about hay fever and its symptoms here.

Hay fever or seasonal allergic rhinitis is often not difficult for an allergist to diagnose. They will likely ask about a person’s symptoms and may perform a physical examination.

If symptoms occur at certain times of the year and not others, they may diagnose a seasonal allergy.

An allergist can also help identify the exact cause or triggers of a person’s allergy. Fall allergies can have several causes, and knowing what to avoid can help reduce symptoms.

Treatment for fall allergies can involve a combination of medication and attempting to limit exposure to known triggers.

For some, an allergist may recommend immunotherapy, also known as allergy shots. Another recently approved treatment in the United States is sublingual immunotherapy, or allergy tablets. Both types provide long-term relief of allergy symptoms.

Doctors may also prescribe or recommend various medications to help treat symptoms. They can include:

A doctor or allergist will likely recommend a person start the medications about 2 weeks before they expect their symptoms to start.

Learn more about allergy medicine here.

In addition to medications, a person can take steps to limit exposure to allergens. Though it may be difficult to avoid contact with all fall-related allergens, the following precautions may help:

  • Monitor mold and pollen counts on local radio and TV weather reports.
  • Keep windows and doors shut at home, work, or in the car.
  • Wash hair, clothing, and skin after working or playing outside.
  • Know when pollen counts are highest and plan outdoor activities around it. For instance, ragweed tends to be worse in the morning.
  • Take allergy medications before heading outside.
  • Wear a NIOSH-rated 95 mask when outdoors mowing the lawn or doing other activities.

Not all areas of the United States have the same levels of common fall allergens. The following map shows some of the best and worst areas of the country for allergies.

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The most and least challenging U.S. cities for fall allergies, based on the Asthma and Allergy Foundation of America’s 2021 Allergy Capitals report.

A person should consider consulting a doctor if they experience symptoms of a seasonal allergy. If they tend to occur only at certain times of the year, an allergist will typically diagnose a seasonal allergy and provide medication and support.

If a person is running a fever or has additional symptoms, they should also consider talking with a doctor. They may find a different cause and recommend relevant treatment.

Fall allergies will typically start to clear once the triggers reduce. For example, ragweed pollen should decline after the middle of September.

Mold should also start to decline as the temperature starts to drop.

Smoke from fires may continue into the winter if people burn fires to heat their homes. However, it may be less frequent.

A fall allergy is a type of seasonal allergy that peaks in the fall rather than the spring. Common causes can include ragweed, mold, changes in overall weather, and smoke.

A person can typically treat allergies with a combination of medications and avoiding known triggers. As the season transitions to winter, a person should see their symptoms improve.