What Are the Most Common Allergens in Each Allergy Season?

Is there only one allergy season? It depends on the allergen you have a reaction to. Here are the most common allergens by season.

Seasonal allergies, also known as hay fever, affect approximately 8 percent of adults in the United States.

Depending on where you live, the start of a particular allergy season may vary. Many people experience allergies around spring when trees and plants begin to pollinate. But hay fever can trigger during the other seasons as well.

Discover the most common allergens by season and learn more about what you can do to reduce your symptoms.

Seasonal vs Perennial Allergies

Before we jump into common allergens, it’s important to note the difference between seasonal and perennial allergies.

As the name suggests, perennial allergies occur year-round or almost all year. Common culprits of this type of allergy include pet dander, dust, or mold. Perennial allergies aren’t affected by the changing seasons.

You might experience seasonal allergies only at a certain time of year. For instance, someone who only experiences sneezing and itchy or watery eyes in the spring likely are allergic to a spring allergen.

Depending on the climate where you live, it may be difficult to understand what causes your symptoms. That’s when seeing a doctor or allergist would be a good idea.

Most Common Allergens


In some areas of the country, spring allergy season can start as early as February. It can also last well into the actual summer months.

For many people, spring is the worst time for allergies because many of the allergens come from pollinating trees, weeds, and grasses.

In northern latitudes, many people are allergic to birch tree pollen. Cedar, pine, willow, alder, and poplar are just a few of the roughly 100 species of trees that cause allergies.

Although most people are only allergic to one type of tree, it’s possible to have another allergy due to a cross-reaction.

The grass is another common offender and allergen to watch out for. Common types of grass allergens include Timothy grass, Bermuda grass, and Kentucky bluegrass.


When the weather heats up you might expect allergens to die down. But once pollen season is over, many people struggle with grass and weed allergies in summer.

Ragweed, Russian thistle, sagebrush, cockle weed, and pigweed are some common allergens at this time of year.

Ragweed is one of the most common allergens for allergy sufferers in the Midwest or Eastern states. But even if you live elsewhere, ragweed pollen can travel for hundreds of miles on the wind.

Weed allergen levels are highest in the morning between 5 – 10 AM. For allergy and asthma sufferers, it’s best to limit your exposure during these hours.

Grass pollen also continues to be an issue in the summer, because grass pollen travels on the wind. When everyone starts to mow their lawns or a summer breeze kicks up, you’re more likely to breathe grass pollen in.


Again, the exact start date for seasonal allergies varies by region and weather conditions. Ragweed season usually begins in late summer or early fall, depending on your region. In much of the United States, ragweed levels are highest in early or mid-September.

Did you know a single ragweed plant can produce one billion pollen grains each season? Considering how lightweight the pollen is and how far it can travel, it’s no wonder that so many people suffer from ragweed allergies.

Other common weed allergens include goldenrod, pigweed, sheep sorrel, sagebrush, and curly dock.

Mold allergies also become a problem in the fall. Mold grows well in dark, moist areas like compost piles. Mold can also grow on the dead leaves that cover the ground.

So if you have a mold allergy, you might want to think twice about jumping in that leaf pile.


In winter, most people spend more time indoors meaning indoor allergies tend to be more of an issue. These indoor or perennial allergies tend to come from allergens inside your home.

When the heat kicks on, it pushes dust, mold spores, and insect droppings into the air. Since there tends to be less ventilation in winter, we breathe these contaminants in and they cause a reaction.

Mold spores are a common cause of allergic reactions. Mold thrives in dark and damp rooms like the basement and bathroom. Dust mites and pet dander are two other common allergens that bother people when they’re inside more often in the winter.

Is It a Cold, the Flu, or Allergies?

So how do you know if it’s a cold, the flu, or allergies causing your symptoms? All three can cause similar symptoms, after all.

Is it allergy season where you live? If so, do you usually get sick around the same time each year? If you said yes to both, it may be the result of hay fever rather than a cold or the flu.

Compare your symptoms to determine the root cause of your suffering. Some common symptoms of a cold and the flu are aches, pains, and a high fever. These usually aren’t symptoms of allergies.

Seeing an Allergist

If your symptoms persist or your allergies interfere with your daily life, speak to a doctor. Your doctor may refer you to an allergist, who can then test you for various allergies.

Your doctor may prescribe antihistamine medication to help you manage your symptoms. In the meantime, find out more about what you can do to deal with seasonal allergies.

Managing Your Symptoms During Allergy Season

If you suffer from seasonal allergies, it can seem like you’re fighting a losing battle against nature. But we know more about allergens today than ever before so you can protect yourself.

The best way to understand how allergens affect you is to see an allergist. They can test you for specific allergies so you can prepare before allergy season hits.

During allergy season, check for high pollen counts and avoid times when pollen peaks. When you come home, take off your shoes and clothes and take a shower. This reduces the amount of pollen that you’re breathing in.

Use these tips to manage your symptoms and breathe easy again.

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One Comment

  1. It’s great that you pointed out how hay fever could trigger during other seasons as well. My sister showed an allergic reaction earlier and she can’t seem to find the cause of it. I think it would be better for her to know her allergies, so she should probably ask for allergen testing later.

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