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Common Outdoor Allergy Causes

Allergens are invisible particles in the air that can trigger your immune system. Your body may respond differently and overreact to allergens from trees, weeds, grass, ragweed, and mold.

Sometimes seasonal allergies are called hay fever because it was once thought that the smell of hay causes summertime illness. But despite the name, allergies are not an infection and do not cause a fever.1

Here are some of the most common outdoor allergy triggers:


Trees, grasses, and weeds produce pollen as part of their reproductive cycle, depending on the season and where you live. Tree pollen peaks in most places during the spring season, but it may start as early as January and as late as June. Pollen is a fine, powdery substance that is transported from plant to plant through wind, animals, and insects. You can’t see pollen, but it gets everywhere. It’s one of the most common causes of outdoor allergies.2


In the late summer and fall time, it’s ragweed season. Ragweed is a plant that grows throughout the U.S, especially in empty fields and roadside ditches. Even if you don’t live near ragweed, you can still have an allergy. Ragweed pollen can travel in the wind for long distances — it has even been found in the air 400 miles out to sea and two miles up into the atmosphere.3


Mold thrives in humid environments, and it can grow both indoors and outdoors. Mold produces spores that travel through the air, and mold allergy happens when your immune system overreacts when you breathe them in. Outdoor mold tends to grow on rotting logs, fallen leaves, and compost piles. Mold spores are most common from July to early fall.4

Outdoor Allergy Symptoms

Allergy symptoms can be more than annoying — they can make you miserable.

When your body encounters an allergy trigger, such as pollen or ragweed in the air, your immune system may overreact as if it is an invader. White blood cells trigger a chain reaction that leads to the release of histamine and other chemicals in your cells. Your eyes itch, you sneeze, and your sinuses create mucus — all to expel the invaders out of your body.

Here are some common allergy symptoms:

Sometimes severe symptoms can happen when your immune system has an extreme reaction to an allergy trigger.

  • The same triggers for outdoor allergies can also trigger asthma, making it hard to breathe because of swelling, mucus, and tightening of the airways.5

If you are having severe symptoms or difficulty breathing, see a doctor immediately.

Tips to Relieve Outdoor and Seasonal Allergies

Do you dread planning outdoor activities because you worry about itchy eyes or nasal congestion bringing you down? Do you get sick with allergies in the same month or season every year?

Don’t fear taking a breath of fresh air. If you know your allergy triggers, you can take simple steps to help prevent and relieve your symptoms, so you can enjoy the outdoors all year long.

1. Understand Your Outdoor Allergy Triggers

While you can’t see the tiny pollen or mold particles in the air, you definitely notice the symptoms. Do your allergies act up in the early spring? It might be pollen. If your symptoms are worse in the fall, it could be ragweed.

It helps to know what you are allergic to so that you can take steps to avoid it. You may need to see an allergy doctor who can figure out your allergy triggers and come up with a treatment plan. When they take your full medical history, it helps to keep a journal or log of when you have symptoms and if they occur at a certain time of day or season of the year. They may do skin testing to figure out which allergy triggers are causing your immune system to overreact.

2. Check Pollen Count and Plan Your Day

When you have outdoor allergies, you’ll want to know the months when pollen levels are high in your area. You can check your local forecast for outdoor pollen counts and plan your outdoor activities when counts are low.

Dry, windy days will blow pollen particles in the air— stay indoors on those days if you can. Rainy days can rinse the pollen away, so planning an outdoor trip or activity might be best when there is moisture in the air. But rainy weather can make things worse if you have a mold allergy because mold thrives in damp and humid environments.6

To learn more tips about traveling with allergies, visit our guide for allergies on the go.

3. Wear a Mask When Going Outside

When you are planning an outdoor activity, pack a mask that is specifically designed to filter out small particulates. You can reduce the amount of pollen you are exposed to by protecting your face. Invisible pollen and mold particles in the air are everywhere and can easily travel into your eyes, nose, and mouth. Especially on days when pollen is high in your area, a mask can create a physical barrier that keeps the allergy triggers out and helps you breathe easier. You can protect your eyes too with sunglasses or goggles.

4. Avoid Pollen and Mold by Mowing or Raking

Yard work might be making you sick — mowing lawns and raking leaves can stir up pollen and mold. See if someone in your family who doesn’t have allergies can do the gardening. If you can’t avoid outdoor chores, mask up and wear eye protection. When you come indoors after yard work, change your clothes and bathe immediately. Keep your lawn short — it reduces the amount of pollen that grass produces. And don’t forget to close the windows before you mow or rake.

5. Don’t Line-Dry Clothes and Sheets

You may not realize it, but hanging up your laundry outdoors might be making you sick with allergies. If you line-dry sheets, bedding, and clothing outdoors, the fabric acts as a trap for pollen and other allergy triggers in the air. When you bring your laundry indoors, you may be bringing in your allergy triggers right along with your clean clothes. Instead, use a dryer or hang up your clothes indoors.

Learn more about indoor allergy tips by visiting our guide on managing indoor allergies.

6. Take BENADRYL® Products To Treat Symptoms

If you have outdoor allergies, BENADRYL® can help. The antihistamine in BENADRYL® products blocks histamine in your body, giving you relief from allergy symptoms during the season you need it most.

For adults and children over 6 years old, look at BENADRYL® Allergy ULTRATABS® Tablets or BENADRYL® Allergy Dye-Free LIQUI-GELS®. For adults and children over 12 years old, BENADRYL® Allergy Plus Congestion ULTRATABS® has an antihistamine and decongestant to help with allergy symptoms, including nasal congestion.

Related Articles


  1. Cleveland Clinic. Allergic Rhinitis (Hay Fever). July 30, 2020. Accessed from:
  2. Asthma and Allergy Foundation of America. Pollen Allergy. February 2022. Accessed from:
  3. Asthma and Allergy Foundation of America. Ragweed Pollen Allergy. August 2019. Accessed from:
  4. Asthma and Allergy Foundation of America. Mold Allergy. October 2015. Accessed from:
  5. Asthma and Allergy Foundation of America. Asthma. January 2022. Accessed from:
  6. Asthma and Allergy Foundation of America. How Does Rain Affect Pollen Levels? July 31, 2017. Accessed from: