For some people, the onset of sneezing and coughing or eye and nasal itch during certain times of the year are the first warning signs of having seasonal allergies.

The most common triggers of seasonal allergies include grass, pollen, and mold. Your immune system attacks the inhaled allergens and releases chemicals called histamines. These histamines trigger allergy and asthma symptoms. (1)

In addition to grass, pollen, and mold, several triggers are often seasonally related, including: (2,3)

• smoke from summer campfires and winter fireplaces
• insect bites and stings in spring and summer
• pool chlorine that indirectly contributes to allergies by irritating the respiratory tract
• pine trees, Christmas trees and wreaths during the winter months

Every season brings its share of potential triggers affecting people with allergies. The following is an overview of some of those allergies.

Spring allergies

In most temperate climates, spring brings wind-blown seasonal pollens from trees, grasses, flowers, and weeds. For millions of people around the world, these seasonal pollens are powerful allergens that trigger life-disrupting allergic reactions.

Pollens are tiny grains ranging from 5 to 200 microns in diameter, though the majority of wind-borne pollens tend to be 15 to 35 microns (human hair diameter: 50 - 70 microns). (4) When airborne, they can enter your respiratory system, where your body treats them as invaders and releases antibodies for protection.

Summer allergies

Pollen, mold, and insect stings are the most common allergens during the summer months. These summer allergens can leave you with some unusual symptoms. You might want to consider seeing a board-certified allergist if you experience the following symptoms: (5,6)

• Allergic shiner: Dark circles under your eyes from swelling and discoloration of blood vessels under the skin. They look like a “shiner” you might develop if you’ve been hit near your eye.
• Allergic (adenoidal) face: Nasal allergies can trigger a swelling of the adenoids (lymph tissue lining the back of the throat and behind the nose). This can result in a tired and droopy look.
• Nasal crease: Constant upward rubbing to relieve nasal congestion and itching can result in a line appearing across the bridge of the nose.
• Mouth breathing: Allergic rhinitis (group of symptoms affecting the nose) can cause severe nasal congestion, resulting in constant breathing through the mouth. Some people will develop a high, arched palate, an elevated upper lip, and an overbite. Teens with allergic rhinitis might need braces to correct dental issues.

Summer allergy symptoms are often mistaken for colds and food intolerances. If your symptoms are persistent and last for more than two weeks, you should see your allergist.

Fall allergies

Ragweed

One of the most common fall allergy triggers is ragweed pollen. This yellow flowering plant begins to bloom in August, then continues into the fall months until cold weather kills it off. In warmer climates, ragweed can flourish all the way into the winter.

Ragweed pollen can travel easily on the wind, affecting people with allergies even if it doesn’t grow nearby.

While ragweed is native to North America, the plant is an invasive species. Ragweed has been introduced to Europe, where it is common to northern Italy and southern France. (7)

Winter allergies

The most common winter allergen comes from mold found in Christmas trees, also known as “Christmas Tree Syndrome.”

Christmas trees are cut, baled, and packed into refrigerated trucks to be delivered to a tree seller near your home. Along the way, moisture and the tight bundling of the trees supports an ideal environment for mold to grow.

Once the tree gets into your home, mold on the tree may begin reproducing, triggering the allergic reaction – Christmas Tree Syndrome. Many of the mold varieties found on Christmas trees are those most likely to trigger allergies.

Year-round allergies

Dust mites

Dust mites can trigger allergies any time of year. These microscopic insects feed off the flakes of skin shed naturally by your family and pets.

A 2015 study published in the Journal of Allergy and Clinical Immunology found that between 65 to 130 million people worldwide are sensitive to proteins found in the mites’ bodies and feces. (8) As many as 50 percent of asthmatic people are sensitive to dust mites.

When you turn on your furnace after a long period of little to no use, mite waste can be blown all over your home, causing allergies to flare.

Mold allergies

Mold spores breed outdoors in fallen leaves, gardens, compost piles, and yard waste. The spores are small, light, and easily inhaled into the lungs. Mold spores are a powerful allergen that can cause the immune system to overreact, resulting in coughing, restricted breathing and asthma symptoms.

Weather patterns and seasonal allergies

While the timing and severity of an allergy season can vary, there are time-of-day and weather factors that can influence the severity of your allergic reactions.

• tree, grass and ragweed pollens thrive during cool nights and warm days
• molds grow quickly in heat and high humidity
• pollen levels tend to peak in the morning hours
• rain washes pollen away, but pollen counts can soar after rainfall
• airborne allergens are grounded when wind is absent
• pollen counts surge during warm, windy days

Allergens are virtually everywhere, so relocation isn’t a true solution

How to control seasonal allergies

Whether you and your allergist decide to address your allergies with medication and/or immunotherapy, allergy prevention is a critical first step in managing symptoms.(9)

• Give your home regular thorough cleanings.This includes using a HEPA vacuum cleaner on all rugs, carpets, and draperies.
• Rake your yard of fallen leaves and other dead vegetation, and don’t leave piles sitting on the lawn.
• Clean out gutters and compost bins regularly. It’s a good idea to wear an allergy mask, such as an N95 particulate respirator, to filter pollen and mold while doing yard work. Clear safety goggles will also help.
• Monitor the pollen and mold count in your area. On days when they are high, stay indoors as much as possible and keep doors and windows closed.(10)
• Bathe your pets and/or wipe down their fur regularly to remove pollen and mold.
• Pollen and mold sticks to clothing, skin, and hair, so remove jackets and shoes before coming into the house and change into fresh clothes once inside. Also, bathe or shower before going to bed each night to keep it from getting on sheets and pillowcases.
• Wear an air pollution mask to reduce your exposure to allergens when you're outdoors or in heavily polluted areas. An air pollution protection mask can filter virtually all pollen and other allergens from the air you breathe.
• Use a powerful air purifier for allergies to stop allergens before they trigger a reaction.

The takeaway

Seasonal allergies are a nuisance, but vigilance can stop them from impacting your quality of life.

You can prevent allergy flare-ups in your home and improve your air quality by staying informed, taking preventative actions, and cleaning the air in your home or officeduring peak allergy season periods.