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The Causes Behind Seasonal Allergies

April 18, 2023

Seasonal allergies are exactly what they sound like: allergies to substances that only circulate at certain times of year. If you grapple with them annually, you’re in good company: 24.4 million experience “hay fever” (another term for seasonal allergies), according to the CDC.


Here’s what you need to know: 

What causes seasonal allergies?

Healthcare providers refer to substances that cause hay fever as “allergic triggers.” The primary culprits are grass, tree and weed pollens, but within each of those categories is a parade of plants ranging from timothy grass and ragweed to elm and walnut trees.

The pollen is spread by male plants, which shed it into the air in order to reproduce. It’s then picked up by wind and carried to female plants and, including (unfortunately) those with allergies. The prevalence and severity of allergies arising from pollen depends largely on where you live and what time of year it is, though the big “allergy seasons” are spring and fall.

Spring allergies typically peak in the first week of May, when grass pollination starts to surge and overlaps with tree pollination; a large swath of people with hay fever are allergic to both. The biggest trigger for fall allergies is ragweed, which is most prevalent on the East Coast and in the Midwest. Pollen levels from ragweed peak in early to mid-September. Mold spores from decaying leaves and plant matter are another common trigger.

How can I find out which seasonal allergy I have?

Common hay fever symptoms include:

  • Sneezing
  • Runny nose
  • Scratchy throat
  • Irritated eyes (allergic conjunctivitis)
  • Coughing
  • Nasal congestion
  • Itchy nose, roof of mouth or throat
  • Swollen, blue-colored skin under the eyes (allergic shiners)
  • Postnasal drip
  • Fatigue

If that sounds like you, you’re probably wondering what you’re allergic to and how to narrow it down. This may seem like a virtually impossible task in the early weeks of spring, when everything starts blooming at once.

If you want to get more insight into your allergic triggers, there’s good news. Allergy testing doesn’t have to involve skin pricks or appointments with specialists. It can be as simple as ordering a blood test.

Also known as a specific IgE blood test, an allergy blood test measures the concentration of specific IgE antibodies in the blood. Your body makes these antibodies when it misidentifies pollen and other allergens as harmful. The presence of specific IgE antibodies in a blood test can help pinpoint your allergy.

The results of your blood test, together with your detailed medical history and a physical examination, can help your healthcare provider develop a customized treatment plan that's right for you.

Unlike skin-prick testing, there's no risk that a blood test will trigger an allergic reaction. This is especially important if you or your child are at a higher risk for a life-threatening, anaphylactic reaction. And for infants and young children, a single needle prick for a blood sample may be less traumatic than the repeated scratching of a skin-prick test.




Purchase an Indoor & Outdoor Allergy Blood Test

Hay fever might seem like an unavoidable part of life if you’re afflicted, but knowledge is power—and you don’t need to be a doctor to purchase a specific IgE blood test through Labcorp OnDemand®. We offer an Indoor & Outdoor Allergy Test for the most common allergens found outside and inside your home, including pet dander from cats and dogs, that are known to trigger allergic reactions.


If you can figure out what type of pollen is causing your symptoms, you may be able to take proactive steps to stay away from it. For more information or to buy an allergy test, click here.