Ragweed: Fall's Public Enemy #1

Ragweed: Fall's Public Enemy #1

Written by Dr. Joel Gallagher, Allergy and Asthma Center of NC, Cone Health Medical Group

Common ragweed — Ambrosia artemisiifolia — might sound divine, but anyone with allergies knows it’s anything but heavenly. There are also other species of ragweed, all of which are allergenic and belong to the genus Ambrosia. These tough plants grow across nearly every corner of the U.S., thriving especially in the Eastern and Midwestern states.

Image 1. "Ragweed" by Austin Nature in the City is marked with Public Domain Mark 1.0.


The name Ambrosia comes from the Greek word for “food of the gods” or “drink of immortality.” Why Carl Linnaeus, the father of modern taxonomy, chose such an exalted name remains a mystery. The species name, however, is easier to explain: ragweed’s leaves resemble those of Artemisia absinthium, better known as wormwood — the plant used to make the legendary, and once hallucinogenic, drink absinthe.

Ragweed is an annual, meaning it dies each winter and sprouts anew from seed every spring. Don’t be fooled by its short life, though. Each plant can release up to one billion pollen grains in a single season! Hardy and opportunistic, it pops up where few others dare to grow — think cracked sidewalks, empty lots, and abandoned fields. Blooming from late summer until the first hard frost ragweed can have a lengthy “reign of sneeze”.


Image 2. A cluster of ragweed pollen grains under a microscope photographed by Forsyth County staff on August 25, 2025. Ragweed pollen grains can be anywhere from 15-25 microns. 

For allergy sufferers, ragweed is the ultimate nemesis. Its pollen triggers classic symptoms of allergic rhinitis: runny or stuffy nose, sneezing, itchy eyes, and that ever-annoying postnasal drip. Combating it means minimizing exposure — washing up after outdoor activities, keeping windows closed, and relying on HVAC filters — and, when necessary, using allergy medications like antihistamines, nasal sprays, or eye drops.

“Food of the gods”? Hardly. Those gods clearly never had to deal with seasonal allergies!

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