Weeds release tiny particles called pollen—some you can see, some you can’t. Because of their microscopic size, weed pollen easily travels in the air and can get in your eyes, nose, or lungs. Everyone breathes in weed pollen, but not everyone has a reaction to it.

These symptoms are part of a reaction that is commonly called hay fever (even though weeds are not hay) - but is more appropriately called allergic rhinitis. If you have a weed pollen allergy and go outside on a day when it’s in the air, you’re likely to experience irritating symptoms like watery eyes or a runny nose.

Keep in mind that weed pollen, like grass and tree pollen, can travel far on windy days, so your reactions may not be because of the weeds in your yard or neighborhood. The source of your allergies could actually come from weeds miles away.