Weed Pollen

Nettle weed

Nettle weed

Weed pollen is produced and released by their male flowers. When the flower blooms their pollen is released and carried by the wind to pollinate their female flowers. This process of wind-pollination is the same method used by other pollen allergens such as: tree pollens and grass pollens. Since wind is unreliable, weeds produce a large amount of pollen to ensure that their female flowers are pollinated. Unfortunately, much of the pollen never reaches its desired location and instead irritates our eyes, nose, and lungs. Certain types of weed pollen can be very allergenic, specifically ragweed and mugwort, though typically they still aren’t as allergenic as tree pollens.

When is weed pollen season?

Weed pollen is during the late-summer and fall months, though it can vary depending on location and climate.

Which weed pollens cause hay fever?

Weed pollens that are most commonly associated with hay fever are:

  • Ragweed
  • Sorrel
  • Mugwort
  • Sagebrush
  • Plantain
  • Nettle
  • Fat hen

Which foods have cross-reactions with weed pollen?

Cross-reactions between weed pollen and foods can occur due to something known as oral allergy syndrome. With oral allergy syndrome you may experience an itchy mouth after eating raw fruits, vegetables, or nuts. The most common weed pollens responsible for oral allergy syndrome are ragweed and mugwort. If you have a weed pollen allergy you may experience cross-reactions with one or more of these foods: aniseed, banana, bell pepper, black pepper, broccoli, cabbage, cantaloupe, caraway, carrot, cauliflower, celery, chamomile, coriander, cucumber, fennel, garlic, honeydew, mustard, onion, parsley, watermelon, and zucchini. (To see a detailed oral allergy syndrome food list please click here.)

How do you diagnose and treat weed pollen allergies?

For more information regarding the diagnosis of weed pollen allergies related to oral allergy syndrome please click here.

For more information regarding the treatment of weed pollen allergies related to oral allergy syndrome please click here.

For more information regarding weed pollen allergies related to hay fever please click here.



Airborne Pollen & Allergy Season. (n.d.). Retrieved from Pollen.com.

Multiple: Hay Fever. (2009). In R.J. Frey and L.I. Lutwick (Eds.), UXL Encyclopedia of Diseases and Disorders  (Vol. 3, pp. 466-472). Detroit: Gale. Retrieved from Gale Virtual Reference Library.

Nowak-Wegrzyn, MD, A. (2012). Clinical Manifestations and Diagnosis of Oral Allergy Syndrome (Pollen-Food Allergy Syndrome). Retrieved from UpToDate.

Disclaimer: The information contained in this site is for educational purposes only, and should not be used as a substitute for a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition. Click here to read the full disclaimer.
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