Common Pigweed
Allergy Facts, Symptoms, and Treatment

Part of the amaranthaceae family, common pigweed is a summer annual that can reach a height of up to 2 meters (roughly 6.5 feet). Featuring a bushy spike at the top, common pigweed is found throughout the world, including locales such as Europe, the United States, Brazil, Korea, Spain, Mozambique, Mexico, Hungary, Germany, and Afghanistan. While some species are insect-pollinated and others are wind-pollinated, the pollen commonly induces asthma, allergic conjunctivitis, and allergic rhinitis (hay fever).1 Common pigweed aliases include carelessweed, common amaranth, and redroot pigweed.2

Where is common pigweed found?

Common pigweed is found throughout the world, including locales such as Europe, the United States, Brazil, Korea, Spain, Mozambique, Mexico, Hungary, Germany, and Afghanistan. Found in pastures and forages, common pigweed also lives in locals such as wild landscapes, roadsides, and agronomic crops.1

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Are there other allergens I could be sensitized to?*

Many patients with common pigweed allergy can experience symptoms when exposed to other allergens such as tree, weed, or grass pollens, making it difficult to determine which pollen is causing the symptoms, especially when pollen seasons are overlapping. This is called cross-reactivity and occurs when your body's immune system identifies the proteins, or components, in different substances as being structurally similar or biologically related, thus triggering a response.5 Other respiratory allergens that may cause reactions associated with common pigweed are certain weed, tree, and grass pollens including goosefoot and saltwort.5

If you experience an itchy mouth or throat after eating fresh fruit or raw vegetables, you may suffer from Oral Allergy Syndrome (OAS), sometimes called Pollen Food Allergy Syndrome (PFAS). This condition is caused by your immune system's reaction to similar proteins, or components, found in different allergens. It is quite common, with up to 25 percent of children with allergic rhinitis (i.e., hay fever) also suffering from OAS.6 Common plant foods involved in OAS for common pigweed include melon, watermelon, citrus, banana, pineapple, persimmon, zucchini, tomato, hazelnut, peanut, and many more.5

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

How do I manage my allergy?

The management of allergic rhinitis includes avoidance of relevant allergens, symptomatic treatment, and allergen immunotherapy.6-8

  • Check local pollen counts daily and limit time outside when pollen counts are high. Rain helps clear pollen from the air, so the best time to go outside is after a good rain.
  • Delegate outdoor chores whenever possible and wear a pollen mask if you must do outside tasks. 
  • Keep windows closed and use air conditioning instead.
  • Wash bedding at least once a week in hot, soapy water.
  • Wash your clothes after outdoor activities and dry all clothes in a dryer as opposed to line drying outdoors.
  • Bathe and wash your hair every day before bedtime to keep pollen out of your bed.
  • Wipe off any pets to remove pollen before letting them into your home.
  • Ensure everyone removes their shoes before entering your home.
  • Use certified asthma and allergy air filters.
  • Pharmacological treatment, including antihistamines, corticosteroids, decongestants, and saline douches.
  • Allergen immunotherapy as directed by your healthcare provider.

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Common Pigweed Allergen Facts, Symptoms, and Treatment

Common Symptoms

Common pigweed allergy symptoms can be similar to many other pollen allergies and may include:3,6

  • Sneezing
  • Nasal congestion
  • Runny nose
  • Watery eyes
  • Itchy throat and eyes
  • Wheezing

If you're sensitized to common pigweed and have asthma, the weed pollen may trigger or worsen asthma symptoms, such as coughing and wheezing.3,6

How do I know if I'm allergic?*

Together with your symptom history, skin-prick testing or specific IgE blood testing can help determine if you are sensitized to a particular allergen. If you are diagnosed with an allergy, your healthcare provider will work with you to create a management plan.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

Pollen Season

While some weed species are insect-pollinated and others are wind-pollinated, common pigweed pollinates in the summer and fall.1,4

  1. Steinman H. Weed pollens. Allergy Resources International. 2009. Available from: http://www.immunocapexplorer.com/uploads/cms/asset_brick/asset/10415/52-5107-92_02-Weed_pollens.pdf.
  2. CABI Invasive Species Compendium.|place unknown|:CABI, 2019 Nov 22. Available from: https://www.cabi.org/isc/datasheet/4652.
  3. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014 [2018 Apr 23]. Available from: https://acaai.org/allergies/types/pollen-allergy.
  4. Pollen.com [Internet]. Plymouth Meeting, PA: IQVIA Inc.; 2020. Available from: https://www.pollen.com/research/genus/amaranthus.
  5. EAACI, et al. Molecular allergology user's guide. Pediatr Allergy Immunol. 2016 May;27 Suppl 23:1-250. doi: 10.1111/pai.12563. PMID: 27288833. Available from: http://www.eaaci.org/documents/Molecular_Allergology-web.pdf.
  6. Roberts, G., Xatzipsalti, M., Borrego, L., Custovic, A., Halken, S., Hellings, P., Papadopoulos, N., Rotiroti, G., Scadding, G., Timmermans, F., Valovirta, E. Paediatric rhinitis: Position paper of the European Academy of Allergy and Clinical Immunology. Allergy. 2013 Sep;68(9):1102-16.
  7. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2019 Apr 9. Available from: https://community.aafa.org/blog/tips-for-preventing-allergic-reactions-to-tree-and-grass-pollen.
  8. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2020 Apr 16. Available from: https://www.mayoclinic.org/diseases-conditions/hay-fever/in-depth/seasonal-allergies/art-20048343.
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