Allergen Fact Sheets

Ryegrass Allergen Facts, Symptoms, and Treatment

Grass Pollen
Grass Pollen
Allergy Insider


Native to Europe but introduced on all continents with temperate zones, ryegrass is a short-lived perennial, biennial, or annual bunchgrass.1 Also known as ray-grass, English ryegrass, perennial ryegrass, and Italian ryegrass, it's typically found in locales such as pastures, footpaths, sand dunes, and riverbeds.1,2 Ryegrass is wind-pollinated, and it releases an abundance of pollen during peak flowering season.3 Flowers are located on stalks that are 5 to 15 centimeters (2 to 6 inches) tall, and pollination occurs from spring to fall.4 Ryegrass is severely allergenic and is one of the most serious of a large number of grasses that cause allergic rhinitis (hay fever) and other respiratory allergies in humans.2,4

Where is ryegrass found?

While native to Europe, ryegrass can be found on all continents with temperate zones.1 It's typically situated in locales such as pastures, footpaths, waste places, sand dunes, river beds, and roadsides.2

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Are there other allergens I could be sensitized to?*

Many patients with ryegrass 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.7 Other respiratory allergens that may cause reactions associated with ryegrass are other grasses, including wheat, along with tree and weed pollens.7

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.8 Common plant foods involved in OAS for ryegrass include melon, watermelon, citrus, banana, pineapple, persimmon, zucchini, tomato, hazelnut, peanut, and many more.7

Knowing the proteins, or components, within each allergen that are triggering your symptoms can help guide your management plan. With that in mind, and based on your symptom history, your healthcare provider may suggest something called a specific IgE component test, which can help reveal other pollens and foods you may react to. Results from this test can also help your healthcare provider decide if allergen immunotherapy may reduce your symptoms.7

Already have your specific IgE component test results?

Your component test results will include the name of the components (a series of letters and numbers). Your healthcare provider will likely review the results with you, but here you'll find an at-a-glance breakdown you can use as a reference. Simply match the component names to the list below to see what they mean in terms of symptom management.7

rPhl p 1, rPhl 5b   

  • Indicates that the symptoms may be caused by grass pollen.7
  • Grass pollen immunotherapy may be an option. 7

rPhl p 7

  • Indicates symptoms may be caused by grass or by other pollen, e.g., from trees and weeds. Further examination may be considered to confirm all allergy triggers.7
  • May be associated with more severe symptoms and higher prevalence of asthma than other grass pollen allergies.7

rPhl p 12

  • Indicates that symptoms may be caused by grass or by other pollen, e.g., from trees and weeds.7
  • May be associated with PFAS after ingestion of fruit and vegetables, e.g., melon, tomato, apple, and celery. Further examination may be considered.7


  • Positive specific IgE for ryegrass in combination with MUXF3 CCD (Cross-Reactive Carbohydrate Determinant) being the only positive component test indicates that the cause of symptoms may be something other than grass pollen.7

Test results should be interpreted by your healthcare provider in the context of your clinical history. Final diagnosis and decision on further management is made by your healthcare provider.

*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.8,10,11

  • 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.

Looking for more allergy info and management tips?

Visit the Living with Allergies section

Common Symptoms

Ryegrass allergy symptoms can be similar to many other pollen allergies and may include:5,8

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

If you're sensitized to ryegrass and have asthma, grass pollen may trigger or worsen asthma symptoms, such as coughing and wheezing.5,8

While symptoms are usually limited to the throat, nose, and eyes, some people who are severely allergic to grass may also develop hives (urticaria) upon contact with its pollen.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 ryegrass may flower almost all summer, it usually pollinates between May and July in the Northern Hemisphere.1

Is there a risk for a severe event?

Responses close to anaphylaxis have occurred in the most dangerous reaction cases.5 Plus, anaphylaxis has been reported in cases where abraded skin contacted allergenic grass.10

  1. Steinman H, Ruden S. Grass pollens. Allergy Resources International. 2004. [2007]. Available from:
  2. Popay I.CABI Invasive Species Compendium.|place unknown|:CABI, 2013 Aug 11. Available from:
  3. Gangl K, Niederberger V, Valenta R. Multiple grass mixes as opposed to single grasses for allergen immunotherapy in allergic rhinitis. Clin Exp Allergy. 2013 Nov;43(11):1202-16. doi: 10.1111/cea.12128. PMID: 24152153; PMCID: PMC6624134.
  4. [Internet]. Plymouth Meeting, PA: IQVIA Inc.; 2020. Available from:
  5. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014 [2018 Apr 23]. Available from:
  6. Gagne, C. When grass allergy attacks: From symptoms to managing. Allergic Living. 2020. Available from:
  7. 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:
  8. 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.
  9. Tsunoda, K., Ninomiya, K., Hozaki, F. and Kaga, K. (2003), Anaphylaxis in a child playing in tall grass. Allergy, 58: 955-956. doi:10.1034/j.1398-9995.2003.00121.x. Available from:
  10. Asthma and Allergy Foundation of America [Internet]. Arlington, VA: Asthma and Allergy Foundation of America; 2019 Apr 9. Available from:
  11. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2020 Apr 16. Available from: