Johnson Grass
Allergy Facts, Symptoms, and Treatment

Johnson grass is known by myriad names, such as Aleppo grass, Arabian millet, Egyptian millet, evergreen millet, false guinea, Morocco millet, and Syrian grass.¹ A fast-growing perennial that can reach heights of approximately 2.1 meters (7 feet), Johnson grass is also an extremely invasive grass with worldwide distribution.^1,2 While grass pollen can trigger or worsen asthma symptoms, those sensitized to Johnson grass also may have symptoms of allergic rhinitis (hay fever), which affects the eyes, nose, and throat.³ Johnson grass releases an abundance of wind-borne pollen.⁴ Although pollen season can vary year to year due to climatic-factor fluctuations, the highest concentration of grass pollen usually appears one to two months after the start of the main flowering season.⁵ With moderate allergenicity, Johnson grass pollination persists throughout the year but peaks from early summer through fall.^6,7

Are there other allergens I could be sensitized to?*

Many patients with Johnson grass 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.¹⁰ Other respiratory allergens that may cause reactions associated with Johnson grass are other grasses, including wheat, along with tree and weed pollens.¹⁰

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.¹¹ Common plant foods involved in OAS for Johnson grass include melon, watermelon, citrus, banana, pineapple, persimmon, zucchini, tomato, hazelnut, peanut, and many more.¹⁰

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.¹⁰

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.¹⁰

nCyn d 1 

• Indicates that the symptoms are caused by pollen of Johnson grass and related species.¹⁰
• Grass pollen immunotherapy may be an option.¹⁰

rPhl p 7

• Indicates symptoms may be caused by grass or by other pollen, e.g., from trees and weeds. Further investigation may be considered to confirm all allergy triggers.¹⁰
• May be associated with more severe symptoms and higher prevalence of asthma than other grass pollen allergies.¹⁰

rPhl p 12

• Indicates that symptoms may be caused by grass or by other pollen, e.g., from trees and weeds.¹⁰
• May be associated with PFAS after ingestion of fruit and vegetables, e.g., melon, tomato, apple, and celery. Further examination is recommended.¹⁰

MUXF3 (CCD)

• Positive specific IgE for Johnsson grass 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.¹⁰

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.