Quick Answer
Grass pollen allergy is the most common cause of summer allergic rhinitis globally. Grasses like Timothy, Kentucky bluegrass, and Bermuda grass release airborne pollen from May through July in northern regions. Grass allergens are highly cross-reactive — if you are allergic to one grass, you are likely allergic to most. FDA-approved sublingual tablets and allergy shots are highly effective treatments.
Major Grass Pollen Allergens
The grasses most responsible for summer allergic rhinitis in the US include Timothy grass (Phleum pratense), Kentucky bluegrass, orchard grass, perennial ryegrass, and sweet vernal grass. These cool-season grasses are members of the Pooideae subfamily and share highly cross-reactive allergen proteins, particularly the major Phl p 1 and Phl p 5 allergens of Timothy grass.
Bermuda grass (Cynodon dactylon) is the dominant warm-season grass allergen in the South, Southwest, and along the Gulf Coast, where it produces pollen from March through October. Bermuda grass has less cross-reactivity with cool-season grasses and requires separate skin testing and consideration for immunotherapy.
Cross-Reactivity Among Grasses and Oral Allergy Syndrome
Cool-season grasses share group 1 and group 5 allergen proteins, producing very high cross-reactivity. Patients sensitized to Timothy grass are almost always sensitized to Kentucky bluegrass, ryegrass, and orchard grass. This cross-reactivity is the basis for FDA-approved grass pollen sublingual tablets: Grastek (Timothy grass) and Oralair (5-grass mixture) provide broad protection against most cool-season grasses.
Grass pollen allergy is associated with pollen-food allergy syndrome: patients may develop oral tingling or itching from raw tomatoes, oranges, peaches, celery, and wheat due to cross-reactive proteins. These reactions are mild and confined to the mouth and throat; cooking destroys the cross-reactive proteins and makes these foods safe to eat in cooked forms.
Treatment: Immunotherapy Options
Grass pollen allergy responds well to both subcutaneous immunotherapy (allergy shots) and sublingual immunotherapy. Two FDA-approved sublingual tablets are available: Grastek (Timothy grass, FDA-approved 2014) and Oralair (5-grass mixture: sweet vernal, orchard, perennial ryegrass, Timothy, and Kentucky bluegrass, FDA-approved 2014). Both are taken once daily, with treatment beginning 16 weeks before grass pollen season for full benefit.
Standard allergy shots with grass pollen extracts are also highly effective. Both SLIT tablets and SCIT shots produce sustained symptom reduction after 3–5 years of treatment. Medication management during season includes nasal corticosteroid sprays, antihistamines, and leukotriene inhibitors as adjunctive therapy during high-exposure periods.
Key Takeaways
- Timothy, Kentucky bluegrass, and orchard grass are the major cool-season allergy culprits — highly cross-reactive.
- Bermuda grass is the dominant warm-season grass allergen in the South — separately tested and treated.
- Two FDA-approved grass pollen SLIT tablets: Grastek (Timothy) and Oralair (5-grass).
- Grass pollen cross-reacts with raw tomatoes, peaches, oranges, and celery via shared profilin proteins.
- Start preventive SLIT tablets or nasal steroids 12–16 weeks before grass season begins for full effect.
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