Rye Grass: A Cool Season Grass Causing Allergies in Warmer Months

Written by Dr. Joel Gallagher, Allergy and Asthma Center of NC, Cone Health Medical Group and Dr. Peter Gallagher, PhD Professor Emeritus, College of Applied & Natural Sciences at Louisiana Tech University 

Rye grass (Lolium species) is a cool season type of turf grass (along with fescue, Kentucky bluegrass, and other grass varieties) as opposed to the warm season grasses such as Bermuda grass, St. Augustine, Zoysia, and centipede. North Carolina is in a transitional zone where a combination of warm season and cool season grasses are often used. In the Piedmont Triad, rye grass seed is often mixed with other grass species either for faster coverage (especially with autumn planting) or overseeded for winter color (when the warm weather grasses are brown while they are dormant).

Image of perennial ryegrass (Lolium perenne). "perennial ryegrass Lolium perenne" by loarie is licensed under CC BY 2.0.

Rye grass is a common source of seasonal allergies due to the large amount of pollen released during the peak flowering season. This pollen can cause allergic rhinitis (hay fever) and other respiratory allergies, including allergic asthma. It's a common seasonal allergy, especially during the spring and summer months when rye grass is in bloom. Rye grass is wind-pollinated and releases a significant amount of pollen during its flowering season. Symptoms can include sneezing, runny nose, watery eyes, and itching, but can also affect the respiratory system. Many people with rye grass allergies can also experience symptoms when exposed to other grass, tree, or weed pollens due to cross-reactivity. To reduce exposure, individuals can consider staying indoors, keeping windows closed, using air conditioning, and washing bedding regularly.

We often get asked about rye allergies – especially when we see patients reporting a gluten allergy. This is typically in the setting of concern for a rye cereal grain allergy. The gluten-containing grains include wheat, of course, but also rye, barley, and triticale, which is a cross-species between wheat and rye. Other wheat varieties that include gluten are wheatberries, durum, emmer, semolina, spelt, farina, and farro. Many people confuse rye allergy with gluten sensitivity or celiac disease, but they are not the same. A rye allergy specifically involves the immune system reacting to proteins in rye – Lolium species (in the case of the turf grass) or Secale species (in the case of the cereal grain). Celiac disease, on the other hand, is an autoimmune condition where gluten triggers an autoimmune response that damages the small intestine and can lead to other clinical symptoms including rashes. Gluten sensitivity/intolerance relates to difficulties digesting gluten, a protein found in rye, wheat, barley, and other grains. Gluten sensitivity/intolerance does not trigger an immune response like celiac disease or rye allergy.

The rye that we test for during environmental allergy testing is the Lolium species, whereas rye that is used for human consumption is Secale species. While cross-reactivity can occur, most individuals can tolerate gluten without a problem, even if they are allergic to rye grass. So–even if you had spring and summer grass allergies—continue to enjoy those carbs!