Grass pollen allergy

What it is

Plants release tiny pollen grains to fertilize other plants of the same species.² Grass pollen is scattered by the wind rather than carried by insects, which makes it easy to breathe in.¹ There are hundreds of kinds of grass, but only a few cause allergy symptoms.²

AAAAI sorts the grasses that matter into two large classes, northern and southern. Its grass allergy page lists timothy, Kentucky blue, Johnson, rye and fescue as common northern grasses, and Bermuda and Bahia as common southern grasses.¹ A 2025 AAAAI work group report groups Johnson grass differently. It counts Johnson and Bermuda grass among the warm-climate grasses that are still considered southern, and says both have been spreading north.³

The split also shows up in botany. The northern pasture grasses belong to the subfamily Pooideae, which does best where temperatures are lower and water is plentiful.³ Bermuda grass belongs to a second subfamily (Chloridoideae), and Bahia and Johnson grass to a third (Panicoideae).⁴ Their pollen allergens differ. One highly allergenic group of temperate grass pollen allergens, known as group 5, does not occur in subtropical grass pollen.⁴

Symptoms it causes

Grass pollen causes symptoms mainly when it is breathed in. In the nose, it can cause sneezing, a runny or stuffy nose, an itchy nose and facial pressure. In the eyes, it can cause itching, redness and watering.¹ In people with asthma, it can bring on coughing, wheezing, chest tightness or congestion, and shortness of breath.¹

Touching grass can raise red, itchy welts (hives) in some people, usually after direct contact. This is much less common than nose and eye symptoms, and hives have many other causes.¹

Grass pollen can also cause symptoms through food. Some people with grass pollen allergy notice an itchy or swollen mouth, lips, tongue or throat after eating certain raw fruits and vegetables, including peaches, celery, tomatoes, melons and oranges.⁵ These reactions usually stay in the mouth and fade quickly once the food is swallowed or removed.⁶

Where and when it grows

In most regions of the US, grasses pollinate in late spring, from about April through early June.¹ Grasses cause most of the pollen allergy symptoms of late spring and summer, and where you live can affect when you have symptoms. In warmer areas, including California, Texas and the South, grass pollen can be found year-round.²

Florida shows how long the southern season can be. There, grasses pollinate in spring, summer and fall, and Bermuda grass pollinates year-round in the subtropical parts of the state.⁷ University of Florida extension puts Bahia grass, the most abundant grass in Florida, high on its list of allergenic plants.⁷

The line between north and south is moving. An AAAAI work group reports that Johnson and Bermuda grass have been expanding steadily northward, and that allergists should now consider testing for them in most of the US, except possibly the northern Midwest.³ Long-term pollen records in North America have also generally shown seasons starting earlier and lasting longer.³