Pollen allergy, also known as hay fever or allergic rhinitis, occurs when the immune system overreacts to pollen from trees, grasses, and weeds. Symptoms can include sneezing, runny nose, itchy eyes, and congestion. These reactions happen when pollen particles enter the body and trigger an immune response. The severity of pollen allergies can vary depending on the type of pollen and the time of year. For example, tree pollen is more common in spring, while grass pollen peaks in late spring and early summer. Managing symptoms often involves avoiding exposure and using medications like antihistamines.