Pollen allergies, also known as hay fever or allergic rhinitis, occur when the immune system overreacts to pollen from trees, grasses, and weeds. When pollen enters the body, it can trigger symptoms like sneezing, runny nose, itchy eyes, and congestion. These reactions happen because the body mistakenly identifies pollen as a harmful substance. The severity of pollen allergies can vary depending on the type of pollen and the individual's sensitivity. Common pollen sources include tree pollen in spring, grass pollen in late spring and summer, and weed pollen in late summer and fall. Managing symptoms often involves avoiding exposure and using medications like antihistamines.