Pollen allergies are your body's misidentification of certain airborne substances. When plants release their pollen into the air to fertilize each other and any of those pollens reach your nose, eyes or mouth, your body kicks into action. An antibody called immunoglobulin E seeks out the invading allergens and then delivers them to your mast cells so that they can be neutralized. One of the chemicals released in the process is called histamine, and histamine is responsible for your cold-like allergy symptoms, including a runny nose, congestion, sneezing and itchy, watery eyes.

Pollen allergies most commonly develop during childhood and early adulthood. As you get older, the symptoms tend to gradually subside. But while your hay fever is at its height, it will last as long as the pollen you're allergic to is in the air. For people allergic to tree pollen, hay fever is most common in the spring. For those allergic to grass pollen, symptoms tend to be at their worst in the late spring and summer. If you're allergic to weed pollen, your hay fever will be strongest in the fall. If you're allergic to grass, tree and weed pollen, you'll suffer from spring to fall.

While pollen allergies last, you can treat the symptoms to make the season more bearable. The three most common treatments for pollen allergies are antihistamines, decongestants and nasal steroids. The antihistamines work to block the histamine that your immune system produces so that you don't feel its effects of itching, sneezing and a runny nose. They're available both over-the-counter and by prescription. Meanwhile, decongestants are effective at clearing up a stuffy nose and enabling better breathing, but you can only take them for a few days at a time. Nasal steroids relieve the inflammation -- and runny nose -- caused by allergies.