Quick Care strongly advises that you consult a physician if you're not sure whether your symptoms are allergic, or if non-prescription treatment doesn't work well. Many more prescription options exist beyond the products recommended here. Allergies are simply your body's immune system making a big deal out of nothing. Unfortunately, this just causes you harm, and doesn't hurt the pollen or mold in the least. When histamine is released it causes swelling, itching, and mucus production.
Some chemicals released by the mast cells attract other immune cells.
These other cells also release damaging substances, which continue the allergic symptoms for hours or days. Why this over-reaction of the immune system occurs at all is still a mystery. In the U.S., allergy rates peak when people are in their teens through thirties, then become less and less common as they age. This bring us to the next point. The chart below helps, but sometimes even doctors can't tell for sure.