That's good news for people who can control their triggers. The two most common outdoor allergens are pollens and molds. The most common indoor allergens are cat and dog dander, cockroaches, indoor molds, and dust mites, which are found in bedding and upholstery. It's relatively easy to avoid outdoor allergens. Pollens are most plentiful in the spring, so staying indoors and keeping windows closed will keep them out.
Molds are often plentiful in the fall.
As for indoor allergens, dust mites are the most common. They tend to hang out in bedding, so encasing beds and pillows in hypoallergenic coverings will reduce your exposure. Removing carpets, drapes and other furnishings that gather dust will further reduce the amount of dust you're exposed to. Most experts recommend washing bedclothes once a week. Because dust mites thrive in humid environments, using a dehumidifier to bring the humidity in your house to under 50 percent may also help.