How often do you replace your pillow with a new one? If you’re allergic to dust mites, those microscopic creatures that live in pillows, mattresses, sofas and clothing, you should change your pillow every two years or at least put a barrier between you and the pesky mites with allergy-proof pillow covers, says Linda B. Ford, MD, medical director of the Asthma and Allergy Center in Papillion, NE. You can also wash your pillow weekly in hot water (around 120F) or stick it in the freezer, since these little pests can’t live in extreme temps. If you’re not allergic to dust mites, you probably needn’t bother—unless you want to be extra protective when it comes to what you put your head on every night.