Wash your protector according to the wash care instructions. Since a fitted sheet is washed every one to two weeks and is placed on top of the protector, it only needs to be cleaned every 1-2 months (depending on soil level). If you tend to sweat, have pets, or extreme allergies, you may choose to wash your protector more often than recommended. Do not bleach, iron or dry clean.
Remember, after an illness, it's important to remember to clean your mattress protector, along with all of your other bedding. If you are using your protector in a guest room that is not being used regularly, wash before you have a guest or at least every 3-4 months to keep it dust-free.