A mattress protector should generally be washed every 1 to 2 months to maintain cleanliness and hygiene. If there is a spill, stain, or if the user suffers from allergies, it is recommended to wash it more frequently, even as often as every 2 weeks for allergy sufferers. For guest beds, washing quarterly might suffice. Washing immediately after any spills or illness is also advised to prevent stains and bacteria growth. Air drying or using low heat for drying is recommended to preserve the protector’s protective materials and fit.