Why Pillows Turn Yellow and How to Clean Them

Place pillows in the dryer on low heat. Add a few dryer balls or clean tennis balls to keep the filling from clumping. Down may take longer to dry, which is normal, Roberts says. To reduce static, a dryer sheet works well. And triple-check that pillows are completely dry (so there’s no mold!) before making the bed.

Clean pillows by hand if you cannot use a washing machine.

If you can’t find the tag on your pillow, you can always wash it the old-fashioned way. Wait for a sunny day and take the pillows outside and whack them with a clean broom handle (or a carpet paddle if you have one like your great-grandmother had!). Then, let them air out outside for a few hours. For foam cushions, you can take out your vacuum cleaner and use the upholstery brush attachment.
Use pillow protectors.

Cover pillows with pillow protectors before putting on pillowcases. Then, wash them every week when you wash your bedding.
Relax daily.

Fluff your pillows between washes if you make the bed every day. This helps keep them plump and redistributes the filling to restore its shape, Roberts says.
Have extra pillows ready.