How often should you actually wash your pillows?

Before the interval, a more urgent question: can yours go in the machine at all? For a great many pillows the answer is no, and washing one that cannot be washed does more damage in an hour than never washing it would do in a decade.

The statistics are not real

It is worth dealing with these first, because they are what sends people to the machine in a hurry. You will have met at least one of them. That a pillow doubles in weight over its life from dust mites and their droppings. That a third of the weight of an old pillow is mites. That a two-year-old pillow is ten per cent dead insect.

Nobody has been able to find the study. The doubling claim, which is usually told about mattresses and gets borrowed for pillows, traces to a single newspaper article in 2000 quoting a researcher, and both Snopes and Live Science have gone looking for the underlying work and come back with nothing. The trade body for the industry it flatters says it is aware of no scientific study supporting it. The other figures are the same story with different arithmetic: repeated everywhere, sourced nowhere.

A number that everyone quotes and nobody can source is not a finding. It is a rumour with a decimal point.

What is true is duller and more useful. You shed skin and sweat all night, some of it goes through the pillowcase into the pillow, and dust mites eat it and like the humidity. If you are allergic to them that matters and it is worth being strict, and washing warm rather than cool is the part that helps. If you are not, this is housekeeping rather than health, which is where the bedsheets answer lands too, and a pillow is not a health emergency waiting to happen just because somebody put a percentage on it.

Which pillows can actually be washed

This is the part that decides everything else, and it is on a label almost nobody has read since the day the pillow arrived.

Polyester and microfibre pillows are the easy case and the most common. Warm water, a gentle cycle, a small amount of mild detergent. Two at a time keeps the drum balanced.

Down and feather pillows are washable and are where most people go wrong, not in the washing but afterwards. Wet down clumps, and down that is put back on a bed while it is still damp in the middle goes musty and stays that way.

Solid memory foam and latex cannot be machine washed and should not be submerged at all. Foam that has been soaked cracks and breaks down, and a memory foam pillow that has been through a wash cycle comes out heavy, misshapen and structurally finished. This is the single most consequential thing on this page, and it is why the answer in our schedule carries its caveat in the answer itself rather than in the note underneath, where a phone would have hidden it.

Shredded memory foam is the confusing middle. The cover usually comes off and washes; the filling usually does not. Check before you assume it behaves like the solid kind or like a polyester one, because it looks like the first and feels like the second.

What to do with the ones you cannot wash

Spot clean marks with a cloth, mild detergent and as little water as will do the job, then let it dry completely before it goes near a bed. For the general staleness that makes people want to wash a pillow in the first place, sprinkle it with bicarbonate of soda, leave it for an hour or two, and vacuum it off. And air it: a few hours somewhere with moving air does more for a foam pillow than anything else available to it.

None of that is as satisfying as a wash cycle. It is, however, the difference between having the pillow next year and not.

The drying is the dangerous part

For the pillows that can be washed, this is where the real failure happens, and it is the same failure as towels with the stakes raised. A pillow holds a great deal of water in a place you cannot see, and the outside will feel dry long before the core is. Put it back on the bed at that point and you have sealed damp into the middle of something you press your face into for eight hours a night.

So allow much longer than seems reasonable, and check by squeezing the centre rather than the surface. If it feels cool in the middle, it is not dry. Dryer balls or a couple of clean tennis balls help by breaking up the clumps as it tumbles, and a second drying cycle on a pillow you were sure was finished is the cheapest insurance in this article.

The thing that makes most of this unnecessary

A zipped pillow protector, underneath the pillowcase. It costs very little, it goes in with the sheets, and it means that almost everything described above never reaches the pillow at all. It also works on the pillows that cannot be washed, which is precisely where it is worth most, because it is the only way to keep a memory foam pillow clean without ever getting it wet.

This is the pillow version of what this guide keeps finding: the cheap unglamorous habit outperforms the wash, and nobody mentions it because there is very little to sell in a zip.

One thing we are not going to tell you

When to replace it. There are sourced figures for pillow lifespan and we have read them, but this is a wash schedule, replacement is a different question, and it is the only advice on this page that would amount to suggesting you buy something. It costs us nothing to leave out, and a page whose whole authority rests on not appearing to want anything should probably keep it that way.