Those yellow spots on the pillows may be disgusting, but they are not permanent.

Although we know that the human body – including our own – can sometimes be disgusting, we prefer not to remember it. So when you change your sheets and find that your once perfectly white pillows are now covered in a web of yellow and brown stains, it can be unsettling.

But these discoloured pillows look worse than they really are. There is a reasonable explanation for the origin of these stains, and they can be removed. Here’s what you need to know.