The Presence of Pus in a Pimple, Pustule or Wound: What is it and What Does it Mean?

Whether being squirted through a zit, or oozing out of a wound, most of us have had some contact with pus. We may turn our nose up or balk at the sight of this yellowish-white viscous fluid, but it’s actually doing us some good.

When your body comes under attack from bacteria the first wave of immune cells to leap to your defence are neutrophils. These are white blood cells that are drawn to the sites of infection by a process known as chemotaxis. They are fast acting and engulf the invader. This finishes off the bacteria, but it also deals a deathblow to the neutrophils as they are killed in the process.

The body needs to get rid of all this debris, and that’s what pus is. The fluid contains dead neutrophils and the remains of pathogens, some dead skin cells and still struggling bacteria that haven't yet given up the fight.

Pus does need to leave the body as a build up can be toxic. There is usually no problem with ignoring the small amount of pus in pimples. If you are tempted to squeeze, doctors recommend you should wash your hands afterwards. That's because the pus could still contain live bacteria that could be spread to other parts of the body if you haven’t got rid of it all from your fingertips.

Now a pus-filled pimple is not going to win any beauty awards, but the really good thing about them is that they are telling you that your body is in good working order and up to the job of fighting infections.

But, if a wound gets bigger and the amount of pus increases, it’s a sign that the body hasn’t yet won its battle against the bugs - and may need some help from a course of antibiotics. If there is a large amount of pus pouring from a wound, and that wound feels hot to the touch, there could be something more serious going on, and medical help and advice should be sought.

It was pus that gave science, and in particular a Swiss physician, one of the most important discoveries ever - DNA. In 1869 Frederick Miescher discovered the genetic material whilst studying leukocytes from pus-ridden bandages. He called the substance ‘nuclein’ because it came from the nucleus.