Ingrown hairs are hairs that have curled round and grown back into the skin.
They produce raised red spots, which can sometimes become infected and turn into painful pus-filled sores.
Ingrown hairs can be itchy and embarrassing, but they often go away on their own without having to do anything.
Anyone can get them, but they tend to be more of a problem in people with curly or coarse hair.
What causes them?
Ingrown hairs have usually grown out of the skin, curled back round and re-entered the skin. Some curl back into the follicle without even exiting the skin.
It can happen when the hair follicle becomes clogged with dead skin cells. This forces the hair inside it to grow sideways, which is much more likely to happen if the hair is already curly or coarse, and if you've recently shaved the hair.
Ingrown hairs are particularly a problem where you shave – the beard area in men, and the legs, armpits and pubic area in women – because the hair that grows back has a sharper edge and can easily poke back into the skin.
They show up like pimples in the skin, and sometimes you can see the hair trapped beneath the skin. The spots can be filled with pus.
What should I do?
Don't pick or scratch at the ingrown hair, as bacteria can enter the small wound this creates, increasing your risk of infection. You might also be left with a scar.
Squeezing the spots can also damage the skin and cause infection.
If you must, use a sterile needle or set of tweezers to gently tease the hair out of the skin if it's near the surface. Don't dig for it if the hair lies deep.
But if you can, leave the ingrown hairs for a while as they may go away without having to do anything.
Men who are prone to ingrown hairs around their face may find it best to grow out their beard – longer hairs aren't as sharp at the ends, so are less likely to become ingrown.
What if there are lots of pus-filled spots?
The hair follicles of ingrown hairs can sometimes become infected and inflamed, which is known as folliculitis.
The hair follicles will swell into pus-filled spots (although note that pus doesn't always indicate infection).
Again, mild cases of folliculitis often clear up without treatment, so try stopping shaving for a few days and see if it gets better.
You could also try dabbing mild antiseptic such as tea tree oil.
If the spots don't improve and are bothering you, see your GP. If one particular spot is a problem, your GP may be able to release the hair using a sterile needle.
You would generally only need antibiotics if the skin is severely infected, with pustules and abscesses.
Preventing ingrown hairs
The simplest way to prevent ingrowing hairs is to let your hair grow freely without shaving it. You may want to try this for a brief period, for relief from particularly bad spots.
If you don't want to stop shaving, try the following shaving tips:
use a sharp, single-bladed razor
wet your skin with warm water and use a gel
shave in the direction the hairs are growing
use as few strokes of the razor as possible
rinse the razor after every stroke
try not to shave too closely – leave a bit of stubble if you can (as bacteria can enter the tiny openings of freshly shaved skin)
Other hair-removal methods may be less likely to result in ingrowing hairs. For example, instead of shaving legs, you may want to try depilatory creams, electrolysis or laser removal.
Is it just an ingrown hair, or something else?
There are many skin conditions that can easily be mistaken for ingrown hairs, including:
keratosis pilaris("chicken skin") – a common and harmless condition where the skin becomes rough and bumpy, as if covered in permanent goose pimples
a cyst or abscess
impetigo,a highly contagious skin infection that mainly affects children
heat rash (prickly heat)
molluscum contagiosum,a highly contagious viral infection that affects the skin
If you're unsure, see your GP. The above links will take you to more information on these similar looking skin conditions.