Ingrown hairs are not pretty. But, chances are, if you're a regular shaver or waxer (guys, this goes for you, too) you've had to deal with them at one time or another.
Essentially, an ingrown hair is when a hair penetrates your skin and your skin reacts to it as it would to a foreign body, becoming inflamed.
"When a hair is trying to get out of the skin, they tend to get a bit lost sometimes," Assoc. Prof. Greg Goodman of the Dermatology Institute of Victoria told The Huffington Post Australia. "They can go sideways and in doing that, become a foreign body.
"The behaviour is not like a hair should be behaving, in which it tries to grow out of the hair follicle, and as such your skin reacts by becoming inflamed and trying to get rid of it, much like it would a pimple."
The result is a gross, pimply type of inflammation we won't actually display here, but invite you to Google Image Search if you dare.
"More often than not, an ingrown hair is a reaction to what you're doing," Goodman said. "So if you are shaving and trying to shave too close, you are getting a retraction into the hair follicle.
"Waxing will yank the hair out, and if the hair doesn't come out, it will shrivel into a million pieces, retract back into the hair follicle and cause inflammation.
"Those who use heavy moisturisers against the grain of the hair might also find they inflame the hair follicles.
"It tends to be more common in certain hair types, so, for instance, those with really thick hair are more likely to get them. Fine, wispy-hair people shouldn't have as much of a problem.
"It's also much more potent in younger people, as their inflammatory responses tend to be brisker."
How to avoid
In most cases, ingrown hairs can be avoided simply by changing your hair removal processes.
"If you're fortunate enough to have dark hairs, hair removing treatments like lasers are the best, and they target dark hair especially well," Goodman said.
"Among those, usually the longest wavelength lasers are better than short wavelength and IPL.
"The thing is, you don't have to remove the hair totally. So for example, for males, just a couple of treatments will weaken the hair and make it softer and more pliable, which in turn, decreases the potential for inflammation.
"Other good options are depilatory creams rather than waxing, which [should be avoided], because really, you don't want the situation whereby you are pulling on hairs and getting that reaction. Depilatory creams are much kinder, as far as ingrown hairs go."
For guys who are regular shavers, Goodman advises against shaving too close to the skin (so yes, that means those multi-razor razor blades are probably not the best choice for you).
"If you use a multi-blade razor, it's more likely your hair will retract under the skin and become inflamed. You should actually avoid shaving really closely.
"You also want to shave with the grain of the hair, not against."
Another neat trick is to use hair conditioner instead of a shaving cream.
"It softens the hair considerably," Goodman said. "And is unlikely to leave such a rigid edge, making things more viable."
If, despite your best efforts, you still end up with a juicy, painful ingrown, Goodman suggests trying a hydrocortisone cream. Some of these can be purchased over-the-counter, while others, such as Goodman's personal recommendation Advantan, require a prescription.
And as for that age-old question, "to squeeze, or not to squeeze", Goodman's answer might surprise you.
"If you squeeze it and it's not ready to go anywhere, you're really not helping. In fact, you'll probably give yourself a really good blind pimple," Goodman said.
"But if you know you can get it out -- if you can see it's a little pustule you are able to easily release -- then it's fine.
"In saying that, don't get your scalpel out and try it do it yourself at home. Seriously. You'll be surprised at what people do."
If left untreated...
... an ingrown hair will not keep on growing forever and ever. But, according to Goodman, "they can get pretty large."
"I have certainly extracted hairs which have been three or four centimetres long, which have looked almost like a worm. They can go a long way, growing sideways under the surface," he said.
"How long they get really depends on what type of hair we're talking about. So, a beard hair has a much longer growth cycle than, say, a leg hair, which don't grow as long."
Generally, Goodman advises a 'wait-and-see' approach when it comes to dealing with an ingrown, as often things will resolve themselves.
"But if, after a couple of weeks, you have a lump sitting there there and it's not going away, you may have developed a cyst, which you may need looked at by a health professional," he said.
"Normally, however, these things do tend to resolve themselves."