system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do ingrown hairs get infected even if the surface of skin isn't broken?

If the skin isn't broken bacterial shouldn't be able to make it's way in right? But somehow they still get infected.
gpt
In fact they dont.
Ingrown hairs simply are seen as forein object and thus needed to be isolated and/or eliminated. This is one of the jobs of our white blood cells.
Sadly most of these cells have a very short lifespan (around 2 days) and when their "corpses" accumulate they create pus.
Inflammation appears whenever our white blood cells discover something "not right": it is like ringing a local alarm, while pus appears when lots of white cells, called by the alarm, gather for a long time and then die in the area.
So, while these mechanisms do appear durning infections, it doesnt mean that when they do there is an actual infection. Simply this time the foreign object instead of being a bacteria is a looong string of chitin (the hair).
The white cells continue to attack it trying to remove it and in the end just die around it. (They dont know that they are doing an useless/harmful work, they just react as programmed)