What are ingrown hairs?

Ingrown hairs are hairs that have grown back into the skin instead of straight up, according to WebMD. While an ingrown hair is not serious, it can cause irritation at the site.

Sometimes, dead skin may block a hair follicle, causing it to curl around backwards, according to WebMD. These hairs can cause painful bumps, or, in some cases, a spot of irritation that resembles a small boil. Most ingrown hairs disappear on their own. However, they can become infected; in this case, a doctor can make a small incision with a sterile scalpel to release the hair and drain the infection.