In-grown hair is a condition where the hair curls back or grows sideways into the skin. It may or may not be accompanied by an infection of the hair follicle or "razor bumps", which vary in size. In-grown hair most commonly appears in areas where the skin is shaved or waxed.

All types of acne — blackheads, whiteheads, pimples, and cysts — develop when pores in our skin become clogged. The culprit is sebum [see-bum], a type of oil in our skin. Our bodies make more sebum when our hormones surge.

Razor bumps, also called pseudofolliculitis barbae, are small, irritated bumps on the skin that develop after shaving when strands of hair curl back on themselves and grow into the skin. Razor bumps cause irritation and the development of pimples. They also may cause scarring.

Razor burn is a skin condition caused by shaving too closely, incorrectly, or sometimes merely by shaving in sensitive areas, especially when people have easily irritated skin. It can look like a small red rash, feature bumps, or even cause infected pimples or blisters. Razor burn can itch severely, making the skin very uncomfortable for several days. More mild cases can result in a couple of hours of discomfort and reddish skin.