No discussion of skin is complete without considering the contribution of the hair to the physiology of the skin. Different hair architecture accompanies different skin colors; thus, the hair and the skin are inter-related special considerations. Caucasian persons with very fair skin typically have straight to slightly curly hair while African American persons with dark skin typically have kinky hair; however, many variations exist. Follicular skin problems are usually minimal in Caucasian, Asian, Hispanic, and Mediterranean individuals where the oval to elliptical hair cross-section yields body hair that is straight to curly. Unique follicular problems exist in African American persons where the flattened elliptical hair cross-section yields tightly kinked hair. This tight kink predisposes the hair to ingrowing, especially on the face, in the armpits and groin, and on the legs. Shaving of the hair in any of these areas cuts the hair at an angle and the tight kink of the hair shaft allows the short hair to re-enter the skin after exiting the follicular ostia due to the sharp tip. The ingrown hair then burrows beneath the skin surface causing inflammation, which can result in the formation of a pustule, the appearance of post-inflammatory hyperpigmentation, and/or a scar. When these findings arise in connection with ingrown facial hairs, it is known as pseudofolliculitis barbae.
This means that African American persons can develop skin disease based on the manner in which they groom their body hair. This problem with ingrown hairs explains why many African American women do not shave their armpits, groin, and legs. It also explains why many African American men wear a short beard. The only way to avoid the ingrown hair is to keep the hair so short that it cannot ingrow, which may mean twice daily
shaving for some, or to allow the hair to grow so long that it cannot ingrow, which is much simpler. Depilatories, waxing, and laser hair removal techniques are generally not an option in African American individuals, since these methods do not work well on the deeply pigmented kinky hair shafts.