Folliculitis is an inflammation and/or infection of hair follicles. It appears as pink/red bumps or pustules at the site were hairs enter the skin. It can occur anywhere on the body, but typically affects hairy areas, such as the scalp, trunk, neck, underarms, extremities or groin. Causes include occlusion of the skin from wearing tight clothing and sweating, shaving of the beard or legs, exposure to irritants, diabetes, long term use of antibiotics and immunocompromised states.

Pseudofolliculitis barbae - Occurs primarily in African-American men and is caused by shaving. The shaved hair is sharp and curly and penetrates the skin and causes irritation.

Hot tub folliculitis – This occurs after exposure to hot tubs, and causes widespread pustules on the trunk, legs and arm that were immersed in the water. It may be worse underneath the bathing suit. Pseudomonas bacteria is the culprit, and the disease is normally self-limited. In severe cases, the oral antibiotic ciprofloxacin is used.

Staphylococcus folliculitis - This common type is marked by itchy, white, pus-filled bumps that can occur anywhere on your body where hair follicles are present. When it affects a man's beard area, it is called barber's itch. It occurs when hair follicles become infected with Staphylococcus aureus (staph) bacteria. This can occur through shaving, scratching or with an injury to the skin.

Pityrosporum folliculitis. Especially common in teens and adult men, pityrosporum folliculitis is caused by a yeast (pityrosporum) and produces chronic, red, itchy pustules on the trunk,  neck, upper arms and face. It can be misdiagnosed as acne.