folliculitis
Meaning of folliculitis: The giveaway is the pattern: every bump sits on a hair, which separates it from skin infections that spread without regard to follicles.
Definition of folliculitis
Folliculitis is inflammation of one or more hair follicles, the small pockets in the skin that each grow a hair. It appears as small red bumps or pus filled spots centered on hairs, most often on the scalp, face, neck, chest, back, buttocks and thighs. Most cases stay in the upper part of the follicle and settle without leaving a mark.
What sets it off?
| Cause | What points to it |
|---|---|
| Bacteria already living on the skin | The commonest form; pus filled spots on hair bearing skin |
| Shaving, waxing or plucking | Bumps in the beard area or on the legs, often with ingrown hairs |
| Friction, sweat and occlusion | Spots under tight clothing, straps, dressings or heavy ointments |
| Poorly treated warm water | Itchy bumps appearing on the trunk a day or two after a soak |
| Yeast normally present on skin | Uniform itchy bumps on the upper back and chest in humid conditions |
Not every case involves an infection. Certain medications, including corticosteroids and some targeted cancer drugs, produce a rash that looks like folliculitis but arises from the drug's effect on the follicle rather than from bacteria growing in it.
How deep can it go?
Superficial folliculitis involves only the opening of the follicle and heals without scarring. When infection tracks further down, one follicle can become a boil, a tender lump with pus collected inside. Several neighboring follicles involved together form a carbuncle, a larger and deeper mass draining from more than one point. Deeper still, pus can collect in the surrounding tissue as an abscess. Repeated deep episodes can destroy the follicle permanently, leaving a bald patch or a scar where hair no longer grows.
What else looks like it?
Acne shares the follicle as its starting point but adds blackheads and whiteheads, which folliculitis does not produce. Cellulitis spreads as a sheet of warm redness through the deeper skin and ignores follicle boundaries entirely. Razor bumps in the beard area come from curved hairs curling back into the skin and are inflammatory rather than infectious. Keratosis pilaris produces rough, persistent bumps on the upper arms and thighs with no pus and no tenderness.
Used in a sentence
Examination revealed folliculitis affecting the scalp, with several small pustules centered on hair follicles.
Good to know
Folliculitis is centered on hair follicles, which distinguishes it from cellulitis, an infection that spreads through the deeper skin without following follicle boundaries.
Word origin
Where “folliculitis” comes from
Formed from Latin folliculus, meaning a small sac, and the Greek suffix -itis, meaning inflammation.