What is folliculitis?
Folliculitis is an inflammation of the upper part of the hair follicle. It usually arises from an infection with a bacterium, a fungus, a virus or a yeast. The infection usually leads to a small pus head at the hair follicle, often with itchy or painful skin.
What is it not?
Although folliculitis can resemble acne, it is fundamentally different: acne is mainly an inflammation of the sebaceous glands and not only of the upper part of the follicle. Other conditions that look like folliculitis but are not include acne rosacea, perioral dermatitis and pseudofolliculitis.
What does it look like?
Typical are the small pus heads in the opening of the hair follicle. Pus heads can break, causing superficial wounds that may produce yellow fluid. The inflammation can also spread deeper into the skin, giving red, painful bumps. All these forms can occur together.
Where does folliculitis develop?
Almost the entire skin (except the palms and soles) is covered with hair follicles, so folliculitis can arise almost anywhere. Which micro-organism causes it depends partly on the area infected — for example, Staphylococcus aureus and Pityrosporum yeast on the face; staphylococci (from shaving), yeasts and fungi in the beard area; staphylococci and dermatophytes on the scalp; and Malassezia yeast or Pseudomonas on the trunk.
Types by cause and treatment
Staphylococcus aureus folliculitis. By far the most common form. Foci can occur spread over the whole skin, very locally or extensively. The bacterium can strike especially where the skin is shaved (beard area, armpits, pubic area). It usually causes small, fairly superficial pustules, but sometimes the deeper part of the follicle is affected and abscesses (carbuncles) can form; deeper follicle inflammations in the beard region are called “sycosis”. People who regularly have staphylococcal folliculitis may be carriers of the bacterium, with a source in the nose, ears or around the anus from which the bacterium keeps spreading; skin cultures can trace these sources. Folliculitis can be cured with antibiotics, but in many cases antiseptic products (povidone-iodine soap or chlorhexidine cream) are enough. Good hygiene is important for recurring infections.
Pseudomonas aeruginosa folliculitis (“hot-tub folliculitis”). Unlike many bacteria, Pseudomonas is fairly resistant to chlorinated pool water. People using a contaminated hot tub or jacuzzi can develop, within a few days, a strongly itchy folliculitis over the whole skin, but especially the areas covered by swimwear. Healing usually occurs on its own within about 10 days.
Malassezia folliculitis (“yeast spots”). This yeast infection is common, characterised by countless small pustules on the back and chest, more rarely the arms and face. The source of the yeast is usually on the scalp, where the same Malassezia yeast can also cause the eczema commonly known as dandruff. It is treated with anti-yeast creams, usually combined with an anti-yeast shampoo to combat the reservoir on the scalp.
Folliculitis from fungi. Fungi (mainly dermatophytes) can also cause folliculitis, though relatively rarely. The infection always sits deep in the follicle, so an antifungal cream (as used for athlete’s foot) is insufficient, and the doctor will usually prescribe antifungal tablets. Many of the fungi causing this are transmitted by (pet) animals.
How is the diagnosis made?
Often the doctor can already tell by sight which kind of folliculitis it is, or most likely is. If there is doubt, a culture of the pustule contents can be taken; since the result often takes days to weeks, extensive folliculitis is usually treated with a medicine against the most likely cause in the meantime.
When to see a doctor
See a doctor if pustular, itchy or painful spots around hair follicles are widespread, deep, painful or keep returning, or do not respond to good hygiene and antiseptic care.