What is folliculitis?
Folliculitis is the name given to a group of skin conditions in which there are inflamed hair follicles. The result is a tender red spot, often with a surface pustule.
Folliculitis may be superficial or deep. It can affect anywhere there are hairs, including chest, back, buttocks, arms and legs. Acne and its variants are also types of folliculitis.
What causes folliculitis?
Folliculitis can be due to infection, occlusion, irritation and various skin diseases.
Types of folliculitis
Folliculitis due to infection
To determine if folliculitis is due to an infection, swabs should be taken from the pustules for culture in the laboratory.
Bacterial folliculitis is commonly due to Staphylococcus aureus. If the infection involves the deep part of the follicle, it results in a painful boil. Recommended treatment includes careful hygiene, antiseptic cleanser or cream, antibiotic ointment, and/or oral antibiotics.
Spa pool folliculitis is due to infection with Pseudomonas aeruginosa, which thrives in inadequately chlorinated warm water. Gram negative folliculitis is a pustular facial eruption also due to infection with Pseudomonas aeruginosa or other similar organisms. It usually follows tetracycline treatment of acne and is quite rare.
The most common yeast to cause a folliculitis is Pityrosporum ovale, also known as Malassezia. Malassezia folliculitis (Pityrosporum folliculitis) is an itchy acne-like condition usually affecting the upper trunk of a young adult. Treatment includes avoiding moisturisers, stopping antibiotics and topical antifungal or oral antifungal medication for several weeks.
Ringworm of the scalp (tinea capitis) usually results in scaling and hair loss, but sometimes results in folliculitis. In New Zealand, cat ringworm (Microsporum canis) is the commonest organism causing scalp fungal infection. Other organisms such as Trichophyton tonsurans are increasingly reported. Treatment is with oral antifungal agents for several months.
Folliculitis due to irritation from regrowing hairs
In the beard area irritant folliculitis is known as pseudofolliculitis barbae.
Irritant folliculitis is also common on the lower legs of women (shaving rash). It is frequently very itchy. You must stop removing the hairs. Do not recommence for about three months after the folliculitis has settled. A lady's electric razor is the gentlest way to remove hair from the limbs.
Folliculitis due to contact reactions
Paraffin-based ointments, moisturisers, and adhesive plasters may all result in a sterile folliculitis. If a moisturiser is needed, choose an oil-free product.
Coal tar, cutting oils and other chemicals may cause an irritant folliculitis. Avoid contact with the causative product.
Overuse of topical steroids may produce a folliculitis. Perioral dermatitis is a facial folliculitis provoked by moisturisers and topical steroids. Perioral dermatitis is treated with tetracycline antibiotics for six weeks or so.
Folliculitis due to immunosuppression
Folliculitis due to drugs
Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens, ACTH, lithium, isoniazid (INH), phenytoin and B-complex vitamins. Protein kinase inhibitors (epidermal growth factor receptor inhibitors) nearly always result in folliculitis.
Folliculitis due to inflammatory skin diseases
Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep seated sterile folliculitis. These include:
Treatment depends on the underlying condition and its severity. A skin biopsy is often necessary to establish the diagnosis.
Acne and acne-like disorders are also forms of folliculitis. These include:
The follicular occlusion syndrome refers to:
- hidradenitis suppurativa (acne inversa)
- acne conglobata (a severe form of nodulocystic acne)
- dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens); and;
- pilonidal sinus.
Folliculitis affecting the buttocks is quite common and is often nonspecific, i.e. no specific cause is found. Buttock folliculitis is equally common in males and females.
- Acute buttock folliculitis is usually bacterial in origin (like boils), resulting in red painful papules and pustules. It clears with antibiotics.
- Chronic buttock folliculitis does not often cause significant symptoms but it can be very persistent. Although antiseptics, topical acne treatments, peeling agents such as alpha hydroxy acids, long courses of oral antibiotics and isotretinoin can help buttock folliculitis, they are not always effective. Hair removal might be worth trying if the affected area is hairy. As regrowth of hair can make it worse, permanent hair reduction by laser or intense pulsed light (IPL) is best.
On DermNet NZ:
- Furunculosis (boils)
- Scalp folliculitis
- Oil folliculitis
- Gram negative folliculitis
- Spa pool folliculitis
- Pseudofolliculitis barbae (razor bumps)
- Pityrosporum folliculitis
- Folliculitis decalvans
- Patient information: Folliculitis (The Basics) – UpToDate (for subscribers)
Folliculitis – Medscape Reference