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Folliculitis

By

Wingfield E. Rehmus

, MD, MPH, University of British Columbia

Last full review/revision Feb 2021| Content last modified Feb 2021
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Folliculitis is an infection of hair follicles. Diagnosis is clinical. Treatment is with topical clindamycin.

The etiology of folliculitis is often unclear, but perspiration, trauma, friction, and occlusion of the skin are known to potentiate infection. The pathogen may be bacterial, fungal, viral, or parasitic. Bacterial folliculitis is usually caused by Staphylococcus aureus, but occasionally Pseudomonas aeruginosa (hot tub folliculitis) or other organisms have been reported. Hot tub folliculitis occurs because of inadequate chemical treatment of water. Acne Acne Vulgaris Acne vulgaris is the formation of comedones, papules, pustules, nodules, and/or cysts as a result of obstruction and inflammation of pilosebaceous units (hair follicles and their accompanying... read more Acne Vulgaris is a noninfectious form of folliculitis.

Symptoms and Signs

Symptoms of folliculitis are mild pain, pruritus, or irritation. Signs of folliculitis are a superficial pustule or inflammatory nodule surrounding a hair follicle. Infected hairs easily fall out or are removed by the patient, but new papules tend to develop. Growth of stiff hairs into the skin may cause chronic low-grade irritation or inflammation that may mimic infectious folliculitis (pseudofolliculitis barbae Pseudofolliculitis Barbae Pseudofolliculitis barbae is irritation of the skin due to hairs that penetrate the skin before leaving the hair follicle or that leave the follicle and curve back into the skin, causing a foreign-body... read more Pseudofolliculitis Barbae ).

Diagnosis of Folliculitis

  • Clinical evaluation

The primary skin finding in folliculitis is a pustule and perifollicular inflammation.

Microbiologic testing is not routinely indicated.

Treatment of Folliculitis

  • Clindamycin 1% lotion or gel

Because most folliculitis is caused by S. aureus, clindamycin 1% lotion or gel may be applied topically 2 times a day for 7 to 10 days. Alternatively, benzoyl peroxide 5% wash may be used when showering for 5 to 7 days. Extensive cutaneous involvement may warrant systemic therapy (eg, cephalexin 250 to 500 mg orally 3 to 4 times a day for 10 days). If these measures do not result in a cure, or folliculitis recurs, pustules are Gram stained and cultured to rule out gram-negative or methicillin-resistant S. aureus (MRSA) etiology, and nares are cultured to rule out nasal staphylococcal carriage. Potassium hydroxide wet mount should be done on a plucked hair to rule out fungal folliculitis.

Hot tub folliculitis usually resolves without treatment. However, adequate chlorination of the hot tub is necessary to prevent recurrences and to protect others from infection.

Key Points

  • Folliculitis can be caused by various pathogens and tends to be potentiated by perspiration, trauma, friction, and occlusion of the skin.

  • Bacterial folliculitis is usually caused by Staphylococcus aureus but occasionally Pseudomonas aeruginosa (hot tub folliculitis).

  • Treat staphylococcal folliculitis with clindamycin 1% lotion or gel or benzoyl peroxide 5% wash.

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Hidradenitis suppurativa is a chronic inflammatory condition of the hair follicle and associated structures. This condition can be present in the axillae, groin, and around the nipples and anus. In chronic axillary cases of hidradenitis suppurativa, which of the following is most likely to occur?
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