Folliculitis
Folliculitis is inflammation or infection of hair follicles, split into bacterial, fungal, and irritant causes, per the Cochrane review of bacterial folliculitis and boils.
Symptoms
Small red bumps or white-topped pustules centered on hair follicles, often itchy or mildly tender, most common on the scalp, beard area, chest, back, and thighs.
Causes and risk
Staphylococcus aureus is the most common bacterial cause; Malassezia yeast causes an itchy, antibiotic-resistant form, and Pseudomonas causes "hot tub folliculitis" from contaminated water, per systematic review data. Shaving, tight clothing, and occlusive skin products are common triggers.
How it is evaluated
Diagnosis is usually clinical based on appearance and distribution; a culture or KOH prep helps distinguish bacterial from fungal folliculitis when the diagnosis is unclear or treatment fails, since antibiotics do not treat the fungal form.
Treatment
Warm compresses and antibacterial or antifungal washes handle mild cases; oral antibiotics are reserved for more extensive or persistent bacterial folliculitis, and incision and drainage is used for boils (furuncles) or clusters of boils (carbuncles).
When to seek care
Fever, spreading redness beyond the follicles, swollen lymph nodes, or a growing abscess should prompt prompt medical evaluation, especially in someone immunocompromised.