AKT · Dermatology/Infections & infestations

Folliculitis

Inflammation/infection of the hair follicle (commonly S. aureus)

Overview

Inflammation of the hair follicle, most often a superficial bacterial infection (Staphylococcus aureus). Each pustule is centred on a hair — the discriminator from acne (no comedones) and from a boil (deeper). "Hot-tub" folliculitis is a Pseudomonas variant after whirlpool/spa exposure.

Recognise

Small follicular papules and pustules, each pierced by a hair, with surrounding erythema
Sites of friction/occlusion/shaving — beard, thighs, buttocks, scalp
Hot-tub (Pseudomonas) folliculitis: itchy pustules on the trunk 1–2 days after a spa/whirlpool

Red flags

Deeper/spreading infection → furuncle (boil), carbuncle or cellulitis; recurrent → Staph carriage or immunosuppression/diabetes

Differentials & how to tell them apart

Acne vulgariscomedones present, polymorphic, not every lesion follicular-pustular

Furuncle/boila deeper, tender, fluctuant nodule of a single follicle

Pseudofolliculitis barbaeingrowing hairs after shaving, not primarily infective

Keratosis pilarisrough non-inflamed follicular papules, upper arms/cheeks

Clinical image

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Folliculitis — clinical imagesDermNet

Investigations

Clinical. Swab if recurrent, severe, or not responding (Staph aureus, MRSA, Pseudomonas).

Management

Antiseptic measures ± topical antibiotic; oral flucloxacillin if extensive/deep

1Mild superficial folliculitis → antiseptic wash, avoid the trigger (occlusion, shaving over it). Localised bacterial → topical antibiotic.Gate: Hot-tub folliculitis is PSEUDOMONAS and usually self-limiting (no antibiotic needed) — the spa exposure history changes the organism and the management
2Extensive/deep (furuncle, carbuncle) or systemic features → oral flucloxacillin; recurrent Staph → swab nose/skin and decolonise; check for diabetes/immunosuppression.

Antiseptic wash / good skin hygiene — mild superficial folliculitis often settles with this alone

Topical antibiotic — localised bacterial folliculitis

Oral flucloxacillin — extensive or deeper (furunculosis); decolonisation if recurrent Staph carriage

Key points

A boil (furuncle) is a deeper folliculitis; a carbuncle is several coalescing. Recurrent folliculitis warrants a diabetes and carriage check.

Monitor & prognosis

Resolution; recurrence prompts carriage/glucose check.

Superficial folliculitis resolves; deeper lesions may scar.

Source: NICE CKS Boils, carbuncles, and staphylococcal carriage; DermNet