Folliculitis and pseudofolliculitis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

The follicle-centred papule or pustule is a pattern, not a microbiological diagnosis. Ask about pain versus itch, shaving and plucking, body site, hot tubs, sweating, occlusive clothing, antibiotics, corticosteroids, immunosuppression, sexual exposure and household recurrence. Examine whether each lesion is centred on a hair and look closely for a curved hair entering adjacent skin, crust, grouped vesicles, fluctuance, spreading inflammation and scarring.

Pseudofolliculitis commonly affects beard, neck, pubic, axillary and leg hair after close removal. It can affect anyone but is more frequent when hair is tightly curled and re-enters the epidermis. In darker skin, surrounding erythema may be subtle while tender elevation, brown macules and keloidal papules are conspicuous. Discuss occupational or cultural requirements sensitively before advising a change in shaving practice.

Bacterial folliculitis is usually superficial and localised but recurrent disease may reflect nasal carriage, shared razors, contaminated equipment, diabetes or immune compromise. Treatment ranges from hygiene and removal of the exposure to a short targeted topical antimicrobial; abscess, cellulitis and systemic illness follow different pathways. Avoid repeated empirical antibiotic courses that suppress one episode while missing ingrown hairs, Malassezia or hidradenitis.

Key points

Folliculitis describes follicle-centred inflammation; determine whether the driver is bacterial infection, yeast, water exposure, occlusion, medicine, friction or an ingrowing hair before prescribing.
Pseudofolliculitis is a sterile foreign-body reaction to a cut hair re-entering skin and is common with tightly curled or coarse hair, especially after close shaving, waxing or plucking.
Visible or palpable ingrown hairs, papules aligned with the shaved area and post-inflammatory pigment change support pseudofolliculitis rather than bacterial infection.
Small monomorphic pustules centred on hairs can be staphylococcal folliculitis; obtain a fresh pustule swab when disease is recurrent, extensive, treatment-resistant or accompanied by household transmission.
Abrupt follicular pustules after a poorly maintained hot tub suggest Pseudomonas and often settle without antibiotics in an otherwise well person.
Itchy monomorphic upper-trunk papules or pustules, often after heat, occlusion or antibiotics, suggest Malassezia folliculitis and will not improve with antibacterial escalation.
Stopping close hair removal for four to six weeks is the most effective pseudofolliculitis intervention; if hair removal continues, use guarded clippers, leave short stubble and avoid stretching or repeated passes.
Persistent pigment or keloid scarring deserves active prevention and dermatology input; it is not evidence that a bacterial infection remains.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Bacterial follicular infection

Staphylococcus aureus commonly enters a damaged follicular opening after shaving, friction or occlusion; Gram-negative organisms and Pseudomonas follow particular antibiotic or water exposures.

Ingrowing cut hair

A closely cut, plucked or waxed hair retracts and curves through adjacent epidermis, especially when the shaft is tightly curled or coarse.

Yeast-associated overgrowth

Malassezia proliferates in warm, oily and occluded skin and can dominate after antibacterial exposure alters competing flora.

Host and medicine factors

Diabetes, immune compromise, systemic or topical corticosteroids and epidermal growth factor receptor inhibitors can predispose to infectious or sterile follicular eruptions.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Superficial follicular inflammation
Microbial invasion confined to the follicular infundibulum produces a small pustule centred by a hair with limited perifollicular inflammation.
2
Foreign-body reaction
An ingrown hair shaft penetrates epidermis or dermis, provoking sterile granulomatous inflammation and a tender papule rather than primary infection.
3
Progression to abscess
Deeper bacterial extension can form a furuncle or coalescent abscess, requiring drainage assessment rather than simply increasing topical treatment.
4
Inflammation-driven dyspigmentation
Repeated papules and manipulation stimulate persistent pigment change and sometimes keloidal repair, particularly in susceptible richly pigmented skin.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Follicle-centred pustule

A small pustule pierced by a hair with surrounding tenderness or crust supports superficial bacterial folliculitis, especially when lesions vary in stage.

Ingrown-hair papule

A looped or buried hair is visible or palpable beneath a papule in a recently shaved area, often with prominent residual hyperpigmentation.

Malassezia pattern

Intensely itchy, highly monomorphic follicular papules and pustules on upper trunk, shoulders or hairline after sweating, occlusion or antibiotics favour yeast-associated disease.

Hot-tub pattern

Sudden follicular pustules under swimwear one to four days after spa-pool exposure suggest Pseudomonas folliculitis, particularly when several users are affected.

Invasive infectionRed flag

Spreading warmth or colour change, rapidly increasing pain, fever, hypotension, fluctuance or necrosis signals cellulitis, abscess or deeper infection requiring urgent management.

Red flags requiring action

Fever, hypotension, rapidly spreading cellulitis, disproportionate pain, perineal necrosis, orbital or central-facial extension, immunosuppression with progression, grouped vesicles near the eye or a fluctuant abscess requires urgent assessment.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Hair-removal and exposure historyFirst step
Why
Separate ingrowing-hair inflammation from infectious, water-associated, occlusive and medicine-related causes.
Interpretation and limitations
A reproducible eruption after close shaving with visible ingrown hairs can establish pseudofolliculitis without microbiological testing.
02
Swab of a fresh intact pustule
Why
Identify bacteria and susceptibility in recurrent, extensive or treatment-resistant suspected infection.
Interpretation and limitations
Clean surface contamination, open a fresh pustule aseptically and provide site, recurrence, antibiotics and exposure details; colonisation must match the clinical pattern.
03
Fungal microscopy or sampling
Why
Assess monomorphic itchy truncal disease or a dermatophyte folliculitis pattern before antifungal treatment.
Interpretation and limitations
Sampling method depends on the suspected organism; prior topical or oral antimicrobials reduce yield and should be documented.
04
Viral swab from a fresh vesicle
Why
Confirm herpes simplex or zoster when lesions are grouped, painful or erosive.
Interpretation and limitations
Unroof a suitable new vesicle according to local protocol and request PCR; do not delay urgent antiviral or ophthalmic action when the clinical risk is high.
05
Metabolic and immune assessment when recurrent
Why
Look for diabetes, neutropenia, immunosuppression or another predisposing disorder when history supports it.
Interpretation and limitations
Select HbA1c, FBC, HIV testing with consent or other tests according to risk; ordinary isolated folliculitis does not require a blanket panel.
06
Biopsy of scarring or atypical follicular disease
Why
Investigate keloidal folliculitis, inflammatory alopecia, eosinophilic disease or another persistent mimic.
Interpretation and limitations
Choose an active edge, obtain consent and tell histopathology about site, hair-removal practice, infection results and suspected scarring process.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Acne vulgaris

Comedones and a polymorphic mixture of papules, pustules and nodules over acne-prone sites distinguish acne from monomorphic folliculitis.

Hidradenitis suppurativa

Deep recurrent flexural nodules with double comedones, tunnels and rope-like scars represent chronic follicular occlusion rather than superficial folliculitis.

Herpes infection

Grouped painful vesicles, recurrent erosion at one site or dermatomal spread requires viral testing and risk-based antiviral or ophthalmic care.

Inflammatory follicular dermatosis

Scarring alopecia, keloidal plaques, eosinophilic disease and medicine eruptions require dermatological assessment when infection and ingrown hairs do not explain the course.

Additional chapter-specific clues

Herpetic mimic

Painful grouped vesicles, punched-out erosions or recurrent lesions at one site are not ordinary bacterial folliculitis and prompt viral sampling and exposure assessment.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01PseudofolliculitisRelease the close-shaving triggerFirst stepPapules with ingrown hairs follow shaving, plucking or waxing without spreading infection.

1Explain the sterile foreign-body mechanism and, where feasible, stop close hair removal for four to six weeks while treating any confirmed superinfection separately.
2If removal must continue, use guarded electric clippers leaving short stubble, soften hair, shave with the grain without stretching skin, make one light pass and clean equipment.
3Consider a non-antibiotic keratolytic or retinoid approach off label for persistent papules, and refer scarring or occupationally intractable disease for laser-hair-reduction discussion with skin-tone expertise.

02Limited bacterial folliculitisTreat a defined infectious episodeLocalised superficial pustules fit bacterial folliculitis and there is no abscess, cellulitis or systemic illness.

1Remove contaminated shaving or occlusive exposure, use gentle washing, do not share razors or towels and collect a fresh sample when recurrence or prior failure makes it useful.
2For a small susceptible bacterial field, use a short topical mupirocin course according to local antimicrobial guidance rather than repeated widespread empirical application.
3Review response and culture; investigate carriage, equipment, household clusters or host risk when recurrence continues and avoid automatic long-term decolonisation.

03Atypical or severe patternMatch escalation to the causeEscalationDisease is widespread, recurrent, monomorphic and itchy, vesicular, fluctuant, spreading or associated with systemic illness.

1Assess physiology and depth, drain an abscess when indicated, and follow cellulitis or sepsis guidance for invasive bacterial infection.
2Use exposure-led fungal or viral sampling for Malassezia or herpes and choose organism-specific treatment rather than adding another antibacterial.
3Refer persistent scarring, hair loss, keloidal plaques or an unclear immunocompromised presentation for dermatology assessment and possible biopsy.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

A short targeted option for a limited susceptible bacterial skin infection, including selected localised folliculitis, guided by local antimicrobial policy.

Mupirocin 2% ointment

Apply a small amount to the affected area two to three times daily for up to ten days, using a dressing only if clinically appropriate.

Avoid prolonged or repeated use, eyes and mucosa; stop for sensitisation, consider resistance and polyethylene-glycol absorption over large damaged areas or in renal impairment.

A non-antibiotic option that can reduce follicular plugging and inflammation when hair-removal modification alone is insufficient.

Adapalene 0.1% with benzoyl peroxide 2.5% gel

Apply a thin film once daily in the evening to affected hair-bearing skin as an off-label pseudofolliculitis strategy, introducing alternate-day or short-contact use if sensitive.

Explain off-label use; contraindicated in pregnancy and pregnancy planning, avoid mucosa and freshly shaved or broken skin, manage irritation and warn about fabric bleaching.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Abscess and cellulitis

Bacterial disease can extend beyond the follicle into a fluctuant collection or spreading dermal and subcutaneous infection with systemic illness.

Recurrent resistant infection

Repeated empirical antimicrobials select resistance and leave household, equipment or carriage reservoirs unaddressed, producing progressively harder-to-treat episodes.

Scarring and keloid formation

Deep inflammation, picking and chronic ingrown hairs can cause hypertrophic or keloidal plaques and permanent alteration of hair-bearing skin.

Post-inflammatory colour change

Flat hyperpigmented or hypopigmented macules can persist long after active follicular inflammation and may drive damaging attempts at further treatment.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Review whether papules stopped appearing after the hair-removal change; residual flat hyperpigmentation can outlast active pseudofolliculitis by months.
For suspected infection, track fever, spreading inflammation, pain, abscess formation and culture result rather than relying on pustule colour alone.
After a targeted topical antibiotic, document clinical response and stop at the planned endpoint; repeated failure prompts organism and diagnosis review.
Check for new keloids, atrophic scars or hair loss and refer early when ongoing inflammation threatens permanent structural change.
Photographs of beard, pubic or other intimate sites need specific informed consent, minimal necessary framing, secure storage and a clear clinical purpose.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

A bent hair is diagnostic evidence

Magnification may reveal a shaved hair curving back into skin, directly linking morphology to the mechanical cause.

Leave some stubble

Guarded clipping prevents the sharpened hair tip retracting below the follicular opening and re-entering adjacent epidermis.

Itch changes the organism hypothesis

Uniform intensely itchy truncal pustules after antibiotics are more compatible with Malassezia than resistant staphylococci.

Pigment is not pus

Brown macules remaining after papules flatten reflect post-inflammatory change and do not warrant another antibacterial course.

Occupation belongs in the plan

When a workplace requires close shaving, documentation and alternative grooming standards may prevent repeated disease more effectively than medicine alone.

11Common pitfallsFrequent interpretation and management errors.

01
Calling pseudofolliculitis recurrent infection and prescribing repeated antibiotics without ever inspecting for an ingrown hair.
02
Advising closer shaving to remove bumps, which drives sharpened hair tips beneath the skin and worsens inflammation.
03
Swabbing old open drainage after antibiotics and treating every colonising organism as the primary cause.
04
Escalating antibacterial therapy for monomorphic itchy truncal folliculitis without considering Malassezia.
05
Missing hidradenitis when deep recurrent groin or axillary lesions have tunnels and scars rather than superficial follicular pustules.
06
Ignoring occupational, religious or personal hair-removal priorities when designing a technically correct but unusable plan.