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InfectionCommonICD-10 L73.9

Bacterial folliculitis

Staphylococcal folliculitis · sycosis barbae (when on beard) · superficial folliculitis

Bacterial folliculitis is inflammation of the hair follicle most commonly caused by Staphylococcus aureus, manifesting as small pustules / papules with follicular distribution. It is distinguished from Pseudomonas (hot-tub) folliculitis, Pityrosporum folliculitis, EGFRi / BRAFi acneiform eruptions and acne vulgaris. UK clinical context includes nasal carriage of S. aureus, MRSA, occlusion, shaving, immunosuppression and biologic / chemotherapy-related neutropenia. NICE CKS folliculitis underpins UK primary-care management.

CurrentLast reviewed 16 May 2026
Clinical image of Bacterial folliculitis
Bacterial folliculitis. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Microbiology

  • Staphylococcus aureus — most common; including community and hospital MRSA.
  • Pseudomonas aeruginosa — hot-tub folliculitis (separate monograph).
  • Gram-negative: chronic antibiotic use (rare).
  • Pityrosporum (Malassezia) folliculitis — fungal; back / chest; pruritic; itraconazole-responsive.
  • Demodex folliculitis — rosacea overlap.
  • Herpetic sycosis — HSV.

Clinical features

  • Small 1-4 mm erythematous papules and pustules centred on hair follicles.
  • Sites: scalp, beard area, chest, back, buttocks, thighs.
  • Sycosis barbae: chronic beard folliculitis; deeper involvement; scarring.
  • Furunculosis: deeper follicular abscess (boil); risk of carbuncle / abscess.
  • Pseudofolliculitis barbae: ingrown hair, especially Fitzpatrick V-VI males.
  • Pruritus / mild discomfort; chronic disease may scar.
  • Risk factors: occlusion, shaving, hyperhidrosis, immunosuppression (HIV, transplant, chemotherapy, ICI), atopic eczema, diabetes, S. aureus nasal carriage, contact with infected individuals.

Differentials

  • Acne vulgaris — comedones present; pleomorphic; teenage / adult-onset.
  • Pityrosporum folliculitis — uniform pruritic monomorphic pustules on back / chest; itraconazole-responsive.
  • Pseudomonas (hot-tub) folliculitis — swimwear distribution; self-resolves.
  • EGFRi acneiform eruption — drug history.
  • Eosinophilic folliculitis — HIV / immunosuppression; intensely pruritic; eosinophilia.
  • Folliculitis decalvans, dissecting folliculitis — chronic scarring alopecia.
  • Pseudofolliculitis barbae — ingrown hair; mechanical.
  • Herpetic sycosis — HSV vesicles within beard hair-bearing area; PCR.

Investigations

  • Clinical diagnosis usually adequate.
  • Bacterial swab from pustule for culture & sensitivity in:
    • Refractory / recurrent disease.
    • Suspected MRSA.
    • Immunosuppressed patients.
  • Nasal / axillary / groin swabs for S. aureus carriage if recurrent.
  • KOH if Pityrosporum suspected (uniform pruritic back / chest).
  • HSV PCR if vesicular / unusual.
  • HIV testing if eosinophilic folliculitis / unusual chronic presentation.
  • FBC, CD4 if recurrent in immunosuppressed.

Management

  • Topical first-line:
    • Mupirocin 2% ointment / cream BD for 5-7 days.
    • Fusidic acid 2% (avoid prolonged courses — resistance).
    • Benzoyl peroxide 5% wash.
    • Chlorhexidine wash; antibacterial soap.
  • Oral:
    • Flucloxacillin 500 mg QDS for 7-10 days.
    • Penicillin-allergic: clindamycin 300 mg QDS or doxycycline 100 mg BD.
    • MRSA: doxycycline, co-trimoxazole, clindamycin, linezolid per culture / local protocol.
  • Pityrosporum folliculitis: itraconazole 200 mg OD for 7 days; ketoconazole shampoo / cream.
  • Decolonisation for recurrent disease:
    • Nasal mupirocin 2% BD for 5 days.
    • Chlorhexidine 4% body wash for 5-7 days.
    • Treat household members concurrently.
    • Wash bedding, towels, clothing in hot wash.
  • Adjunctive: shaving avoidance / change of method for sycosis / pseudofolliculitis; loose breathable clothing; weight management.
  • Counsel on hygiene; recurrence common in carriers.

References

  1. NICE CKS. Folliculitis, furuncles and carbuncles. London: NICE; accessed 18 May 2026.
  2. Stevens DL et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections. Clin Infect Dis. 2014;59:e10-e52.
  3. Liu C et al. Clinical practice guidelines by the IDSA for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis. 2011;52:e18-e55.
  4. British Association of Dermatologists. Folliculitis — patient information leaflet. London: BAD; 2023.

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