Definition
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Folliculitis: inflammation of the hair follicles, usually due to infection, irritation, or obstruction.
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Typically presents as small, erythematous papules or pustules centered on hair follicles.
Epidemiology & Risk Factors
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Common in all age groups; more frequent in adults.
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Risk factors:
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Bacterial infection (most commonly Staphylococcus aureus)
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Occlusive clothing, friction, sweating
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Hot tubs or swimming pools (Pseudomonas aeruginosa)
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Immunosuppression or diabetes
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Clinical Features
| Feature | Description | High-Yield Points |
|---|---|---|
| Lesions | Small, erythematous papules or pustules | Centered on hair follicle; may have hair in center |
| Distribution | Can occur anywhere with hair; commonly beard, scalp, chest, back, thighs | Hot tub folliculitis: trunk and buttocks |
| Symptoms | Pruritus, mild tenderness | Pain uncommon unless deep infection |
| Chronicity | Often recurrent if underlying cause persists | Shaving or friction can perpetuate lesions |
Special Types:
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Hot tub folliculitis → Pseudomonas, occurs 8–48 hrs after swimming.
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Gram-negative folliculitis → often in patients on long-term antibiotics for acne.
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Fungal folliculitis → Malassezia in seborrheic areas.
Differential Diagnosis
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Acne vulgaris – comedones, papules, pustules, more widespread
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Furuncle (boil) – deeper infection, larger tender nodule
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Carbuncle – coalesced boils, systemic symptoms
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Eczema – scaling, pruritus, no pustules centered on follicles
Investigations
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Usually clinical diagnosis.
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Bacterial culture if:
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Recurrent or severe
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Unresponsive to first-line therapy
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Fungal or viral swab if atypical features
Management
General Measures
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Stop shaving or friction over affected area.
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Use antibacterial washes (chlorhexidine, benzoyl peroxide).
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Warm compresses to aid drainage.
Topical Therapy
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Mild bacterial folliculitis: topical antibiotics (mupirocin or fusidic acid)
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Fungal folliculitis: topical antifungals (ketoconazole)
Systemic Therapy
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Extensive or recurrent bacterial folliculitis: oral antibiotics (flucloxacillin or cephalexin)
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Pseudomonas (hot tub folliculitis): usually self-limiting; ciprofloxacin for severe cases
Complications
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Furunculosis or carbuncle formation
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Cellulitis if infection spreads to dermis
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Scarring or hyperpigmentation with repeated episodes
PLAB-Style Questions
Q1: A 28-year-old man presents with multiple 2–3 mm pustules over the beard area after shaving. Lesions are centered around hair follicles and mildly pruritic. Most likely diagnosis?
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A. Acne vulgaris
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B. Folliculitis
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C. Impetigo
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D. Rosacea
✅ Answer: B. Folliculitis
Q2: A patient develops erythematous pustules on the trunk 24 hours after using a hot tub. Which organism is most likely responsible?
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A. Staphylococcus aureus
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B. Pseudomonas aeruginosa
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C. Streptococcus pyogenes
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D. Malassezia species
✅ Answer: B. Pseudomonas aeruginosa
High-Yield Pearls
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Folliculitis = small pustules or papules centered on hair follicles.
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Most commonly bacterial (S. aureus), but can be fungal or viral.
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Hot tub folliculitis → Pseudomonas, usually self-limiting.
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Topical antibiotics for mild cases; systemic antibiotics for extensive/recurrent lesions.
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Distinguish from acne by absence of comedones.
