Folliculitis

Aetiology and Pathophysiology

Non-infective Folliculitis

• Often related to:

  • Mechanical irritation or maceration (e.g. tight clothing, heavy sweating).

  • Contact with occlusive substances (oils, cosmetics).

  • Shaving or waxing (ingrown hairs).

  • Drugs (e.g. corticosteroids, epidermal growth factor receptor [EGFR] inhibitors, checkpoint inhibitors, certain antiepileptics).

  • Obesity may contribute via skin folds and sweating.

Infective Folliculitis

Common organisms or agents include:

1. Bacterial

   • Staphylococcus aureus: the most frequent cause of bacterial folliculitis.

   • Pseudomonas aeruginosa: associated with “hot tub” or “spa” folliculitis.

2. Fungal

   • Malassezia yeasts (causing Pityrosporum folliculitis).

   • Dermatophytes (e.g. Tinea species).

3. Viral

   • Herpes simplex virus (HSV) – can present as folliculitis-like lesions.

4. Parasitic

   • Demodex mites (rare, but implicated in certain persistent cases).

Clinical Presentation

• Patients often describe tender or itchy papules/pustules centred on hair follicles.

• Lesions can have a halo of erythema; some may have an overlying crust if they rupture.

• Distribution is frequently in areas of high friction and moisture (beard area, scalp, groin, back, buttocks).

Red Flags or Alarm Features (though relatively uncommon in straightforward folliculitis) include:

• Extensive or rapidly worsening lesions suggesting severe infection (e.g. boils, abscess formation).

• Systemic symptoms such as fever, malaise, or lymphadenopathy that may indicate spreading infection.

Differential Diagnosis

• Acne vulgaris: tends to involve comedones (blackheads/whiteheads) rather than purely follicular pustules.

• Periorificial dermatitis: usually perioral or periocular papules, with sparing of the vermilion border.

• Pseudofolliculitis barbae: caused by ingrown hairs, commonly in the beard area.

• Cutaneous fungal infections (tinea): may present similarly, though with typical ring-like lesions in many cases.

• Eosinophilic folliculitis: more common in immunocompromised patients (e.g. HIV).

Investigations

1. Clinical Diagnosis

   • Most cases are diagnosed clinically based on morphology and distribution.

2. Swabs / Scrapings

   • If infective folliculitis is suspected, a bacterial swab for culture and sensitivity (especially if lesions are severe, recurrent, or not responding to empirical treatment).

   • Consider fungal scrapings or fungal culture if dermatophytes or Malassezia are suspected (Pityrosporum folliculitis).

   • PCR for herpes simplex if herpetic infection is a possibility.

3. Additional Tests

   • In recalcitrant or atypical cases, or if there is suspicion of underlying immunosuppression, consider basic investigations (FBC, blood glucose, HIV testing).

Management

General Measures

• Identify and remove triggers:

  • Avoid occlusive clothing and products (oils, heavy moisturisers) on affected areas.

  • Use clean, sharp razors (change frequently); consider alternative hair-removal methods if shaving-induced.

  • Limit friction and sweating (looser clothing, address obesity if relevant).

• Local supportive care:

  • Warm compresses to soften lesions and encourage drainage.

  • Antiseptic washes (e.g. chlorhexidine) can help reduce bacterial load.

  • Advise adequate skin hygiene but avoid over-washing, which can irritate the skin further.

Management of Non-infective Folliculitis

• Primarily involves the general measures listed above.

• Consider adjusting or ceasing offending medications (in consultation with the relevant specialist) if they are implicated.

• Topical anti-inflammatory agents (e.g. mild topical corticosteroids) may be considered in some cases if inflammation is significant, but typically short term.

Management of Infective Folliculitis

1. Staphylococcal Folliculitis

   • If confirmed or strongly suspected S. aureus, treat as per impetigo guidelines (Therapeutic Guidelines).

   • Mild localised infections:

     • Topical mupirocin 2% ointment or fusidic acid cream.

   • More extensive or recurrent infections:

     • Oral antibiotics (e.g. flucloxacillin).

     • For penicillin-allergic patients, consider cefalexin or another suitable antibiotic based on culture results.

   • Nasal carriage of S. aureus:

     • Consider intranasal mupirocin if recurrent folliculitis is linked to nasal staphylococcal carriage.

2. Pseudomonas (“Hot Tub”) Folliculitis

   • Identify the source (e.g. spa, swimming pool, wetsuits) and ensure adequate disinfection.

   • Usually self-limiting once exposure to the contaminated water source is avoided.

   • Severe or persistent cases may require oral antibiotics (e.g. ciprofloxacin) as per susceptibility patterns.

3. Malassezia Folliculitis (Pityrosporum Folliculitis)

   • Presents with monomorphic follicular papules, often on the trunk, sometimes itchy.

   • Manage similarly to pityriasis versicolor:

     • Topical azole or selenium sulphide shampoos/lotions (applied to affected areas).

     • Resistant or severe cases can require oral antifungals (e.g. itraconazole).

4. Dermatophyte Folliculitis

   • Usually needs oral antifungal treatment (e.g. terbinafine or itraconazole), as topical antifungals may not penetrate deeply enough.

5. Viral / Parasitic Causes

   • HSV-related lesions may benefit from antiviral therapy (e.g. aciclovir).

   • Demodex infestation might respond to topical ivermectin (off-label) or permethrin cream.

When to Refer

• Recalcitrant or atypical folliculitis not responding to standard measures, or recurring frequently.

• Suspicion of an underlying immunocompromised state or unusual pathogen.

• Extensive scarring or significant post-inflammatory changes requiring dermatological interventions (e.g. laser therapy).