Dermatology & Infectious Diseases & Family Medicine
Folliculitis
Folliculitis is an inflammation - most often infectious - of the hair follicle, confined to its superficial portion (follicular infundibulum). It manifests itself clinically as small erythematous pustules or papulopustules centered on a hair, scattered over the hairy areas of the body. Unlike furuncle - which involves deep infection of the entire follicle and perifollicular tissue, with formation of a subcutaneous abscess - folliculitis is a superficial lesion, not very painful, rarely complicated and often resolving spontaneously within a few days. Aetiologically, folliculitis is most often bacterial, caused by Staphylococcus aureus in the majority of cases, but other agents may be involved depending on the clinical context: Pseudomonas aeruginosa (spa folliculitis or hot-tub folliculitis), Klebsiella or Enterobacter (Gram-negative folliculitis in patients treated long-term with antibiotics for acne), Malassezia furfur (fungal folliculitis - pityrosporum folliculitis), or Demodex folliculorum (parasitic folliculitis). Non-infectious folliculitis also exists - eosinophilic folliculitis (associated with HIV + hematological neoplasia), decalcifying folliculitis (fibrosing scalp variant), pseudofolliculitis of the beard (ingrown hair in men with curly hair), contact folliculitis (oils + occlusive creams + make-up) - and requires a different therapeutic approach. Folliculitis affects all age groups, with a higher incidence in adolescents and young adults, athletes (shaving + equipment rubbing), obese people, diabetics and the immunocompromised.
Types, risk factors, and diagnosis
- Etiological classification and clinical presentation superficial bacterial folliculitis caused by S. aureus (most frequent): papulo-pustules centered on a hair + perifollicular erythema + slight tenderness + no deep induration - preferential localizations : face (beard area) + scalp + nape of neck + limbs + buttocks + thighs + armpits - pruritus often present - no fever or lymphadenopathies - spontaneous evolution towards resolution in 7-10 days or towards extension (aggravation, formation of a boil if deep extension); spa folliculitis (hot-tub folliculitis - Pseudomonas aeruginosa): context: exposure to an insufficiently chlorinated whirlpool bath, swimming pool or jacuzzi in the preceding 8-48h - lesions: pruritic + erythematous papulo-pustules on areas covered by bathing suit + trunk + limbs - often present in several people frequenting the same establishment - self-limited in 7-10 days without antibiotic therapy in the vast majority of cases in immunocompetent people; fungal folliculitis (Malassezia - pityrosporum folliculitis): intense pruritus + monomorphic papulo-pustules on trunk + back + shoulders - aggravated by heat + perspiration + broad-spectrum antibiotics (disruption of cutaneous microbiota) + immunosuppressants - diagnosis: direct examination of pus (characteristic spores and short hyphae on KOH examination) - topical or oral antifungal treatment; pseudofolliculitis of the beard (PFB): ingrown hairs (pili recurvi) after shaving in men with curly hair (frequent in the black population) - papules + pustules + post-inflammatory hyperpigmentation + keloid scars - treatment: modification of shaving technique + electric razor + depilatory creams + topical retinoids + Nd:YAG laser
- Risk factors and predisposing conditions: skin trauma: shaving (micro-cuts + follicular irritation + hair manipulation) + hair removal (waxing + laser + tweezers) + friction from tight clothing or sports equipment + skin occlusion (bandages + dressings + non-breathable synthetic clothing); systemic factors: diabetes (impaired cutaneous immunity + hyperglycemia favoring bacterial and fungal growth) + obesity (maceration of folds + excessive sweating) + immunodepression (HIV + systemic corticosteroid therapy + chemotherapy + biotherapies) + chronic renal failure + iron-deficiency anemia; underlying dermatosis: atopic dermatitis (almost universal cutaneous colonization with S. aureus + altered skin barrier) + acne (Propionibacterium acnes + clogged follicles) + rosacea (Demodex); environmental factors: heat + humidity + excessive sweating (sports + manual labor) + exposure to mineral oils or industrial lubricants (occupational folliculitis - chloracne) + prolonged use of potent topical corticosteroids (steroid folliculitis - comedones + pustules without actual follicular inflammation); prolonged antibiotic therapy for acne: selection of Klebsiella pneumoniae + Proteus mirabilis + Enterobacter → Gram-negative folliculitis resistant to usual acne antibiotics → oral isotretinoin as treatment of choice
- Clinical diagnosis and further examinations: clinical diagnosis in the majority of cases: examination of lesion morphology + distribution + context (spa exposure + shaving + immunodepression + recent antibiotic therapy) - no additional examination required for simple, uncomplicated superficial folliculitis; bacterial culture of pus : indicated if multiple or extensive lesions + resistance to initial treatment + immunodepression + community MRSA context + frequent recurrences - swabbing of open pustule or fine-needle puncture of intact pustule - culture + antibiotic susceptibility test; mycological examination (KOH + fungal culture) : if Malassezia folliculitis suspected (trunk + back + intense pruritus + no response to antibiotics) or dermatophytosis (facial tinea barbae - deep ringworm); skin biopsy: reserved for atypical or chronic folliculitis - eosinophilic folliculitis (HIV + haemopathies) + decalvitating folliculitis + deep mycotic folliculitis; differential diagnoses: acne vulgaris (comedones + sebaceous cysts + facial + dorsal distribution) + miliaria (sudamina - obstruction of sweat glands - no central hair) + molluscum contagiosum (central umbilication + no hair) + chickenpox (central distribution + vesicles at different stages) + bullous impetigo (superficial bullae + no follicular centring).
Treatment
| Type of folliculitis | Treatment and Modalities | Duration, effectiveness and precautions |
|---|---|---|
| Mild superficial bacterial folliculitis S. aureus — few lesions |
The majority of mild superficial bacterial folliculitis (few lesions + non-recurrent + immunocompetent) heals spontaneously or with simple local care without systemic antibiotic therapy; local care: gentle cleansing twice daily with antiseptic soap (chlorhexidine 2-4 % or triclosan) - lukewarm water + gentle dabbing - no rubbing or handling of pustules; topical antibiotics (mild to moderate folliculitis - <10 lesions): mupirocin 2 % ointment (Bactroban): application × 2-3/d on lesions × 7-10 days - optimal coverage S. aureus SASM + partial SARM-AC coverage - 1st line for less extensive folliculitis; fusidic acid 2 % cream (Fucidin): application × 2-3/d × 7-10 days - effective on S. aureus - emerging resistance documented with prolonged or repeated use - do not use for long-term prevention; clindamycin 1 % gel or lotion: application × 2/d × 7-10 days - good anti-staphylococcal efficacy + partial MRSA-AC coverage - used in rotation with benzoyl peroxide (reduced resistance); benzoyl peroxide 2.5-5 % gel or lotion : application × 1-2/d - antibacterial + keratolytic + sebosuppressive properties - no selected bacterial resistance - particularly useful in recurrent + acneic folliculitis; hot compresses: 3-4 times/d × 10-15 min - reduce local inflammation + promote spontaneous drainage of pustules | Expected resolution of mild folliculitis with topical treatment: 7–14 days in the vast majority of cases — absence of scarring if no manipulation or deep extension; criteria for escalation to systemic antibiotic therapy: no response to topical treatment after 7–10 days + extension of the affected surface + numerous lesions (>10) + frequent recurrences (>3 episodes/6 months) + immunodeficiency + fever + adenopathy + poorly controlled diabetes; prevention of recurrences after healing: daily shower with antiseptic soap (chlorhexidine 2 %or 4 % ) × 5–7 days/month for maintenance + careful drying of folds + breathable cotton clothes + do not share towels + razors + avoid tight clothing in affected areas; recurrent folliculitis despite well-managed topical treatment → culture + antibiogram + nasal carriage screening for S. aureus + decolonization if carrier (see Furuncle/Anthrax sheet) |
| Extensive or recurrent bacterial folliculitis Systemic antibiotic therapy — MRSA coverage |
Systemic antibiotic therapy is indicated for extensive folliculitis (numerous lesions + large surface area) + recurrent + resistant to topical treatment + in immunocompromised patients; CA-MRSA coverage recommended as 1st line (significant prevalence in Canada - same reasoning as for boils): trimethoprim-sulfamethoxazole (TMP-SMX - Septra DS) 1 DS tablet × 2/d × 7-10 days: 1st line - MRSA + CA-MRSA coverage - CI: sulfonamide allergy + T1 and T3 pregnancy + GFR <15 + warfarin interaction; clindamycin 300 mg × 3/d × 7-10 days: alternative if TMP-SMX allergy - check sensitivity (D-zone test for inducible MRSA resistance) - risk of Clostridioides difficile - CI: history of pseudomembranous colitis; doxycycline 100 mg × 2/d × 7-10 days: alternative - effective on CA-MRSA in the majority of Canadian strains - CI: pregnancy + child <8 years; cefalexin 500 mg × 4/d × 7-10 days: active on MSSA only - reserved for folliculitis with culture confirming MSSA or areas with very low prevalence of CA-MRSA - insufficient if CA-MRSA suspected; total duration of treatment: 7-10 days for extensive simple folliculitis - 14 days if recurrent or if immunosuppressed - clinical reassessment at D7; adaptation according to culture: if culture confirms cefalexin-susceptible MRSA → cefalexin relay - if MRSA confirmed → TMP-SMX or clindamycin according to antibiogram | Chronic recurrent folliculitis despite well-administered antibiotic therapy - diagnostic approach: 1) rule out a non-bacterial cause (Malassezia + Demodex + steroid folliculitis + pseudofolliculitis) - 2) culture and antibiotic susceptibility testing of several lesions + nasal culture for S. aureus carriage - 3) laboratory workup: blood glucose + HbA1c (diabetes) + CBC (neutropenia) + immunoglobulins + HIV if risk factors - 4) if S. aureus nasal carriage confirmed → decolonization protocol (nasal mupirocin + chlorhexidine baths) - 5) if all causes ruled out + recurrent folliculitis → dermatology referral; recurrent scalp folliculitis (folliculitis decalvans - fibrosing variant): distinct entity - progressive destruction of follicles + scarring alopecia + tufts of clustered hair (tufted folliculitis) - culture often positive for S. aureus - treatment: rifampicin 300 mg × 2/d + clindamycin 300 mg × 2/d × 10-12 weeks (Rosen et al. protocol) + long-term maintenance doxycycline - dermatological referral mandatory |
| Hot tub folliculitis (Pseudomonas aeruginosa) Self-limiting — antibiotics rarely needed |
Spa folliculitis is caused by Pseudomonas aeruginosa proliferating in whirlpools, pools and jacuzzis with insufficient chlorine or pH levels - hot water + alkaline pH + jet pressure favor bacterial penetration of hair follicles; presentation: pruritic + erythematous papulo-pustules appearing 8-48h after exposure - distribution mainly on areas covered by bathing suit (trunk + buttocks + limbs) - sometimes accompanied by slight fever + malaise + Pseudomonas otitis externa (swimmer's ear) + mastalgia (sensitivity of nipples in women); evolution in immunocompetent patients : self-limited in 7-14 days without antibiotic therapy - spontaneous resolution in >90 % of cases; symptomatic treatment: cool compresses + oral antihistamines (cetirizine 10 mg/d or loratadine 10 mg/d) for pruritus + local antiseptic soap; systemic antibiotic therapy indicated only if: immunosuppression (HIV + chemotherapy + corticosteroids) + severe extension + persistent fever >5 days + severe Pseudomonas otitis externa; anti-Pseudomonas antibiotic therapy if indicated: ciprofloxacin 500 mg × 2/d × 5-7 days PO (only oral antibiotic effectively active on Pseudomonas) - levofloxacin 500 mg × 1/d × 5-7 days (alternative); public health declaration (DSPQ): clusters of spa folliculitis in commercial establishments (hotels + sports clubs + spas) must be reported for inspection of the water treatment system. | Preventing spa folliculitis: rigorous maintenance of whirlpools and jacuzzis - free chlorine residual: 3-10 mg/L (higher than for conventional pools, as heat + jets degrade chlorine more rapidly) - target pH: 7.2-7.6 - daily testing of chlorine and pH levels - draining + complete circuit cleaning every 3-4 weeks - water heat (>38°C) accelerates chlorine degradation and promotes Pseudomonas growth - shower before and after whirlpool use; in Quebec commercial establishments : pools and whirlpools are subject to the Règlement sur la qualité de l'eau des piscines (RQEP) standards - chlorine levels + pH + temperature + turbidity - periodic inspections by the Direction de santé publique; spa folliculitis and pregnancy: lesions generally self-limiting + no systemic treatment unless severe - no documented fetal risk from cutaneous Pseudomonas folliculitis - avoid whirlpools during pregnancy (risk of fetal hyperthermia independent of infection) |
| Fungal folliculitis (Malassezia - pityrosporum) Topical or oral antifungals |
Malassezia furfur folliculitis (formerly Pityrosporum ovale) is often overlooked and confused with acne vulgaris or bacterial folliculitis - it results from excessive proliferation of Malassezia yeast in hair follicles under favorable conditions (heat + perspiration + antibiotics + corticosteroids + immunosuppression); suggestive elements of the diagnosis: monomorphic papulo-pustules (all at the same stage - unlike polymorphic acne) + moderate to intense pruritus + predominantly upper trunk + back + shoulders + sometimes face and neck + markedly worsened by heat and perspiration + failure of usual antibiotic therapy (cefalexin + TMP-SMX) or worsening with broad-spectrum antibiotics; confirmatory diagnosis : direct KOH examination of the contents of a scraped pustule → characteristic round spores and short crescent hyphae («spaghetti and pellets» appearance) - Malassezia difficile culture (lipid-enriched medium required - Sabouraud + olive oil) - biopsy rarely required; topical treatment (1st line - mild to moderate forms): ketoconazole 2 % shampoo or cream: apply to trunk + affected areas × 1/d × 2-4 weeks - rinse after 5 min contact - maintenance: 1-2×/week; selenium sulfide 2.5 % lotion: apply × 1/d × 2 weeks - effective but unpleasant odor; ciclopirox 1 % gel or cream: apply × 2/d × 4 weeks; oral treatment (extensive or recurrent forms): itraconazole 200 mg/d × 7 days or 100 mg/d × 2 weeks - fluconazole 300 mg × 1 weekly dose × 4 weeks - efficacy >80 % with oral azoles | Maintenance after recovery from Malassezia folliculitis (prevention of frequent recurrences): antifungal shampoo or lotion (ketoconazole 2 % + zinc pyrithione + selenium sulfide) applied to trunk and scalp × 1-2/week as maintenance - particularly during hot, humid months + periods of heavy perspiration; predisposing factors to be corrected: glycemic control in diabetics + reduction in broad-spectrum antibiotics if possible + immediate shower after exercise + breathable cotton clothing + avoid occlusive greasy creams on trunk; Demodex folliculitis (follicular mite): very frequent on the face (nose + cheeks + forehead) - associated with rosacea + light phototype + elderly + immunodepression - treatment: ivermectin 1 % cream (Soolantra) × 1/d at bedtime × 3-4 months + metronidazole 0.75-1 % gel or cream + permetrin 5 % cream (weekly application) - oral ivermectin 200 µg/kg × 1 dose in 2 doses (D1 and D8) if extensive or refractory forms |
| Eosinophilic folliculitis and non-infectious folliculitis HIV + immunosuppression - specific approach |
Eosinophilic folliculitis (EF) is a distinct, non-infectious entity characterized by follicular eosinophilic infiltration - it presents in three main forms: classic EF (Ofuji disease - Japan - adults + intense pruritus + follicular urticarial plaques on face + trunk + limbs - blood eosinophilia); HIV-associated EF (most common in North America): severe, disabling pruritus + erythematous + urticarial papulo-pustules on face and trunk + CD4 usually <250-300/mm³ + eosinophilia + very high IgE - no infectious agent identified - mechanism: aberrant HIV-related immune response; FE associated with hematological malignancies (leukemias + lymphomas) and treatments (stem cell allografts); HIV-associated FE treatment: high-dose antihistamines (hydroxyzine 25-50 mg × 3/d + cetirizine 10 mg × 2/d) - potent topical corticosteroids (betamethasone 0.05 % + clobetasol 0.05 %) - narrow-band UV-B phototherapy (311 nm) × 2-3/week: most effective treatment - methoxsalen + UVA (PUVA) - oral isotretinoin 0.5 mg/kg/d × 4-6 months (proven efficacy but teratogenic - contraception mandatory) - indometacin 75 mg/d LP : NSAIDs with anti-eosinophilic action - partial response - optimize antiretroviral treatment: CD4 count rises → progressive reduction of EF in the medium term; steroid folliculitis: complication of potent topical corticosteroids applied long-term or systemic corticosteroids - monomorphic pustules + open comedones + follicular distribution - treatment: progressive discontinuation of corticosteroid + topical antibiotics if superinfection + topical retinoids | Follow-up of HIV-associated eosinophilic folliculitis: EF is chronic and recurrent - it generally follows the evolution of HIV immune status - immune recovery under effective antiretroviral therapy (ART) (CD4 >300/mm³) often leads to a reduction in the frequency and severity of episodes - but a syndrome of inflammatory immune reconstitution (SIRI) may paradoxically transiently aggravate EF in the first weeks of ART; important clinical documentation : any atypical folliculitis in an HIV+ patient (intense pruritus + possible FE + eosinophilia) or with skin lesions in a context of immunosuppression must be documented by skin biopsy + full dermatological work-up to exclude opportunistic skin infections (cryptococcosis + histoplasmosis + extensive molluscum contagiosum + shingles + kaposi) which may present as folliculitis; pseudofolliculitis of the beard (PFB): curative treatment: Nd:YAG 1064 nm laser (selective photolysis of the hair) - excellent, long-lasting results + reduction in post-inflammatory hyperpigmentation - 4-6 sessions 4-6 weeks apart - reference treatment for severe forms with hyperpigmentation + keloid scars |
ℹ️
Folliculitis or acne? - an essential clinical distinction: Bacterial folliculitis and acne vulgaris are often confused, but their treatments differ. Acne vulgaris is a multifactorial disease (hyperséborrhée + follicular hyperkeratinization + Cutibacterium acnes + inflammation) manifesting as open comedones (blackheads) + closed comedones (whiteheads) + papules + pustules + nodules + cysts — with facial, dorsal, and chest distribution. Bacterial folliculitis is a pure superficial infection, without comedones, more often itchy than painful, which can affect all hair-bearing areas of the body. Malassezia folliculitis (pityrosporum folliculitis) is particularly often confused with acne on the back — it does not respond to standard acne treatments (tetracyclines + adapalene) but does respond to antifungals. A dermatological evaluation is recommended for any «acne» on the back that is resistant to standard treatments.
Signs requiring medical attention
Widespread folliculitis + fever + chills + swollen lymph nodes Severe skin infection or early onset of skin sepsis → urgent medical consultation on the same day.
Untreated facial folliculitis that spreads, becomes very painful, and develops deep induration → inflammation into a boil or cellulitis — never manipulate lesions in the nasolabial triangle without medical advice.
Recurrent folliculitis in a diabetic or immunocompromised patient, resistant to two courses of antibiotics → Medical consultation for culture + etiological assessment + reassessment of maintenance treatment.
Consult at Clinique Omicron
The doctors at Clinique Omicron diagnose and treat all forms of folliculitis: bacterial folliculitis, hot tub folliculitis, fungal folliculitis, and recurrent folliculitis. They prescribe appropriate topical and systemic treatments, perform necessary microbiological collections, and refer to a dermatologist for atypical or chronic forms. Consultations are available at several service locations in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not substitute for professional medical advice from a qualified healthcare provider. Folliculitis that worsens, spreads, or does not respond to usual treatment should be evaluated by a doctor.
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