Dermatology
Tinea & Fungal Infections
Library·Dermatology·Tinea & fungal
Don't miss
- Tinea incognito - bizarre pattern after topical steroid; confirm before treating
- Tinea capitis with kerion - boggy inflammatory mass, oral therapy
- Cellulitis on top of tinea pedis - common entry point
- Eczema or psoriasis misdiagnosed as tinea (no advancing edge, no central clearing)
First-line
- Pedis / corporis / cruris
- Topical terbinafine or azole (clotrimazole) for 2-4 weeks
- Capitis
- Always oral - griseofulvin first-line, terbinafine alternative. No school exclusion
- Onychomycosis
- Confirm with mycology first. Oral terbinafine 250 mg/day - 6 weeks (fingernails) or 12 weeks (toenails)
- Pityriasis versicolor
- Selenium sulfide or ketoconazole shampoo applied to skin × 10 min, rinse
Refer when
- Recalcitrant tinea unresponsive to optimised therapy
- Tinea capitis with kerion or extensive disease
- Recurrent onychomycosis
- Diagnostic uncertainty after KOH/culture
Tell the patient
- Treatment takes weeks - keep going past when it looks gone
- Don't share towels, shoes, or hats; treat household contacts if scalp involvement
- Nail treatment is months - LFT before terbinafine if you have liver issues
- Pigment changes after pityriasis versicolor take months to fade - that is normal
Superficial fungal infections are caused predominantly by dermatophytes (tinea) or yeasts (Candida, Malassezia). Distinguishing them clinically matters because the treatment differs. Tinea presents with a scaling, usually annular, advancing edge; candidal intertrigo is beefy-red with satellite pustules in moist folds; pityriasis versicolor (Malassezia) causes hypo- or hyperpigmented, finely scaling macules on the trunk - often noticed as patches that fail to tan.
❍ Treatment by site
- Tinea pedis (athlete's foot) - the most common fungal infection. Interdigital maceration and scaling, typically between the fourth and fifth toes. Can extend to a moccasin distribution on the sole. Treat with topical terbinafine or an azole (clotrimazole) for 2-4 weeks. Dryness between toes and breathable footwear are essential adjuncts.
- Tinea corporis / cruris - annular plaque with advancing scaly edge and central clearing. Tinea cruris affects the groin (sparing the scrotum, which distinguishes it from candidal intertrigo). Topical azole or terbinafine for 2-4 weeks. Warn patients it takes time.
- Tinea capitis - predominantly in children; presents as scaly scalp patches with variable hair loss and, in severe cases, a boggy inflammatory mass (kerion). Requires oral therapy - griseofulvin is first-line where available; terbinafine is an alternative. Scalp brushings or hair clippings for mycology culture before treating if the diagnosis is uncertain. School exclusion is not required; advise avoiding shared hats and combs.
- Onychomycosis (tinea unguium) - subungual thickening, discolouration, and onycholysis, usually toenails. Confirm with mycology before treating - nail dystrophy has many non-fungal causes and oral antifungal therapy is prolonged. Oral terbinafine 250 mg daily for 6 weeks (fingernails) or 12 weeks (toenails) is the most effective regimen.1 Hepatotoxicity is rare but warrants baseline LFTs in patients with liver disease or on hepatotoxic medications.
- Pityriasis versicolor - caused by Malassezia furfur. Trunk and upper arms; hypo- or hyperpigmented patches with fine scale. Topical selenium sulfide shampoo (applied to affected areas for 10 minutes, then rinsed) or ketoconazole shampoo are first-line. Oral itraconazole is effective for extensive or recurrent disease. Warn that pigmentation changes normalise slowly after treatment.
❍ Diagnosis and when to use oral therapy
Most tinea is diagnosed clinically. Where the presentation is atypical or treatment has failed, skin scrapings, nail clippings, or hair samples sent for microscopy and culture are invaluable. Scrapings from the active scaling edge (not the central clearing) give the best yield. Note: topical steroids applied to an undiagnosed tinea will temporarily suppress the appearance but allow the fungus to continue spreading - the pattern that results ("tinea incognito") is often bizarre and easily missed.
Oral antifungals are indicated for: tinea capitis (always), onychomycosis (usually), extensive or recalcitrant tinea corporis/cruris/pedis, and pityriasis versicolor that has failed topical treatment. Terbinafine is the drug of choice for dermatophyte infections. Itraconazole is preferred for yea