How do I know if my nail problem is fungal or something else?

Nail problems are commonly not fungal. Around half of all nail dystrophy — thickened, discoloured, or crumbling nails — is caused by psoriasis, trauma, lichen planus, or normal ageing rather than fungus. The only way to know is to confirm with laboratory testing: a nail clipping sent for KOH microscopy and fungal culture. This matters because treatment requires terbinafine tablets daily for 12 weeks — a long course with some monitoring requirements — and there is no point taking it if the cause is not fungal. Your GP can collect the clipping, send it to the laboratory (Medicare-rebated), and review the result before prescribing.

What is the difference between athlete's foot and tinea cruris?

Athlete's foot (tinea pedis) affects the skin of the feet — most commonly the spaces between the toes (interdigital), which become itchy, peeling, and sometimes macerated. It can also affect the sole in a powdery moccasin distribution. Tinea cruris ('jock itch') affects the groin and inner thighs. A key distinguishing feature of tinea cruris is that it spares the scrotum — if the scrotum is involved, candida is more likely. Both conditions commonly co-exist, and athlete's foot is often the reservoir for groin tinea, so treating both at the same time helps prevent recurrence. Both respond to antifungal cream. Both are more common in warm, humid conditions and with occlusive clothing or footwear.

What is tinea incognito and how does it happen?

Tinea incognito occurs when a tinea infection is misidentified as eczema or psoriasis, and a corticosteroid (steroid) cream is applied. Steroid cream suppresses the inflammation that produces tinea's typical appearance — the scaly, raised, active border — so the rash temporarily improves or changes character. The fungus, however, keeps growing. When the steroid is stopped, or as time passes, the infection spreads and becomes extensive, atypical, or difficult to identify. It is a common pitfall in general practice. If you have a persistent rash that has changed character after using steroid cream, see your GP for a skin scraping and KOH examination before continuing any treatment.

My child has bald patches and scaly scalp. Could this be tinea capitis?

Yes — tinea capitis (scalp ringworm) is one of the most important causes of patchy hair loss with scaling in children, particularly in urban Australian communities where Trichophyton tonsurans is now circulating. The fungus invades the hair shaft itself, which means antifungal cream applied to the scalp does not reach it and will fail. Oral antifungal tablets — terbinafine for Trichophyton species, or griseofulvin for Microsporum species — are always necessary for tinea capitis. A kerion, which is a boggy, inflamed, tender scalp swelling, is a severe form requiring prompt treatment. Your child's GP can take a scalp scraping or hair sample for laboratory confirmation and prescribe the appropriate oral antifungal.

How long does it take for nail fungus to clear after treatment?

Even with successful treatment with terbinafine tablets, nail fungus takes a long time to look better because nails grow slowly. Toenails grow approximately 1–2 mm per month; a complete replacement of the toenail takes 12–18 months. So even after completing the 12-week course of tablets — during which time the fungus is killed — the nail will still look abnormal while it grows out. You may not see a clearly improving nail for 6–9 months after finishing treatment. Fingernails grow faster and improve more quickly. Cure rates with terbinafine are around 60–70%; recurrence within two years occurs in approximately 20–30% of cases, often because of reinfection from athlete's foot not treated at the same time.

What can I do to prevent tinea pedis from coming back?

Recurrence is common because the fungus lives in shoes, socks, and shared surfaces. Effective prevention: dry your feet thoroughly between the toes after bathing; wear moisture-wicking socks (wool or synthetic, not cotton); rotate your shoes so they dry completely between wears; use antifungal powder (tolnaftate or miconazole) in shoes regularly; avoid walking barefoot in communal shower areas, pool surrounds, and gyms; wear thongs (flip-flops) in shared changing rooms. If you have onychomycosis, treat athlete's foot simultaneously — the nails act as a reservoir that reinfects the skin. Sun-drying shoes helps. Some people need ongoing antifungal powder use long-term.

Tinea and onychomycosis

Tinea and onychomycosis: athlete's foot, nail fungus, and ringworm in AU

By Dr HB Lo, FACRRM Reviewed 24 July 2026 10 min read

Tinea is a superficial dermatophyte infection of skin, nails, or hair. Tinea pedis (athlete's foot) affects around 10% of Australian adults; onychomycosis (nail fungus) affects up to 30% of people over 60.

Skin tinea responds to antifungal cream for one to four weeks. Nail tinea requires laboratory confirmation first — around half of nail dystrophy is not fungal — then terbinafine tablets for 12 weeks. Tinea capitis (scalp ringworm) in children always needs oral treatment; topical cream alone fails because the fungus lives inside the hair shaft. Tinea incognito (altered appearance from misapplied steroid cream) is a common pitfall.

Tinea: the family of fungal infections you already know

Tinea is the name for a family of superficial fungal infections caused by organisms called dermatophytes — mainly from the genera Trichophyton, Microsporum, and Epidermophyton. Despite its many common names — athlete’s foot, jock itch, ringworm, nail fungus — they all share the same underlying biology: dermatophytes digest keratin, the protein in skin, nails, and hair, and thrive in warm, moist environments.

Therapeutic Guidelines (eTG) and the Australasian College of Dermatologists recognise tinea pedis (feet) as the most common presentation, affecting roughly 10% of Australian adults at any time. Onychomycosis (nail fungus) affects around 10% of adults overall and up to 30% of people over 60. Tinea is largely harmless but genuinely uncomfortable — it itches, can crack and bleed, is cosmetically distressing, and when it affects nails, it can cause pain in footwear.

Understanding which pattern you have guides treatment. Skin tinea responds to cream. Nail tinea needs tablets — but only after laboratory confirmation, because half of all nail dystrophy is not fungal.

A. Core clinical — the Australian general practice framework

The patterns of tinea

Tinea pedis (athlete’s foot) is the most common form. Three main patterns:

Interdigital — white, moist, peeling, or cracked skin between the toes, most often between the fourth and fifth toes. Itching is the dominant symptom.
Moccasin — diffuse dry, powdery scaling over the sole and sides of the foot. Less itchy but more extensive.
Vesicular — fluid-filled blisters on the arch or sides of the foot, often intensely itchy, that burst and scale.

Tinea pedis acts as a portal for cellulitis, particularly in people with diabetes or leg swelling, because the skin cracks allow bacterial entry. It also acts as the main reservoir for toenail onychomycosis — the nail picks up the fungus from the surrounding skin.

Tinea cruris (jock itch) affects the groin and inner thighs, producing an itchy rash with a well-defined, slightly raised, scaly active border that advances outward while the central skin clears. A key distinguishing feature: tinea cruris spares the scrotum. Scrotal involvement suggests candida rather than tinea. Tinea cruris and tinea pedis frequently co-exist; treating both prevents reinfection through the shared dermatophyte reservoir.

Tinea corporis (ringworm) — despite the name, no worm is involved. This is a classic circular or ring-shaped rash on the body with a scaly, raised active border and central clearing. It is often picked up from animal contact (cats and dogs carry Microsporum canis) or from another person. Tinea incognito — the modified form produced by steroid cream — loses the ring appearance and becomes an irregular, spreading rash.

Tinea capitis (scalp ringworm) occurs primarily in children and requires special attention. The fungus invades the hair shaft itself, producing patchy hair loss and scaling. A kerion — a boggy, inflamed, tender scalp mass — represents an intense inflammatory response and needs prompt oral treatment. Topical antifungal cream alone is always inadequate for tinea capitis because it cannot penetrate the hair shaft. Oral antifungal tablets are essential.

Tinea unguium / onychomycosis (nail fungus) causes nail thickening, discolouration (white, yellow, or brown), separation of the nail from its bed (onycholysis), and crumbling subungual debris. The most common form starts at the free edge and side of the nail (distal-lateral subungual). Critically, around half of all nail dystrophy is not fungal — psoriasis, nail trauma, lichen planus, and normal ageing all produce similar appearances. Confirming the diagnosis before committing to a long course of tablets is not optional.

Tinea manuum affects the hand, typically one hand only (“two foot one hand” is a classic presentation). Tinea barbae affects the bearded area and is often zoonotic. Tinea faciei involves the face and is frequently misidentified — particularly after corticosteroid cream application — as eczema or seborrhoeic dermatitis.

Pityriasis versicolor is caused by Malassezia (not a dermatophyte — strictly speaking, not tinea) and produces hypopigmented or hyperpigmented patches on the trunk and upper back, often most visible after sun exposure. Treatment differs from standard tinea.

Investigations

Skin scraping and KOH microscopy — a quick bedside test where skin scale is collected on a glass slide, treated with potassium hydroxide solution, and examined under the microscope for fungal hyphae. Provides rapid confirmation.

Fungal culture (Sabouraud agar) — identifies the species, guides treatment where species matters (e.g. Microsporum vs Trichophyton in tinea capitis). Takes 2–3 weeks. MBS item 69384 range applies.

Nail clipping with KOH and culture — essential before prescribing oral antifungals for onychomycosis. The clipping should include subungual debris. Without confirmation, you risk a 12-week course of terbinafine for a problem that is not fungal.

Pre-oral antifungal baseline tests: LFTs (item 66512) baseline before terbinafine or itraconazole (rare but recognised hepatotoxicity); FBC; pregnancy test; drug interaction review (especially for itraconazole, which is a CYP3A4 inhibitor).

Wood’s lamp — ultraviolet light examination; useful for Microsporum species (green fluorescence) but most Trichophyton species do not fluoresce, limiting its utility.

Treatment overview

Per eTG Dermatology and AMH:

Topical antifungals (for limited skin tinea of the feet, groin, and body):

Agent	Schedule	Duration
Terbinafine 1% cream	Twice daily	1–2 weeks
Clotrimazole 1% or miconazole 2%	Twice daily	4 weeks
Ketoconazole 2% cream	Once or twice daily	4 weeks

Terbinafine cream works fastest and has the shortest required course. Imidazoles (clotrimazole, miconazole, ketoconazole) need a longer application period but are widely available over the counter.

Oral antifungals are required for: onychomycosis (nail), tinea capitis (scalp), and extensive or treatment-resistant skin tinea.

Indication	Drug	Dose and duration
Toenail onychomycosis	Terbinafine	250 mg daily × 12 weeks
Fingernail onychomycosis	Terbinafine	250 mg daily × 6 weeks
Tinea capitis (Trichophyton)	Terbinafine	250 mg daily × 4 weeks (paediatric weight-based dosing)
Tinea capitis (Microsporum)	Griseofulvin	20 mg/kg/day × 6–8 weeks
Extensive skin tinea	Terbinafine	250 mg daily × 2–4 weeks

Itraconazole pulse therapy (200 mg twice daily for 1 week per month, repeated 2 cycles for fingernails and 3 for toenails) is an alternative for nail onychomycosis, particularly when drug interactions or intolerance preclude terbinafine. However, itraconazole is a CYP3A4 inhibitor with significant interactions — statins (particularly simvastatin and lovastatin), warfarin, calcium channel blockers, and immunosuppressants. A thorough drug interaction check is essential before prescribing.

B. Evidence on common controversies

Confirm before you treat nail fungus

The most important principle in onychomycosis management is not which antifungal to use — it is confirming that the problem is fungal before committing to treatment. Studies and eTG guidance consistently report that approximately 50% of nail dystrophy referred as presumptive onychomycosis is non-fungal on culture. Psoriasis, trauma from footwear, lichen planus, ageing changes, and subungual melanoma (a serious diagnosis not to miss) all mimic fungal nail disease.

The consequences of empiric treatment include: a 12-week course of terbinafine (with LFT monitoring obligations, potential taste disturbance, and rare hepatotoxicity) for a condition that will not respond; PBS authority prescribing problems (the authority requires documented mycological confirmation); and, importantly, delayed diagnosis of the real cause, including the rare but serious subungual melanoma. A pigmented longitudinal streak under the nail, or pigment spreading to the nail fold (Hutchinson sign), must be referred for biopsy — do not treat as fungus.

Terbinafine vs itraconazole for nails

Terbinafine achieves higher mycological cure rates (~60–70% for toenails) than itraconazole pulse therapy (~55–65%) and has fewer serious drug interactions. The evidence from eTG and AMH supports terbinafine as first-line. Itraconazole pulse is an alternative when terbinafine is contraindicated or not tolerated.

Topical lacquers for nails

Topical antifungal nail lacquers — amorolfine 5% and ciclopirox — have very modest cure rates (approximately 10–15% mycological cure for onychomycosis). They may be appropriate for mild, distal disease involving only the very tip of the nail where penetration is possible, or when the patient declines oral treatment. They are not a substitute for oral terbinafine in established onychomycosis.

C. Prevention and adjunctive measures

Dermatophytes are extremely common in the environment. Preventing recurrence is as important as treating the active infection.

Footwear hygiene is the most effective single measure for tinea pedis and onychomycosis recurrence prevention:

Dry feet thoroughly between the toes after bathing (pat — don’t rub, as maceration aids fungal entry)
Rotate shoes so each pair has at least 24 hours to dry completely
Use antifungal foot powder (tolnaftate or miconazole) inside shoes regularly
Wear moisture-wicking socks; change after exercise
Wear thongs or sandals in communal changing areas, pool surrounds, and gym showers
Sun-dry shoes periodically — ultraviolet light reduces fungal load

Treat coexistent tinea pedis when treating onychomycosis. Failure to do so is the single biggest driver of onychomycosis recurrence. The periungual skin is the reservoir; if it is not cleared, the nails will be reinfected.

Shampoo adjunct in tinea capitis. Selenium sulfide or ketoconazole shampoo used twice weekly reduces scalp spore shedding during the oral antifungal course. It does not replace oral treatment but reduces transmission to household contacts. Household contacts of a child with tinea capitis should have their scalps examined.

D. Australian operations — prescribing and access

PBS authority for onychomycosis oral antifungals requires documented mycological confirmation (KOH microscopy positive or culture positive). Document the laboratory result in the medical record before prescribing. Terbinafine and itraconazole are both Authority Required for onychomycosis on the PBS. Griseofulvin requires Authority for paediatric tinea capitis. Topical antifungals (terbinafine cream, clotrimazole, miconazole, ketoconazole, bifonazole) are general schedule — available over the counter without a prescription. Amorolfine 5% nail lacquer is also available without a prescription.

MBS items: Standard GP consultations 23, 36, 44; pathology for skin scraping and nail clipping item 69384 range; LFTs 66512; FBC 65070. The GPCCMP items 965/967 apply to patients with chronic recurrent tinea in the context of diabetes, peripheral vascular disease, or immunocompromise — chronic care planning including podiatry referral for nail management.

Telehealth limitation: In-person examination is required for skin scraping and nail clipping collection. Tinea assessment via telehealth is possible for history and decision-making, but sample collection for laboratory confirmation requires a face-to-face attendance.

E. Special populations

People with diabetes or peripheral vascular disease face greater complications from tinea — cracked skin from tinea pedis is a common portal for lower limb cellulitis and can contribute to diabetic foot complications. Annual podiatry review and footwear assessment are part of best practice diabetes care. Treat tinea actively in this group; don’t wait.

Immunocompromised patients (HIV, solid organ transplant, haematological malignancy, high-dose corticosteroids) may develop extensive, atypical, or refractory tinea, including with non-dermatophyte fungi such as Scopulariopsis brevicaulis or Fusarium species that do not respond to standard antifungals. Lower the threshold for dermatology referral and specialist-guided treatment.

Pregnancy: Topical antifungals (terbinafine cream, clotrimazole, miconazole) are considered acceptable for skin tinea during pregnancy. Oral terbinafine (Category B1, limited data) and oral itraconazole (Category C) should ideally be deferred until after pregnancy and breastfeeding. Oral griseofulvin is a teratogen — absolutely contraindicated in pregnancy. Defer onychomycosis treatment until after delivery.

Children with tinea capitis: The child’s school or childcare centre should be notified. Children can attend school while on treatment but should avoid sharing hats, combs, and pillow cases. Household contacts — particularly siblings — should have scalps checked.

ATSI communities: Higher rates of tinea capitis have been reported in some Aboriginal communities, partly related to Trichophyton violaceum. Secondary streptococcal infection of fungal skin lesions is a recognised complication with implications for rheumatic fever risk. Prompt treatment and community health worker engagement are important.

When to escalate

Refer to or urgently discuss with a dermatologist when:

Treatment has failed after two appropriately prescribed courses
Tinea is extensive, involving the face, or occurring in an immunocompromised person
A kerion is present in a child — this is a same-week referral
Non-dermatophyte fungal infection is suspected (nails that grew on culture with organisms other than standard dermatophytes)
There is a pigmented longitudinal streak under a nail or pigment in the nail fold (Hutchinson sign) — refer urgently for consideration of subungual melanoma
Complex drug interactions preclude standard antifungal therapy

Seek same-day medical review when:

A skin tinea lesion is spreading rapidly despite treatment
Signs of secondary bacterial infection appear — increasing redness, warmth, pus, fever, red streaking — especially in the lower legs (cellulitis from tinea pedis portal)

What this article is and is not

This is general health information drawn from Therapeutic Guidelines (eTG), the Australasian College of Dermatologists, Australian Medicines Handbook (AMH), and NPS MedicineWise. It is not personal medical advice and does not create a doctor–patient relationship. Diagnosis and treatment decisions — particularly before starting oral antifungal tablets — should be made with your own GP.

For AU consumer information: HealthDirect — Tinea, Better Health Channel — Tinea.

Sources cited

Frequently asked questions

How do I know if my nail problem is fungal or something else?

Nail problems are commonly not fungal. Around half of all nail dystrophy — thickened, discoloured, or crumbling nails — is caused by psoriasis, trauma, lichen planus, or normal ageing rather than fungus. The only way to know is to confirm with laboratory testing: a nail clipping sent for KOH microscopy and fungal culture. This matters because treatment requires terbinafine tablets daily for 12 weeks — a long course with some monitoring requirements — and there is no point taking it if the cause is not fungal. Your GP can collect the clipping, send it to the laboratory (Medicare-rebated), and review the result before prescribing.
What is the difference between athlete's foot and tinea cruris?

Athlete's foot (tinea pedis) affects the skin of the feet — most commonly the spaces between the toes (interdigital), which become itchy, peeling, and sometimes macerated. It can also affect the sole in a powdery moccasin distribution. Tinea cruris ('jock itch') affects the groin and inner thighs. A key distinguishing feature of tinea cruris is that it spares the scrotum — if the scrotum is involved, candida is more likely. Both conditions commonly co-exist, and athlete's foot is often the reservoir for groin tinea, so treating both at the same time helps prevent recurrence. Both respond to antifungal cream. Both are more common in warm, humid conditions and with occlusive clothing or footwear.
What is tinea incognito and how does it happen?

Tinea incognito occurs when a tinea infection is misidentified as eczema or psoriasis, and a corticosteroid (steroid) cream is applied. Steroid cream suppresses the inflammation that produces tinea's typical appearance — the scaly, raised, active border — so the rash temporarily improves or changes character. The fungus, however, keeps growing. When the steroid is stopped, or as time passes, the infection spreads and becomes extensive, atypical, or difficult to identify. It is a common pitfall in general practice. If you have a persistent rash that has changed character after using steroid cream, see your GP for a skin scraping and KOH examination before continuing any treatment.
My child has bald patches and scaly scalp. Could this be tinea capitis?

Yes — tinea capitis (scalp ringworm) is one of the most important causes of patchy hair loss with scaling in children, particularly in urban Australian communities where Trichophyton tonsurans is now circulating. The fungus invades the hair shaft itself, which means antifungal cream applied to the scalp does not reach it and will fail. Oral antifungal tablets — terbinafine for Trichophyton species, or griseofulvin for Microsporum species — are always necessary for tinea capitis. A kerion, which is a boggy, inflamed, tender scalp swelling, is a severe form requiring prompt treatment. Your child's GP can take a scalp scraping or hair sample for laboratory confirmation and prescribe the appropriate oral antifungal.
How long does it take for nail fungus to clear after treatment?

Even with successful treatment with terbinafine tablets, nail fungus takes a long time to look better because nails grow slowly. Toenails grow approximately 1–2 mm per month; a complete replacement of the toenail takes 12–18 months. So even after completing the 12-week course of tablets — during which time the fungus is killed — the nail will still look abnormal while it grows out. You may not see a clearly improving nail for 6–9 months after finishing treatment. Fingernails grow faster and improve more quickly. Cure rates with terbinafine are around 60–70%; recurrence within two years occurs in approximately 20–30% of cases, often because of reinfection from athlete's foot not treated at the same time.
What can I do to prevent tinea pedis from coming back?

Recurrence is common because the fungus lives in shoes, socks, and shared surfaces. Effective prevention: dry your feet thoroughly between the toes after bathing; wear moisture-wicking socks (wool or synthetic, not cotton); rotate your shoes so they dry completely between wears; use antifungal powder (tolnaftate or miconazole) in shoes regularly; avoid walking barefoot in communal shower areas, pool surrounds, and gyms; wear thongs (flip-flops) in shared changing rooms. If you have onychomycosis, treat athlete's foot simultaneously — the nails act as a reservoir that reinfects the skin. Sun-drying shoes helps. Some people need ongoing antifungal powder use long-term.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.

T1 AU primary 9 sources