Overview
Ringworm (tinea) is a fungal skin infection, not caused by a worm. It produces a characteristic ring-shaped, red, scaly, and itchy rash that spreads outward from a clear centre. Different types affect different body areas: tinea corporis (body), tinea capitis (scalp), tinea cruris (groin, also called jock itch), and tinea pedis (feet, also called athlete's foot).
How common is it?
Tinea infections are among the most common skin conditions worldwide, affecting around 20 to 25% of people at some point. Tinea capitis (scalp ringworm) is most prevalent in children. Athlete's foot affects around 15 to 20% of adults.
Causes and risk factors
Dermatophyte fungi (Trichophyton, Microsporum, Epidermophyton species) infect keratin in skin, hair, and nails, living on the outer layers without invading deeper tissues.
Common risk factors
- Contact with infected person, animal, soil, or shared items (towels, combs, sports equipment)
- Warm, humid conditions promoting fungal growth
- Participation in contact sports (wrestling, football)
- Walking barefoot in communal areas
- Excessive sweating
- Weakened immune system or diabetes
- Close contact with infected pets (especially cats)
Symptoms
- Red, scaly, ring-shaped patches with clearer centres on body skin
- Itching at the affected site
- Scalp: scaly patches with hair loss, sometimes with pustules (kerion)
- Groin: red, itchy rash in the groin folds
- Feet: scaling, maceration between toes, itching, sometimes blisters (athlete's foot)
- Nails: thickened, discoloured, crumbling
When to see a doctor
See a GP if ringworm involves the scalp (requires oral antifungal), does not respond to 2 to 4 weeks of over-the-counter treatment, or if there are signs of secondary bacterial infection.
Diagnosis
Usually clinical. Skin scraping or hair/nail sampling sent for microscopy and culture if uncertain. Scalp ringworm may fluoresce green under Wood's lamp for some species.
Treatments
Topical antifungal creams
Terbinafine 1% cream applied twice daily for 1 to 2 weeks is the most effective topical agent. Clotrimazole or miconazole for 2 to 4 weeks are alternatives. Continue for 1 to 2 weeks after the rash clears.
Oral antifungals
Griseofulvin or terbinafine tablets are required for scalp ringworm (tinea capitis) and nail infection. Scalp infection: griseofulvin 6 to 8 weeks; nail infection: terbinafine 6 weeks (fingernails) to 12 weeks (toenails).
Selenium sulphide or ketoconazole shampoo
Adjunct to oral antifungals in tinea capitis to reduce spread to other household members.
Self-care and lifestyle
- Do not share towels, hairbrushes, or combs with infected individuals
- Treat infected pets promptly (veterinary advice)
- Keep affected skin dry and well ventilated
- All household members and classmates should be checked for scalp ringworm
Prevention
Avoid contact with infected animals and people. Wear flip-flops in communal areas. Keep skin dry. Treat athlete's foot promptly to prevent nail spread.