Tinea cruris is the name used for infection of the groin with a dermatophyte fungus. It is most often seen in adult men. Tinea cruris is commonly known as jock itch.
In different parts of the world, different species cause tinea cruris. In New Zealand, Trichophyton rubrum and Epidermophyton floccosum are the most common causes. Infection often comes from the feet (tinea pedis) or nails (tinea unguium) originally, spread by scratching or the use of an infected towel.
The appearance is similar to ringworm (tinea corporis). The rash has a scaly raised red border that spreads down the inner thighs from the groin or scrotum. Tinea cruris may form ring-like patterns on the buttocks. It is not often seen on the penis or vulva or around the anus. Tinea cruris can be very itchy.
Tinea cruris can be confused with other forms of intertrigo such as:
Tinea cruris quite often recurs after apparently successful treatment. To reduce the chance of reinfection:
- Treat the feet if tinea pedis is present.
- Dry the groin carefully after bathing using a separate towel.
- Do not share towels, sheets or personal clothing.
- Avoid wearing occlusive or synthetic clothing.
- If you are overweight, try to lose weight to reduce chafing and sweating.
Diagnosis of tinea cruris
The diagnosis of tinea cruris is confirmed by microscopy and culture of skin scrapings.
Treatment of tinea cruris
Tinea cruris is usually treated with topical antifungal agents. Sometimes hydrocortisone is added, for faster relief of itch. Topical steroids should not be used on their own. If the treatment is unsuccessful, oral antifungal medicines may be considered, including terbinafine and itraconazole.
On DermNet NZ:
- Introduction to fungal infections
- Laboratory tests for fungal infections
- Treatment of fungal infections
- Auckland Sexual Health Service
- Tinea cruris – Medscape Reference
- Jock Itch – emedicinehealth
- Patient information: Ringworm, athlete’s foot, and jock itch (The Basics) – UpToDate (for subscribers)
- Patient information: Ringworm (including athlete's foot and jock itch) (Beyond the Basics) – UpToDate (for subscribers)
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