(See also Overview of Fungal Skin Infections.)
Tinea cruris is a type of dermatophytosis. Tinea cruris is primarily caused by Trichophyton.
This infection is much more common among men because moisture can get trapped between the scrotum and thigh. Tinea cruris develops most frequently in warm weather or when wearing wet and tight clothing. People who are obese are at risk because their skinfolds trap moisture.
The infection begins in the skinfolds of the genital area and can spread to the upper inner thighs and may occur on both sides. Usually the scrotum is not affected or is only slightly affected. The rash has a scaly, pink border. Tinea cruris can be quite itchy and may be painful. This infection often recurs, particularly among people who have onychomycosis or athlete's foot (tinea pedis), because fungi can spread from those infections to the groin. Flare-ups occur more often during the summer.
The diagnosis of tinea cruris is usually obvious to doctors based on a physical examination.
If the diagnosis is not obvious, doctors may do a skin scraping and examine it under a microscope to be sure that the rash is caused by a fungus.
Treatment of tinea cruris involves an antifungal cream or lotion (such as miconazole, naftifine, ketoconazole, or clotrimazole). (See also table Some Antifungal Drugs Applied to the Skin (Topical Drugs).)
Antifungal drugs taken by mouth (such as itraconazole or terbinafine) may be needed in people who have infections that are widespread or cause inflammation or infections that are difficult to heal.