Jock itch (also known as tinea cruris) is a common fungal infection that affects the skin of the inner thighs, buttocks and genitals. The fungus that causes jock itch thrives in warm, moist areas. As a result, it causes an itchy, red, often ring-shaped rash in these warm, moist areas of the body.

Jock itch (tinea cruris) is a surface (superficial) fungal infection of the skin on either side of the body where the thigh joins the abdomen, known as the groin. It is often spread to the groin from tinea infection on the feet (tinea pedis or athlete's feet).

Jock Itch Causes

Jock itch is caused by a fungus that lives on your skin. The name of the fungus is Tinea cruris, and is related to the athlete's foot fungus. Jocks aren't the only ones who get jock itch - men who sweat a lot can also get it, and sometimes women too. This fungus likes to grow and live in the warm, moist parts of the genital area, particularly the insides of the thighs. The rash makes the area itch, causes the skin to become red and sometimes crack or peel.

Jock itch is caused by a fungus, often the same one that causes athlete's foot. Sometimes it is transferred by a towel used to dry the feet and then the groin area.

Jock Itch Symptoms

The acute infection begins with an itchy area of redness about a half-inch across. The area may enlarge, and other sores may develop in no particular pattern. The rash appears as raised red plaques (platelike areas) with sharp borders. The border may exhibit tiny pimples or even pustules with central areas that are reddish and dry with small scales.

Jock Itch Diagnosis

The best way to diagnose tinea cruris is to look for hyphae under the microscope, a KOH test. The skin is scraped with a scalpel or glass slide causing dead skin cells to fall off onto a glass slide. A few drops of Potassium hydroxide (KOH) are added to the slide and the slide is heated for a short time. The KOH dissolves the material binding the skin cells together releasing the hyphae, but it does not distort the cell or the hyphae. Special stains such as Chlorazol Fungal Stain, Swartz Lamkins Fungal Stain, or Parker's blue ink can be used to help visualize the hyphae better.

Jock Itch Treatment

1. Wash the rash with soap and water. Gently remove any pieces of dried skin, and spread an antifungal cream over the rash. Apply the cream beyond the edge of the rash.

2. Jock itch is treated with one of two types of antifungal medications — azoles or allylamines. Generally, allylamines require a shorter treatment time, while azoles are less expensive but require longer treatment time.

3. For a mild case of jock itch, your doctor may suggest first using an over-the-counter antifungal ointment, lotion, powder or spray.

4. If you have jock itch and athlete's foot, you should treat both to prevent re-infecting your groin when you put on your underwear.