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).
As implied by the name, jock itch typically affects athletes because of how much they sweat and a large amount of time they spend in locker rooms, where fungi flourish. The rash shows up as red bumps, sometimes with cracking or peeling skin, but always itchy.
Fungi thrive in warm, moist areas such as steamy shower rooms among damp towels, sweaty workout clothes, and wet floors. Since jock itch occurs in a dark, warm area of the body there is no question why jock itch is so common and spreads so quickly. In addition to the discomfort caused by this fungus, it is important to begin effective treatment as soon as possible to avoid spreading the rash to other areas of your body and possibly to other people.
Athlete’s foot is caused by the same fungus as jock itch, so it is easy to get athlete’s foot and jock itch at the same time. If your foot touches the area infected with jock itch or if you walk around barefoot in a steamy shower room, you will most likely acquire athlete’s foot. The groin area is also prone to heavy sweating, which washes away fungus-killing oils. This encourages the fungus to spread more quickly, just as it would between the toes.