Ringworm is a fungal infection that thrives on the outer layers of the scalp, skin, and nails. This is the same fungus "tinea" that causes “jock itch” and athlete’s foot. Note that ringworm is very contagious. Like athlete’s foot, it spreads from one person to another through things like contaminated gym floors or shower stalls at health clubs, public swimming pools, and other communal type facilities. Contact with an affected animal will also spread the infection.

This condition typically appears as a slightly scaly lesion on the skin. It starts out as a small round, itchy red spot. The infection heals from the inside of the circle to the outer rim, giving rise to the typical ring appearance. It often spreads from one area of the body to another. Ringworm is not a serious infection, but it can be persistent. To confirm a diagnosis, your doctor may gently scratch off some scaly particles from a lesion and examine them under a microscope. The fungus also tends to have a characteristic glow under ultraviolet light. With prompt treatment, ringworm generally clears up in a few weeks. If the fungus is not treated correctly, however, it can lead to a chronic rash or hair loss.