trapped with fungi in the warm, dark, moist inside of a shoe. Fungal infection of the nails is called tinea unguium, and is not included in the medical definition of "athlete's foot", even though toe nails are part of the foot. Fungi are more difficult to kill inside and underneath a nail than on and in the skin. But if the nail infection is not cured, then the fungi can readily spread back to the rest of the foot. The fungi can also spread to hair, grow inside hair strands, and feed on the keratin within hair, including the hair on the feet, the hair of one's beard, and the hair on one's head. From hair, the fungi can spread back to skin. To effectively treat athlete's foot, it is necessary to treat the entire infection, wherever it is on the body, until the fungi are dead and the skin has fully healed. There is a wide array of over the counter and prescription topical medications in the form of liquids, sprays, powders, ointments, and creams for killing fungi that have infected the feet or the body in general. For persistent conditions, oral medications are available by prescription. Tinea unguium (nails) Onychomycosis (also known as "dermatophytic onychomycosis," or "tinea unguium" is a fungal infection of the nail. It is the most common disease of the nails and constitutes about half of all nail abnormalities. This condition may affect toenails or fingernails, but toenail infections are particularly common. It occurs in about 10% of the adult population. Tinea manuum (hand) Tinea manuum (or tinea manus) is a fungal infection of the hand. It is typically more aggressive than tinea pedis but similar in look. Itching, burning, cracking, and scaling are observable and may be transmitted sexually or otherwise, whether or not symptoms are present. Tinea cruris (groin) Tinea cruris, also known as "crotch itch", "crotch rot", "Dhobie itch", "eczema marginatum", "gym itch", "jock itch", "jock rot", "scrot rot" and "ringworm of the groin" is a dermatophyte fungal infection of the groin region in any sex, though more often seen in males. In the German sprachraum this condition is called tinea inguinalis (from Latin inguen = groin) whereas tinea cruris is used for a dermatophytosis of the lower leg (Latin crus). Tinea cruris is similar to Candidal intertrigo, which is an infection of the skin by Candida albicans. It is more specifically