Neem extract have been fount to be effective against tinea pedia, the fungus that causes athletes foot. Fungal infections of this type affect nine out of ten people in the United States at some time or another. Untreated, this fungus can attack the toenails and even cause secondary infections throughout the body. A corn starch powder combined with powdered neem leaves makes an excellent preventative while alcoholic neem leaf extract or neem-based lotion can be used if an infection has already begun.