My son is fifteen years old and his feet stink badly. How can he completely deodorize?

The default reason for your son's smelly feet is that he sweats a lot, so,

Wash your feet frequently, you can't change them once a day. If you can, please ask once at noon and once before going to bed at night. Please wash your feet with soap when you wash your face. Please wash your toenails and change socks every day, keep your feet ventilated and dry, and please use antibacterial and antiperspirant foot massage spray according to the instructions, at least once a day. Wear ventilated shoes to keep them free of odor. Before use, sprinkle antiperspirant powder or spray on the feet inside the shoes, or in the worst case, sprinkle some talcum powder. When shoes are not worn, put them in a cool and dry place and put some mothballs. If the above situation is maintained for more than 1 month, the symptoms will be obviously improved, otherwise, please see a doctor. Keep a good habit of cleanliness, otherwise beriberi will recur. Please don't pinch your feet often, otherwise it will infect your hands or even your face.