Why don't we we get a skin infection back on our fingers when we apply creams on them, like on ringworms,etc?

when you have an infectious skin problem that spreads or grows bigger (like a ringworm), you treat them with creams using your fingers or hands, shouldn't they get the infection too?

Why don't we we get a skin infection back on our fingers when we apply creams on them, like on ringworms,etc?
because the medicine on your fingers are your protection
Reply:You should wash your hands thoroughly after applying the cream, or else you can either get the infection on your hands or spread it somewhere else.