How to stop a dog from chewing on himself?

desitin works well. It seems to help my dog that has very bad allergies and scracthes himself raw. My aunt also uses it for her dog that chews on his feet. Her vet told her to use it to help them stop biting and chewing, it seems to help keep the itching down and I don't think they like the smell or taste so they don't chew at the spots until it is all gone.