Propecia or finasteride does not affect your transplanted hairs. It may have sexual side effects for 1 to 2% of the men.
Finasteri has hormonal sıde effects but ıf you stop takıng it the side effects will go away as well. It mıght lower your sex drıve.
Finasteride after a hair transplant will prevent hair loss from the native hair that is still there after the transplant