According to the USDA, it is safe to cook stuffing inside the turkey as long as you pack it loosely and cook the turkey until the stuffing and turkey both reach at least 165 degrees F. It's generally safer to stuff small to medium turkeys and only use about ¾ cup stuffing per pound of turkey weight. Once stuffed, it should be cooked immediately. Never stuff a raw turkey and refrigerate it for any length of time.