As Catlady711 said, call your vet and keep him/her on alert and find out what to watch for. Years ago, my late Peke-a-poo, Charmin, ate a nylon footie and, fortunately, she passed it. My vet told me that, if I see her passing it, DO NOT try to help her by pulling on it because it could injure her internally. So, if you should see the hair band making its way out, watch until she passes it and see if there's any blood and/or pain involved w/it and, by no means, help her. If it appears that she's in real pain when passing it and/or if there's blood, call your vet immediately. Please let us know what happens. And gather up anything that she can get ahold of and put it somewhere safe where she can't get it.