In the UK it is obligatory to provide any medication, with a written list of side-effects and contra-indications. With all the antibiotics I have ever been prescribed, there is a notice advising taking some form af acidophilus (be it in the form of a yoghurt or proprietary liquid) for a week after the antibiotics prescription is finished.
So in the UK, this is standard procedure. And most times, the Doctor will mention it too....