the old onion trick., page-9

Why do doctors give it out to clients?

Because they demand "something", often antibiotics specifically.

A GP friend of ours became so fed up with patients' demands for antibiotics when they had the 'flu (which was usually just a bad cold anyway) that she made a loop tape saying that they had a viral infection and that antibiotics wouldn't do any good and would, in fact, just increase the patient's existing but currently benign bugs' resistance to them so that when they WERE needed they'd be useless anyway - or, words to that effect.

Wonder if she's bold enough to tell 'em to go home and sniff an onion ..... :-)