Placebos...

As part of a project I worked on, we had to document clinical study drugs.

Often these studies included control & test medication.  The control drug is usually a very well documented drug like aspirin or ibuprofen.  Sometimes it's a placebo.  Placebos are not usually accepted as a standard practice for treating medical maladies.

Here's an interesting news article where a VA doctor actually prescribed a placebo: Gulf War Veteran Gets Placebos Instead Of Real Medicine

It's definitely incentive to check the ingredients in your prescriptions.