Bad Science On Placebos

As Ben Goldacre of The Guardian points out, one of the most interesting thing about placebos is that they work. The effect can also effect the potency of some drugs that should work on a purely chemical level:

[A] study by Daniel Moerman looked at 117 studies of ulcer drugs from 1975 to 1994 and found that the drugs may interact in a way you might not expect: culturally, rather than pharmacodynamically.

Cimetidine was one of the first anti-ulcer drugs on the market, and it is still in use today. In 1975, when it was brand new, it eradicated 80% of ulcers, on average, in various different trials. But as time passed the success rate of cimetidine - this very same drug - deteriorated to just 50%.

This deterioration seems to have occurred particularly after the introduction of ranitidine, a competing and supposedly superior drug.