Don't Ignore the Placebo Effect

In the mid-1990s, echinacea became the new, faddish, herbal concoction of choice to deal with the common cold. It turns out to be completely ineffective, according to this report [registration required, though it is probably in the archive by now]:

The study, ... published ... in The New England Journal of Medicine, involved 437 people who volunteered to have cold viruses dripped into their noses. Some swallowed echinacea for a week beforehand, others a placebo. Still others took echinacea or a placebo at the time they were infected.

Then the subjects were secluded in hotel rooms for five days while scientists examined them for symptoms and took nasal washings to look for the virus and for an immune system protein, interleukin-8. Some had hypothesized that interleukin-8 was stimulated by echinacea, enabling the herb to stop colds.

But the investigators found that those who took echinacea fared no differently from those who took a placebo: they were just as likely to catch a cold, their symptoms were just as severe, they had just as much virus in their nasal secretions, and they made no more interleukin-8.

I wonder how effective a placebo is, compared with doing nothing.

Several years ago, I was with my friend, BenS, in a drug store when he asked, "Where do you keep your placebos?"