Australasian Science: Australia's authority on science since 1938

Are All Placebos Equal?

By Peter Bowditch

Is the placebo effect the same whether you receive it as a pill, a needle or an ointment?

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I’ve written twice this year (January and September) about psychological effects that can influence a person’s perception of pain or other stimuli. This month I’m looking at some research into the difference between various placebos used in trials of methods to treat the same complaint.

Watching television I see two advertisements that seem to appear on multiple occasions each night. Both are for over-the-counter treatments for osteoarthritis pain in the knees. In one of them a grey-haired gentleman with a short grey beard takes pills containing paracetamol to relieve the pain, enabling him to play with his (grand)children by swimming or running with a kite. The other advertisement shows a woman, apparently much younger than the man in the pill ads, who eases the pain by rubbing her knee with ointment out of a tube.

Research published in The Annals of Internal Medicine ( has examined different placebos used in clinical trials of treatments for knee pain caused by osteoarthritis. There are four basic forms of treatment – topical gels and creams, intra-articular injection, oral medication and oral plus topical. Obviously, any placebo treatment must match the real treatment being evaluated, but what researchers were interested in was whether the different forms of placebo had effects that were different enough to possibly distort the findings...

The full text of this article can be purchased from Informit.