A placebo is a dummy treatment, a tablet, injection or some other formulation that contains no medicine. It can be a sugar pill masquerading as a painkiller, a moisturizing cream pretending to cure wrinkles or a wristband designed to improve balance. They share one thing in common - they should be useless. But they aren't. A placebo can often relieve pain and improve mood, they are able to treat arthritis and insomnia, offer relief from anxiety and depression, and sometimes even improve fertility.
No-one knows exactly why they sometimes work as well as real ones. It probably has something to do with what we want to believe: sham treatments work best when we pay a lot of money for them or consult an 'expert' to receive it. Interestingly, the type of tablet can make a difference: big, colourful pills always work better than small, plain ones. But there's more: yellow pills are best for treating depression, blue pills are good for insomnia and white tablets ease indigestion. Placebo injections are better than empty capsules for pain and a big 'healing' machine that goes 'ping!' works better than the lot.
There must be more than simple self-belief. Seeing a doctor or therapist is healing in its own right. That relationship and decision to take action can lower anxiety levels and reduce stress hormones. But they should never be used as a replacement for prescribed medicines.
Placebos only seem to be effective in about 4 out of 10 people - and we can't tell in advance who those will be. Finally, the placebo effect can also work even when people are told they are placebos. For example, when doctors prescribed sugar pills for patients with irritable bowel syndrome, fully explaining that they weren't real medicines and giving out the pills in a jar labelled 'placebo' - most patients had significant relief from their symptoms.
Dr Stuart Farrimond, Wiltshire Times 13 June 2014
