A placebo is a treatment with no active , such as a sugar pill. Surprisingly, patients who placebos often report that they better. This is as the placebo effect. It is for symptoms that the brain helps to , such as pain and . Because of this effect, new medicines are against placebos to show that they work than alone.

The word placebo comes from Latin and means ‘I shall please’. For centuries, doctors gave harmless pills or tonics to patients for whom they had no real cure, hoping that the treatment would at least comfort them.

In the twentieth century, placebos became a scientific tool. In a randomized controlled trial, patients are assigned by chance to receive either a new treatment or a placebo. In a double-blind design, neither the patients nor the researchers know who receives which. This method prevents expectations from distorting the results.

Researchers have also found that the setting of treatment matters. In some studies, larger pills, more expensive-looking packages, and a warm, attentive doctor all increased the improvements that patients reported.

Perhaps most surprising are open-label placebo studies. In a 2010 study at Harvard, patients with a long-term stomach condition were told plainly that they were taking sugar pills. Many still reported clear improvement compared with patients who received no pills at all. Scientists are still debating why. One possibility is that the ritual of taking medicine triggers the body’s own responses to care.