One of my first medical publications was on the nocebo effect, the unpleasant symptoms patients may suffer as a result of being made aware of potential side effects of a treatment they are about to receive or a procedure they are to undergo. Thus patients who were having a lumbar puncture were either told or not told they might suffer a headache afterwards; and lo and behold, those who were told that they might get headaches duly got headaches while those who were not told didn’t.

On the whole, as an article in a recent edition of the Journal of the American Medical Association points out, doctors are well aware of the placebo effect, that is to say the good that their treatment may do patients by means of mere suggestion, but have little awareness of the opposite nocebo effect, the harm that their treatment may do their patients by mere suggestion.

The nocebo effect poses an ethical dilemma for doctors, say authors of the article. On the one hand, doctors are supposed to do their patients no harm; on the other, they are supposed to be open and honest with their patients about the potential harms of drugs and other treatments. The dilemma is this: foreknowledge of those harms can harm some patients. Should the need for honesty trump the ethical injunction to do no harm?