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Tuesday, August 14, 2012

The nocebo

You’re familiar with the placebo effect, but have you ever heard of the ‘nocebo’ effect? Just as the illusion of treatment can make people feel better, the suggestion of negative effects can make people feel worse. For example, reading about the possible side effects of a treatment can make people believe they suffer from those ailments. Remember, as with the placebo, the negative effects are not caused by any real treatment. In fact, patients receiving placebos in clinical trials will have negative nocebo effects if the tested medicine is perceived to have those effects.

This means that participants will sometimes drop out of clinical trials due to adverse reactions, even when they were actually in the placebo branch of that study. People also report less satisfaction with pharmacologically identical generic drugs than with name brand preparations.

This puts doctors in a precarious position. Ethically, they are required to make sure their patients are informed about the possible risks and side effects of treatments. However, just mentioning possible problems makes it more likely that their patients will suffer from them. Contrary to common assumption, forewarning a patient that a procedure will ‘sting’ or ‘burn’ often increases the perceived pain. Again, this is true even if the treatment was a sham and the patient never actually got the treatment.

Winfried Häuser of the Technische Universität München and his colleagues have a few suggestions for how doctors can navigate the treacherous waters between giving too little and too much information. Physicians can emphasize the rarity of side effects, or they can ask patients to willingly forego learning about unlikely and/or minor side effects. Personally, I think the latter choice would turn me into a hypochondriac on the spot. Of course, phrasing matters. What would you choose if your doctor asked you the following? 
A relatively small proportion of patients who take Drug X experience various side effects that they find bothersome but are not life threatening or severely impairing. Based on research, we know that patients who are told about these sorts of side effects are more likely to experience them than those who are not told. Do you want me to inform you about these side effects or not?

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