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'Nocebo
Effect' May Explain Some Drug Side Effects
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By Merritt McKinney NEW
YORK (Reuters Health) -
A phenomenon called the "nocebo
effect" may explain why some people report side
effects that are not related to the medications
they are taking, according to a new report.
Most people have heard of
the placebo effect, in which people on an inactive
drug or therapy experience improvement in their
symptoms. Researchers compare new drugs to placebo
to gauge the true benefit of a therapy.
The placebo effect can make
people feel better, but sometimes a dummy pill can
have the opposite effect. Believing that they are
taking an active medication, some patients develop
side effects when taking a placebo.
This phenomenon is dubbed
nocebo, which means "I will harm" in Latin. Placebo
means "I will please" in Latin.
This nocebo effect may help
explain why people taking real medications sometimes
experience side effects that do not seem to be caused
by the drug, according to Dr. Arthur J. Barsky and
colleagues at Brigham and Women's Hospital in Boston,
Massachusetts.
These so-called nonspecific
side effects can have serious consequences, the
researchers note in the February 6th issue of The
Journal of the American Medical Association. Such
side effects may cause patients to stop taking medications
or physicians to discontinue effective drugs. In
a review of medical studies, Barsky's team identified
several factors that seem to be related to the nocebo
effect and nonspecific side effects of active medications.
The power of positive thinking
may account for some of the placebo effect, but
negative thinking has a power of its own, according
to the researchers.
"Patients who expect distressing
side effects before taking a medication are more
likely to develop them," they state. The power of
suggestion can be influential as well. In one clinical
trial the authors reviewed, patients who had been
warned of the possibility of gastrointestinal side
effects of a medication were much more likely to
experience such symptoms than those had not been
told of the possible side effects.
Nonspecific side effects
may be more common in people who have experienced
side effects while taking medication in the past,
the report indicates. Barsky and his colleagues
also assert that patients with certain characteristics,
such as anxiety and depression, may be more likely
to experience nonspecific side effects.
What a person knows about
a particular medication and even the color, name
or shape of a pill may influence nonspecific side
effects, the investigators note. One study found
that more than 90% of people who had been classified
as allergic to penicillin were able to take oral
penicillin. It is possible, according to the authors,
that some patients who were fearful of having a
bad reaction to penicillin misinterpreted symptoms
that were not caused by the drug.
In another study, patients
taking blue placebo pills were more likely to report
drowsiness than patients taking pink ones. The researchers
point out that in one study, patients associated
red, orange and yellow pills with stimulants and
blue and green ones with sedatives.
In an interview with Reuters
Health, Barsky said that there is little people
can do to stop having symptoms. But it is useful
for people to realize that "most of the time we
have symptoms" of one type or another.
Most people feel drowsy,
have a patch of dry skin or forget a phone number
from time to time, but these symptoms may seem a
much bigger deal during an illness, Barsky said.
When you get sick, "you begin
to pay more attention to your body," he said. "You
pick up on these things you would previously ignore"
and attribute them to medications.
Before automatically blaming
a symptom on a medication, Barsky advised people
to think about whether they have had this symptom
before and how often it occurred before jumping
to the conclusion that it is a side effect of a
drug.
SOURCE: The Journal of the
American Medical Association 2002;287:622-627.
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