One of the conundrums in medical practice is to determine if a medication is causing a side effect. Sometimes, this issue is very straightforward. A new medicine is prescribed. Three days later, the patient develops a new symptom of constipation. The medicine is stopped and the bowel pattern normalizes. Most of us would agree that the evidence that the medicine was responsible for the bowel change is beyond a reasonable doubt.
The above is a textbook example of a side effect, but alas,
patients often have not read the textbook.
Consider a patient having diarrhea from colitis. The gastroenterologist prescribes an
appropriate medication. Two weeks later,
the patient contacts the doctor to report that his diarrhea has worsened. Although diarrhea is among the long list of
potential side effects of the medicine, might the increased diarrhea simply be
from his underlying colitis?
I have seen many examples of patients who come to me with
what seems to be good evidence that a medicine has caused a new and unwelcome
symptom. Yet, when I research the drug,
I do not see this particular side effect listed. (This is hard to believe since it seems that
every drug has a hundred or so side effects listed!) In this case, do I accept that the new symptom
is medication induced or did it arise coincidentally? Do I
reassure the patient that the medicine is not responsible? Do I stop the drug? Should I prescribe a new medicine to attack
the ‘side effect’?
Many of our patients suffer from various chronic diseases
and are on multiple medications. Many of
these folks have ongoing symptoms including nausea, abdominal distress, joint
pains, mood disorders, bowel disturbances, fatigue and headaches. The various symptoms can wax and wane. Who
can tell to the extent that any of these symptoms are caused by one or more of
the medicines? And, if patients are
swallowing a pile of medicines each day, there is a chance that one or two of
them may be interacting with others resulting in side effects.
Determining if a symptom is a side effect often requires the sleuthing skill of Sherlock Holmes. Come Watson, come! He cried. The game is afoot.
Excellent points, Michael. I teach students and residents that if patients are having a symptom and are taking a med (RX or OTC) we should consider an adverse drug reaction in the differential early. Often that is the cause!
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