In this radio discussion, Lars Larson and I discuss the efficacy of over-the-counter cold and allergy medications, specifically those containing phenylephrine. The radio host expresses his concern as someone who relies on his voice for his profession, and who occasionally uses these medications to alleviate congestion.
I discussed the main ingredient in many of these medications, phenylephrine, a medication that has been around for a quarter of a century but whose approval as an effective therapeutic is equally as old and not the current state of the art. Modern tests and trials indicate that it is not effective.
Lars specifically mentioned using DayQuil, which contains phenylephrine, and feeling relief within 15 minutes. I suggest that this could be attributed to psychosomatic or placebo effects, which are well known. I explained the phenomena of the placebo effect and what might be thought of as its mirror image, the nocebo effect, where individuals may experience adverse reactions to inert substances simply because they believe they should.
Lars asked what people should do if these medications, even if placebos, are taken off the market. I suggested that such a move might not come for some time, primarily because of regulatory inertia and the large volume of these medications sold. (I support their removal from the market, given the real side effects, e.g.,, nausea or rapid heart rate, that are associated with phenylephrine.) Individuals might consider alternative medications containing pseudoephedrine, which has proven effectiveness but is kept behind the counter due to its illicit use for the production of methamphetamine.
We ended by explaining and discussing the post hoc, ergo propter hoc (after the fact, therefore because of the fact) fallacy, where individuals attribute their recovery to a treatment simply because improvement occurs after the administration of the treatment -- but without proof that treatment and improvement were actually cause and effect.
You can find the entire audio interview with Lars Larson here.
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Or this piece by my colleague Dr. Josh Bloom