To the apparent consternation of many Americans, an FDA advisory panel has unanimously concluded that oral phenylephrine (PE), a common decongestant found in brands such as Sudafed PE, Vicks Sinex, Tylenol Sinus, and Benadryl Allergy Plus Congestion (but not Benadryl on its own, as some news outlets have erroneously reported), is ineffective.
Like pseudoephedrine, phenylephrine is an alpha-1 agonist that in theory, if not in practice, constricts blood vessels in the nose and relieves swelling and congestion. The FDA advisory panel cited the <1% bioavailability of PE as a reason for its lack of efficacy. This paves the way for the FDA to remove these PE-containing medications from store shelves should they decide to do so.
However, the FDA has raised concerns about “potential unintended consequences” from such an action and signaled caution. Many patients swear by these brands, so their removal would leave a void, (even if the much more bioavailable pseudoephedrine, a meth precursor, is available behind pharmacy counters) and subject the FDA to the possibility of public backlash.
The fact that, on average, most symptoms, especially common cold ones, tend to get better on their own over time, with or without intervention is almost irrelevant; many patients with cold-or-flu-like symptoms may come away convinced that these over the counter (OTC) medications, which they took, made them feel better, even if chicken soup would have worked just as well.