A little deeper on this
“Pharmacists were telling us, this doesn’t work,” Hatton said.
Approved for use nearly a century ago, phenylephrine is listed as an ingredient in pills, syrups and liquids such as Advil Sinus Congestion & Pain, Flonase Headache & Allergy Relief, and DayQuil Cold & Flu.
But studies over the years have shown that it is not more effective to clear nasal congestion than a placebo when taken orally. Scientists believe that is partly because almost all of it is inactivated in the gut and liver before it reaches the bloodstream.