Phenylephrine is the most popular oral decongestant in the country, but further scrutiny by scientists has found that the ingredient is actually no better than a placebo.
Acting on results from at least five studies over the last 20 years – including a 2022 commentary by two University of Florida pharmacists, who plainly stated that oral phenylephrine is ineffective as a decongestant – a Food and Drug Administration (FDA) advisory panel last week unanimously concluded the ingredient doesn’t work in oral form.
Phenylephrine is used in many over-the-counter cold and allergy oral medications, including some DayQuil, Sudafed PE, and Benadryl products. It remains to be seen what action the FDA may take, but possibilities include not allowing oral medications with phenylephrine to be sold, or giving manufacturers a grace period to substitute other ingredients.
According to reports, the oral decongestant industry, which bankrolls a deluge of cold-relief advertisements every fall and winter, generates roughly $1.8 billion in sales annually.
Phenylephrine nasal spray remains effective at relieving congestion, said Sunny Linnebur, PharmD, a professor in the Department of Clinical Pharmacy at the Skaggs School of Pharmacy and Pharmaceutical Sciences.
“One of the problems with the oral phenylephrine is it’s not bioavailable,” Linnebur said. “It’s absorbed and then degraded really quickly, so the concentrations are likely not high enough in the nose to really help provide benefit. But if you used nasal phenylephrine, it gets right to the source.”
In the following Q&A, Linnebur explains how oral phenylephrine got flagged as ineffective and what could happen next. The interview has been edited for brevity and clarity.