America’s most popular cold medications contain a nasal decongestant that doesn’t work, creating a knotty dilemma for regulators, a new study reports.

Cold remedies containing phenylephrine remain consumers’ most popular choice, despite decades of concern that the decongestant simply isn’t effective, researchers say.

The U.S. Food and Drug Administration is considering whether to pull phenylephrine from store shelves, after a key advisory panel voted unanimously in September 2023 that the drug does nothing to clear stuffy noses.

But such a move could create a wave of supply chain disturbances that would leave sick consumers without ready over-the-counter options, researchers report Feb. 8 in the Journal of the American Medical Association.

Phenylephrine tends to be combined with other drugs that are effective — analgesics, cough suppressants and antihistamines — and sold as a multi-symptom product, researchers said. Brands include Dayquil, Sinex, Mucinex and Benadryl.

The only other nasal decongestant approved by the FDA, pseudoephedrine, has become much more tightly regulated because it can be used to make methamphetamine.

Products containing pseudoephedrine can only be purchased by going to a pharmacy counter and handing over a driver’s license, thanks to a 2005 law aimed at combatting illicit meth.

As a result, phenylephrine products have outpaced pseudoephedrine as consumers’ cold remedy of choice, researchers said.

Between 2012 and 2021, consumers bought 19.8 billion units of phenylephrine products, compared to 13.2 billion of pseudoephedrine products.

Even though phenylephrine doesn’t work, the cold remedies that contain it offer other ingredients that do help ease symptoms, researchers noted.

“In contrast to pseudoephedrine, which is often formulated as a standalone product, most phenylephrine products were co-formulated with antihistamines or antitussives [cough suppressants], which are likely to provide some symptom relief for cough and cold symptoms,” wrote the researchers led by Dr. Timothy Anderson, an assistant professor of medicine with the University of Pittsburgh.

If the FDA follows through on plans to pull phenylephrine from store shelves, “reformulation of all phenylephrine-containing products would be required, which could have ramifications for supply chains,” the researchers wrote.

This predicament shows why the FDA needs to more tightly regulate over-the-counter medications, Anderson said.

"The FDA needs to hold over-the-counter drugs to a standard of effectiveness similar to that of prescription drugs,” Anderson said in a university news release. “A comparable pathway is needed for drugs that are sold over the counter as exists for post-approval monitoring of the risks and efficacy of prescription drugs.”