Key Ingredient in Popular Cold Medicines Does Nothing, Experts Say

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Woman comparing over-the-counter medicine at the pharmacy
George Rudy /

An ingredient used in over-the-counter decongestant medicines like Benadryl, Dayquil, Sudafed PE and Mucinex does nothing to help with congestion, according to a Food and Drug Administration advisory committee vote this week.

That is true for the dosages currently available on the market, and studying higher doses would “not be safe” due to the ingredient’s effect on blood pressure, the committee’s briefing document says.

The ingredient, phenylephrine, was first evaluated for use in over-the-counter cold medicines in 1976. The new conclusion was based on a review of research studies done since 2007. Some of those studies are more than a decade old.

In other words, the fact that phenylephrine doesn’t work isn’t new information to researchers; the FDA just hadn’t formally reviewed that research until now.

The declaration that phenylephrine is ineffective doesn’t change anything by itself. But the FDA may consider in coming months whether to ban the ingredient, which could cause popular cold and flu products to be pulled from shelves until a new formulation can be produced, The New York Times says.

Changes probably aren’t imminent, though. Any FDA move is likely to be followed by delaying tactics — such as lawsuits and lobbying — from the companies that collectively make at least 250 cold medicines containing phenylephrine, which raked in nearly $1.8 billion in sales in 2022.

In the meantime, there is also no need to throw out cold medicine you have now. Other ingredients in these medicines do help with symptoms, and current formulations are generally safe to continue taking. Not all cold and flu medicines use phenylephrine, either.

That said, people with high blood pressure should be careful with cold remedies generally because of how they work, the Mayo Clinic says:

“Medicines called decongestants cause the most concern for people who have high blood pressure. Decongestants help open a stuffy nose. The medicines narrow blood vessels, which can reduce swelling in the nose area and other parts of the body. But it’s harder for blood to flow through a narrowed blood vessel. This can increase blood pressure.”

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