Ingredient in a lot of cold medications doesn't work, FDA says

September 13, 2023
Four boxes of cold and flu medicine with red and green pills lying loosely in front of them.
A visit to the cold and flu aisle of a Charleston pharmacy showed multiple products containing the decongestant phenylephrine. Photo by Sarah Pack

In a move that was no surprise to allergists but a head-scratcher for a lot of other people, an advisory committee to the Food and Drug Administration said an ingredient found in a lot of oral cold and allergy medications doesn’t work.

Emily Campbell, M.D., an allergist at MUSC Health and assistant professor in the College of Medicine at the Medical University of South Carolina, said it’s called phenylephrine. “They made this decision based on three large clinical trials that failed to demonstrate that this is any better than taking a placebo.”

Phenylephrine has been around for decades. “I think most of us allergists and physicians have been aware that it's not super effective. I think a lot of people also inherently knew that it wasn't effective either when they take it.”

Studies from the 1960s and 70s suggested it did work, but the FDA reviewed them and found they didn’t hold up to modern scientific standards.

You’ll still find phenylephrine listed on the packaging of everything from NyQuil Severe Cold & Flu to Mucinex Sinus Max, Campbell said. “Phenylephrine is supposed to constrict the blood vessels in your nose. And so when you feel really stuffy and congested, it's because you have a lot of increased blood flow to your nose. Theoretically, by constricting the blood vessels in your nose, it helps to open things up.”

Headshot of woman with long reddish blond hair. She is smiling and wearing a white doctor's coat over a dark top. 
Dr. Emily Campbell

And it does, she said – when phenylephrine is the key ingredient in a nasal spray. “But orally, it just doesn't seem to really be as effective in your nasal vessels.”

Campbell said phenylephrine became popular when cold and allergy medications containing pseudoephedrine were moved behind pharmacy counters because pseudoephedrine could be used to make the illegal drug crystal meth. You can still buy them, but you have to ask the pharmacist for them and show an ID.

So a lot of people gravitated to the cold and allergy products that were easier to get.

Campbell said phenylephrine isn’t dangerous. “It just might not be super helpful when you're feeling kind of stuffy and achy and all of those things. It's usually used in combination with other medications like ibuprofen or acetaminophen or sometimes caffeine. And so those other parts of the medication may help you feel better as well. But I probably wouldn't recommend that anybody buy it on its own.”

What she does recommend is pseudoephedrine, which most people know as the key ingredient in the behind-the-counter version of Sudafed. “But one caveat is that it really should be only taken in the short term for a few days when you're having some cold or flu symptoms. And the other caveat is making sure that you check with your doctor before you take it, because it can have some side effects, like increased blood pressure.”

It can also make you feel jittery and cause you to have trouble sleeping. So if you have long term congestion, Campbell said you should see your regular doctor or an allergist. 

She also emphasized that her recommendations apply to adults only. “The American Academy of Pediatrics does not recommend any specific cold or flu medications for nasal congestion for kids. Or cough medicine.”

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