The key ingredient that underpins many nasal decongestants don't work as promised when taken orally.

Following an evaluation of clinical trial data, a panel of expert advisors for the United States Food and Drug Administration (FDA) agrees oral phenylephrine-based (PE) drugs are no better at reducing stuffiness than a placebo. While still safe to ingest, too much of the medicine is broken down before it gets to the bloodstream to have any real effect, they say.

The panel's recommendation, laid out in a briefing document published this week, is that the FDA reclassify oral PE decongestants so that they are not falsely labeled as effective.

This could force manufacturers to reformulate products like Advil Sinus Congestion & Pain, Sudafed PE Nasal Decongestant, and Tylenol Cold & Flu Severe, among many, many others.

As expected, many of these manufacturers are not happy. A trade organization representing the companies, called the Consumer Healthcare Products Association, said in a statement reported by CNBC it was "disappointed" by the panel's vote and urged the FDA to tread carefully.

At the same time, many scientists have welcomed the panel's conclusions. In fact, since 2006, researchers at the University of Florida have been petitioning the government to review the effectiveness of oral PE as a nasal decongestant.

Finally, their concerns are being heard.

The FDA advisory panel highlights at least three large, controlled clinical trials that have tested orally administered PE in recent years and found that it is not effective at any dose.

They describe the data as "consistent, substantial, and believable".

How the FDA will respond to the panel's vote remains to be seen. Because PE-based decongestants are still deemed safe for human consumption and can treat other symptoms of colds and allergies, they might be allowed to stay on the shelves.

If manufacturers are forced to pull their products from the market, it could lead to a momentary collapse in the availability of cold, allergy, and flu medications, as manufacturers reformulate their drugs.

Nevertheless, the advisory panel warns that if these products remain on the market, consumers will continue to spend millions on medicines that contain possibly ineffective ingredients.

The authors note oral decongestants containing PE were estimated to have brought in 1.76 billion dollars in sales in the US in 2022. And that doesn't even count business from Costco, convenience stores, specialty stores, internet sales, phone sales, or kiosks.

By comparison, other decongestant alternatives to PE, like pseudoephedrine (PSE), which actually do help reduce stuffiness, brought in 542 million dollars in sales in 2022.

PSE drugs, however, are often only available behind the counter or within locked cabinets, which means that many consumers aren't aware they are an option.

To make matters even trickier to navigate, liquid eye drops and nasal sprays, which deliver PE more directly to the bloodstream, are still considered effective decongestants.

"Consumers will require education to make the appropriate choices for alternative treatments," the advisory panel acknowledges.

The briefing document can be found here.