When you stroll down the cold and flu aisle in a drugstore, it's easy to get lost in the dizzying array of products promising to clear sinus pressure, dry up sniffles and stop plaguing coughs. Some concoctions even offer it all in one magical pill.

But doctors say the science behind some of those claims is lackluster.

"There's just not much that's very effective for treating the common cold," said Dr. Lauren Eggert, clinical assistant professor in the Pulmonary Allergy and Critical Care Division at Stanford University.

"Most of the things out there — antihistamines, decongestants, cough medicines — none of them have a lot of evidence that they're super effective at improving cough or common cold symptoms."

Headlines blasted that message in September when advisers to the FDA found oral phenylephrine, which is an active ingredient in some Sudafed, Mucinex, and Dayquil products, is simply not effective. The review was prompted by inquiries dating back nearly a decade.

And pharmacists say that concerns over effectiveness could extend down the aisle. Half a dozen medical experts interviewed for this story raised questions about other cold and flu ingredients, including other common cough suppressants and expectorants.

"There could well be products that are on the market containing ingredients about which people could legitimately have questions and which the agency has had a difficult time acting on because of the elaborateness of the regulatory process," said Dr. Peter Lurie, the president of the Center for Science in the Public Interest, a consumer watchdog group.

Many of the ingredients on store shelves today were grandfathered in more than 50 years ago, when the science backing many drugs did not meet the rigor of today's methodologies. This means companies have been able to create new products using those ingredients without testing their effectiveness.

"Back in those days, statistics were not very developed," said Dr. Leslie Hendeles, PharmD, professor emeritus at the University of Florida in Gainesville, who was one of the petitioners who prompted the recent FDA review. "The whole concept of clinical trials and study design was in its infancy."

But most of these drugs have remained on store shelves unquestioned, thanks to the FDA's laborious drug review process. Reforms included in the 2020 CARES Act streamline requirements. Prior to these reforms, updating or changing a drug's approval status required FDA notice-and-comment rulemaking, which is slow and burdensome. Now a much simpler administrative order is required.

The law also provides the FDA with the authority to collect user fees from drug manufacturers. The new funds are intended to provide the agency with adequate staffing to implement new drug reviews and removals.

For example, pharmacists like Hendeles submitted a citizen's petition to the FDA to review oral phenylephrine back in 2007. This year's vote is the new law's first test case. In the future it should not take 16 years for a drug review to unfold.

"The message here is that there are a lot of products on the market that fall into the same category as phenylephrine," said Hendeles. "They're not for diseases where people die or have to go to an emergency room. So they have not gotten the attention — even from the FDA — until now."

He believes regulators will likely find other futile over-the-counter drugs as they review older medications. "I know for sure that the cough suppressants and the expectorants are next in line."

He points to a compilation of data he presented in a 2018 paper published in the journal Allergy and Asthma Proceedings, where he concluded the claims on many OTC products marketed for respiratory symptoms are overblown. And the existing evidence for decongestants, expectorants and cough suppressants does not "justify their use."

Eggert agrees. She opens a database called UpToDate, which physicians use as a resource when they want to see the summary of evidence for medications targeting specific concerns. The conclusions for cold and flu remedies are disconcerting:

• Antihistamines, vitamins and herbal remedies are deemed ineffective.
• Cough syrups, decongestants, expectorants, and zinc may have minimal or uncertain benefits.
• Nasal sprays and analgesics like Tylenol and ibuprofen may be effective.

NPR reached out to the FDA to clarify whether the agency is planning to review some of these drugs. The agency did not provide comment or make anyone available for an interview after numerous requests.

Industry groups like the Consumer Healthcare Product Association are pushing the agency to keep oral phenylephrine available to drugstores, even though CVS stores have already started pulling oral decongestants containing phenylephrine as the only active ingredient.

In an email, they defended the FDA's current review process saying it ensures that cold and flu medications are safe and effective. Additionally, in a statement, they argue that "decreased choice and availability of these products would be placed directly onto consumers and an already-strained U.S. healthcare system."

For now, Eggert recommends consumers use products with the best evidence like acetaminophen (Tylenol) for pain or nasal sprays to clear the nose.

And, she does not suggest tossing anything else out of your medicine cabinet.

"If you've used something and you felt like it was helpful, I don't think there's a problem with that," said Eggert. "There's little harm for people who are looking for relief. And I do believe in the placebo effect."

But it may be best to avoid concoctions that promise to treat many symptoms at once. Single-ingredient products will help lower the possibility for side effects, according to Dr. Shalini Lynch, PharmD, health sciences clinical professor at UCSF's School of Pharmacy. She says it should be obvious in a day or two if the product is relieving a desired symptom.

She also suggests a few natural remedies. Saline nasal rinses may help clear your sinuses and honey can quell your cough. Additionally, it may be worth standing in a steamy shower or filling your humidifier to open your nasal passages.

However, Lynch says cozying up on the couch may be your best bet.

"The common cold is something that pretty much needs to run its course," she said. "You want to feel better instantly. But the reality is most cough and cold, viral types of upper respiratory infections, just take time to go away."