"If you have a stuffy nose, and you take an over-the-counter product containing phenylephrine, you will still not be able to breathe through your nose after you take it. That's the bottom line," contends Leslie Hendeles, a professor of pharmacy and pediatrics at the University of Florida.

He led an extensive data review, published in the July 2006 issue of the Journal of Allergy and Clinical Immunology, that looked at 14 studies focused on the effectiveness of phenylephrine.

Hendeles' conclusion: The products did not relieve nasal congestion.

Based on those findings, Hendeles petitioned the FDA to further investigate the matter, and to boost the maximum allowable dose of phenylephrine in oral decongestants to 25 milligrams, which he believes may be more effective but still safe.

So, on Friday, a joint meeting of the FDA's Nonprescription Drugs Advisory Committee and the Endocrinology and Metabolic Drugs Advisory Committee is listening to testimony on the effectiveness of the current formulation of phenylephrine-containing pills and syrups at relieving nasal congestion.

Hendeles is pushing the FDA to force companies to do studies that compare different doses of phenylephrine to find the most effective one while that is still safe. "There needs to be a dose-response study where you look a 10, 25 and 50 milligram doses and determine what dose would give you a relief of your stuffy nose without side effects," he said.

Oral does of phenylephrine as high as 100 milligrams are effective and safe in easing congestion, Hendeles said.

Phenylephrine is a good drug when administered the right way, Hendeles said. For example, it is an effective decongestant, even at the 10 milligram dose or below, when used in a nasal spray, he said.

"It's just not effective when you swallow it, because enzymes in the gut destroy it, [so] not much drug gets into the blood," he said. "The nasal spray has a fraction of the dose, and it completely opens up your nose."

As reported earlier this month by the Associated Press, the FDA itself also concluded that a 10 milligram dose of phenylephrine is not effective.

According to the agency, seven of 14 studies of 10 milligram doses of phenylephrine, "did not demonstrate a statistically significant effect on nasal airway resistance or symptom scores; in general, the studies are small and lacking many details necessary to provide a convincing demonstration of effectiveness."

Drug companies have recently turned to phenylephrine as a replacement for another decongestant, pseudoephedrine. In 2006, Congress passed a law requiring that products containing pseudoephedrine be kept locked behind the counter and sold in limited quantities. The law was designed to prevent these medications from being bought in bulk and turned into methamphetamine.

Speaking for the effectiveness of the current 10 milligram OTC dose of phenylephrine, the Consumer Healthcare Products Association, an industry group, said that: "This assessment of available scientific evidence concurs with previous findings of the FDA and the OTC expert advisory review panel that oral phenylephrine 10 milligrams is safe and effective as a nasal decongestant for over-the-counter use in adults."

"There are insufficient data in adults to support the assertion that increasing the dose of phenylephrine to 25 milligrams is necessary to produce clinically meaningful improvements in nasal decongestion with a similar safety profile as the currently available 10 mg OTC monograph dose," the group said.

Hendeles believes industry opposition to a dose-response trial is all about money. "They're opposed to anything that costs money," he said. "They have been skimming the profit on all these products that contain phenylephrine. Either they didn't do their homework, or they did this, knowing it's not an effective treatment," he said.

But one expert worried that boosting doses of phenylephrine might come at a price.

"No medicine ever has been shown beyond the shadow of a doubt to be effective for the common cold," noted Dr. Bruce Barrett, an associate professor of family medicine at the University of Wisconsin in Madison. "The main problem with decongestants is that they stimulate the heart and increase blood pressure," he added.

Barrett is concerned that if the dose of phenylephrine is too high, it will result in increased blood pressure and other cardiac problems.

"If applied to tens of thousands of people, you will get cardiac arrhythmias, some of them fatal," Barrett said. "The FDA may need to see studies of tens of thousands of people to see the severity of side effects, and the drug companies may not have the money to do that."

More information

For more about colds and flu, visit the American Lung Association.