In a peer-reviewed letter to the editor published recently in the Journal of Allergy and Clinical Immunology, two University of Florida researchers concluded that there is “virtually no evidence to show that phenylephrine oral nasal decongestants at the FDA-sanctioned dose of 10mg are effective.”
U.S. Congressman Henry Waxman (D.-Ca) has twice called upon the US Food and Drug Administration (FDA) to launch an investigation into the use of phenylephrine in these drugs. The latest call came after release of a new study by Schering-Plough:
According to the drug firm, phenylephrine was "not significantly different from placebo in decreasing nasal congestion" while pseudoephedrine was "significantly more effective," in a clinical trial involving 38 people.
“Medical studies indicate that phenylephrine may be no more effective than placebo in alleviating nasal congestion, raising questions regarding FDA's conclusion that the drug is safe and effective for over-the-counter use,” said a statement on Waxman's website.
Despite Waxman's calls, the FDA has so far declined to undertake a review. Source.