Efficacy and safety of oral phenylephrine: systematic review and meta-analysis

Oral phenylephrine is used as a decongestant, yet there has been no previously published systematic review supporting its efficacy and safety.

To assess the efficacy and safety of oral phenylephrine as a nonprescription decongestant.

MEDLINE, the Cochrane Central Registry of Controlled Trials, EMBASE, International Pharmaceutical Abstracts, and the Federal Register were searched for English and non-English-language studies published through January 2007 that measured the effects of oral phenylephrine on nasal airway resistance (NAR) in patients with nasal congestion. The retrieved studies were supplemented with information from our personal files and by hand searches of the references in any of the studies. Additionally, a Web of Science Search was conducted using the Cited Reference function for all published clinical trials identified. Studies included in the analysis were randomized, placebo-controlled trials; studies of combination products were excluded. Two investigators independently extracted data on NAR, self-reported decongestant effects, and cardiovascular effects (ie, heart rate, blood pressure) from each of the included studies. Meta-analyses were performed for NAR and cardiovascular effects using a random effects model. Subjective decongestant effects were summarized.

Based on 8 unpublished studies that included 138 patients, phenylephrine 10 mg did not affect NAR more than placebo; the mean maximal difference in relative change from baseline between phenylephrine and placebo was 10.1% (95% CI -3.8% to 23.9%). Eight unpublished studies on phenylephrine 25 mg showed a significant reduction of maximal NAR compared with placebo of 27.6% (95% CI 17.5% to 37.7%). There was significant heterogeneity among the studies included in this analysis, which was partially attributable to different laboratories and methods used. Patient-reported decongestion was not consistently better for any phenylephrine dose compared with placebo, and NAR was a more sensitive measurement of efficacy. Phenylephrine showed no consistent effect on heart rate or blood pressure for doses of 25 mg or less.

There is insufficient evidence that oral phenylephrine is effective for nonprescription use as a decongestant. The Food and Drug Administration should require additional studies to show the safety and efficacy of phenylephrine.