Researchers Find Modest Placebo Effects in Treatment of the Common Cold

Investigating placebo effects in treatment of the common cold, Bruce Barrett, MD, PhD, of the University of Wisconsin, Madison, and colleagues, report finding modest and nuanced effects related to receiving pills regardless of their content, especially among those who believe in a particular therapy. The four-armed trial (no pill, placebo, Echinacea blinded and Echinacea unblinded), which included 719 randomized participants aged 12 to 80 years, revealed that patients randomized to the no-pill group had longer and more severe illnesses than those who received pills, regardless of the pills content.

Specifically, those randomly assigned pills reported colds that were on average 0.16 to 0.69 days shorter and 8 to 17 percent less severe than those who didnt receive pills. Among those who believed in the efficacy of Echinacea and received pills, illnesses were substantively shorter and less severe, regardless of whether the pills contained the Echinacea. Specifically, those who received pills and rated Echinaceas effect highly had illnesses that were 1.31 to 2.58 days shorter and 26 to 29 percent less severe. The authors conclude these findings, which suggest small but meaningful effects related to expectation and pill allocation, support the idea that patients beliefs and feelings about treatments should be taken into consideration when making medical decisions.

Reference: Barrett B, et al. Placebo Effects and the Common Cold: A Randomized Controlled Trial. Annals of Family Medicine. July/August 2011.