Does echinacea really work? Scientists already know that echinacea is effective in reducing the severity and duration of upper-respiratory-tract infections. However, less is known about the herb’s ability to reduce symptoms of the common cold.

Researchers studied 128 men and women within 24 hours of their having exhibited common cold symptoms, such as sneezing, nasal discharge, nasal congestion, headache, sore or scratchy throat, hoarseness, muscle aches and coughing. Participants were given either a placebo or 100 milligrams (mg) of echinacea three times a day until the symptoms disappeared or until the end of a 2-week period. At the close of the study, no differences were found in the severity or duration of symptoms experienced by either group.

Writing in the Archives of Internal Medicine (2004; 164 [11], 1237–41), the researchers stated, “Some studies have concluded that echinacea effectively reduces the symptoms and duration of the common cold. We were unable to replicate such findings. Further studies . . . are necessary to validate previous claims.”