MARSHFIELD, Wis.--Echinacea has been shown to have little effect on the symptoms and duration of the common cold, according to a new study published in the June issue of The Archives of Internal Medicine (164, 11:1237-41, 2004) (http://archinte.ama-assn.org).

In the randomized, double blind, placebo-controlled study, duration of symptoms was observed amongst 128 patients with upper respiratory infections receiving either 100 mg of freeze-dried Echinacea purpurea from the aerial portion of the plant, or a lactose placebo three times daily for 14 days or until cold symptoms desisted. The patients were matched for sex, age, time from onset of symptoms to enrollment in the study, average number of colds per year, and smoking history. Symptoms, including sneezing, nasal discharge and congestion, headache, sore or scratchy throat, hoarseness, muscle aches and cough, were scored subjectively by patients and recorded daily in diaries. The authors of the study found no statistically significant differences between groups for total symptom scores, mean individual symptom scores, or time to symptom resolution, were unable to validate earlier research indicating that echinacea effectively reduces the symptoms and duration of the common cold, and recommended further studies involving different preparations and dosages of echinacea to validate previous claims.