Background: Chinese herbal medicines are frequently used to treat the common cold in China. Until now, their efficacy has not been systematically reviewed.
Objectives: To assess the effectiveness and safety of Chinese herbal medicines for the common cold.
Search strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 3, 2006) which contains the Acute Respiratory Infections Group's specialised register; MEDLINE (1966 to July 2006); EMBASE (1980 to March 2006); AMED (1985 to July 2006); and the Chinese Biomedical Database (CBM) (1975 to July 2005).
Selection criteria: Randomised controlled trials (RCTs) studying the efficacy of Chinese herbal medicine(s) for the treatment of the common cold were included, irrespective of publication status or language.
Data collection and analysis: Four review authors telephoned original trial authors of the RCTs identified by our searches to verify the randomisation procedure. Two review authors extracted and analysed data from the trials which met the inclusion criteria.
Main results: Fourteen studies involving 2440 patients were included. The methods of all studies were rated of poor quality (category C). Included studies used "effective drugs" as controls; however, the efficacy of these control drugs was not reported. Different Chinese herbal preparations were tested in nearly all trials; in only one was a Chinese herbal preparation tested twice. In six studies, five herbal preparations were found to be more effective at enhancing recovery than the control; and in the other eight studies, five herbal preparations were shown to be equal to the control. There was a strong probability of different biases in all of the included studies.
Authors' conclusions: Chinese herbal medicines may shorten the symptomatic phase in patients with the common cold. However, the lack of high quality clinical trials means we are unable to recommend any kind of Chinese herbal preparation for the common cold.