Chinese medicinal herbs for influenza

Influenza is an acute respiratory communicable disease which can cause high morbidity and mortality in an epidemic. Traditional Chinese medicinal herbs following a particular theory may be a potential medicine of choice.

The objective of this review was to assess the therapeutic effect and adverse reaction of Traditional Chinese medicinal herbs in treating uncomplicated influenza.

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2004); MEDLINE (January 1966 to October 2004); EMBASE (January 1988 to October 2004); CBM (Chinese Biomedical Database) (January 1980 to December 2003); and the Chinese Cochrane Center's Controlled Trials Register (up to December 2003). We also searched Current Controlled Trials (www.controlled-trials.com) and the National Research Register (http://www.update-software.com/National/) for ongoing trials and reference lists of articles. We wrote to researchers in the field, or authors of studies evaluated in the review for more information.

Randomised and quasi-randomised trials comparing traditional Chinese medicinal herbs with placebo, or various other Chinese medicinal herbs, or with other current regimes normally used in care or comparing drugs with herbal preparations to simple drugs in treating defined uncomplicated influenza patients.

At least two reviewers extracted data and assessed trial quality.

Eleven studies with the number of participants ranged from 52 to 479. In total 2,088 participants were included in the review. As the interventions of the included studies were different from each other and most of the studies were of low quality, we did not perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data were acquired in the included studies. Eleven studies with the number of participants ranged from 52 to 479, 2,088 in total were included. As the interventions of the included studies were different from each other and most of the studies were of low quality, we failed to perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data was acquired in the included studies.

The small number of included studies and participants, as well as the low quality of most studies, made the evidence far from conclusive for clinical decision making, although traditional Chinese medicinal herbs as a whole seem to be comparatively or more effective compared to different chemical drugs. A certain herbal preparation could not be recommended for there was not enough evidence. More high quality randomised controlled trials (RCTs) with similar interventions are required to strengthen the evidence for the efficacy and safety of certain herbal preparation.