Homoeopathic Oscillococcinum for preventing and treating influenza and influenza-like syndromes.

BACKGROUND

Influenza is a highly infectious viral disease that is particularly common in the winter months. Oscillococcinum is a patented, commercially available homoeopathic medicine. The rationale for its use in influenza comes from the homoeopathic principle of 'let like be cured by like'. The medicine is manufactured from wild duck heart and liver, which are said to be reservoirs for influenza viruses.

OBJECTIVES

To determine whether homoeopathic Oscillococcinum or similar medicines are more effective than placebo in the prevention and treatment of influenza and influenza-like syndromes.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) issue 2, 2003; MEDLINE (January 1966 to June 2003) and EMBASE (1980 to June 2003) were searched, using the term "homeopathy" with "influenza", "respiratory tract", "infection", "cough", "virus" and "fever". The manufacturers of Oscillococcinum were contacted for information.

SELECTION CRITERIA

Placebo-controlled trials of Oscillococcinum or homeopathically-prepared influenza virus, influenza vaccine or avian liver in the prevention and treatment of influenza and influenza-like syndromes.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data and assessed methodological quality independently.

MAIN RESULTS

Seven studies were included in the review, three prevention trials (n = 2265) and four treatment trials (n = 1194). Only for two studies was there sufficient information to complete data extraction fully. There was no evidence that homoeopathic treatment can prevent influenza-like syndrome (relative risk 0.64, 95% confidence interval 0.28 to 1.43). Oscillococcinum treatment reduced length of influenza illness by 0.28 days (95% confidence interval 0.50 to 0.06). Oscillococcinum also increased the chance of a patient considering treatment effective (relative risk 1.08; 95% CI 1.17, 1).

REVIEWER'S CONCLUSIONS: Though promising, the data are not strong enough to make a general recommendation to use Oscillococcinum for first-line treatment of influenza and influenza-like syndrome. Further research is warranted but required sample sizes are large. Current evidence does not support a preventative effect of Oscillococcinum-like homeopathic medicines in influenza and influenza-like syndromes.