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. Conventional management options are limited to bed rest and treatment of complications such as secondary bacterial infections. 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, a well-known reservoir 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 registry of randomised trials for the Cochrane Complementary Medicine Field was searched using the term "homeopathy" with "influenza", "respiratory tract", "infection", "cough", "virus" and "fever". The manufacturers of Oscillococcinum were contacted for information about other trials. Date of the most recent search: February 1999. SELECTION CRITERIA: Placebo-controlled trials of Oscillococcinum or homeopath-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 ic 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: Oscillococcinum probably reduces the duration of illness in patients presenting with influenza symptoms. 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 homeopathy in influenza and influenza-like syndromes.