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Homeopathy for prevention and treatment of flu

Clinical bottom line:

There is no evidence that homeopathic preparations for the prevention or treatment of flu are more effective than placebo. The few high quality trials showed no benefit of homeopathy over placebo. There were significantly more adverse events in the homeopathy group compared with the placebo group in one of the prevention trials suggesting that these remedies should be taken with caution in light of the lack of real benefit.

Oscillococcinum is a commercially available homeopathic remedy prepared from wild duck heart and liver, a reservoir for influenza viruses. This remedy conforms to the homeopathic principle of 'let like be cured by like'. Despite its biological implausibility, Oscillococcinum is a very popular homeopathic remedy.

Systematic review:

Vickers AJ, Smith C. Homeopathic Oscillococcinum for preventing and treating influenza and influenza-like syndromes (Cochrane Review). In: The Cochrane Library, Issue 1, 2000.Oxford: Update Software.

Date review completed: February 1999

Number of trials included: seven randomised controlled trials

Number of patients: 3459 patients in active and control groups

Control groups: placebo

Main outcomes: Influenza symptoms (temperature, cough, chills, pain, sore throat, rhinitis), duration, global assessment of improvement, medication use.

Inclusion criteria were randomised placebo controlled trials; homeopathic Oscillococcinum of any dose or other homeopathic remedies prepared for influenza prevention or treatment; any outcome measure of influenza severity or duration except laboratory tests.

Reviewers conducted a search of the Cochrane database and contacted manufacturers of Oscillococcinum for unpublished data. All trials were scored for methodological quality, A, B or C, on a number of different criteria. Quality score A indicates a low risk of bias and C a high risk of bias. Reviewers converted ordinal to dichotomous data in order to pool data for quantitative analysis. Trials where homeopathy was given to prevent flu symptoms were analysed separately from trials where homeopathy was given to treat flu symptoms. Reviewers presented results as relative risks.

Overall trials were of low to moderate quality. The validity of pooling trials for meta-analysis is questionable since treatment regimes, patients and trial methodology were different. Overall, reviewers suggest that homeopathy was significantly better than placebo for some outcomes. When the higher quality studies are considered separately from the lower quality, biased studies, significant benefit of homeopathy is only shown in the lower quality studies for a few outcomes among many negative outcomes.



There were four treatment trials reporting on 1194 patients. Two trials were of high methodological quality (A for each criterion); there were no significant differences between homeopathy and placebo for the primary outcomes. The other two trials were of lower methodological quality and reported some significant findings amongst many negative outcomes. Relative risk estimates were all non-significant.


There were three prevention trials reporting on 2265 patients, children and adults. There was no difference between treatment and placebo groups in any of the studies for any outcome. Relative risk estimate for occurrence of influenza-like syndrome was 0.64 (95% confidence intervals: 0.28 to 1.4).

Whilst the reviewers report that there may be some benefit of Oscillococcinum for the treatment of flu symptoms on some outcomes, the RCTs of the highest quality showed no difference.

Adverse effects

Reviewers reported that there were no serious adverse effects in the treatment trials. In one of the prevention trials 77/783 patients on homeopathy versus 17/790 on placebo reported mild adverse effects e.g. headache. The relative risk for the occurrence of an adverse effect was 4.6 (2.7 to 7.7) and number needed to harm was 13 (10 to 19).



Again, a homeopathy review that demonstrates no evidence of any effecicacy, but some p[ossibility of minor harm.

Further reading

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