Homeopathic Oscillococcinum® for preventing and treating influenza and influenza-like illness

Review question
To determine whether homeopathic Oscillococcinum® is more effective than placebo in the prevention and/or treatment of influenza and influenza-like illness in adults or children.

Background
Influenza ('the flu') is a highly infectious viral respiratory disease. Other than treatments for complications (such as pneumonia), the conventional medical strategies for the prevention or treatment of flu are not entirely effective or satisfactory. Oscillococcinum® is a highly diluted homeopathic preparation manufactured from wild duck heart and liver, which may be reservoirs of flu viruses. Some people take Oscillococcinum® regularly over the winter months either to prevent flu or as a treatment for flu symptoms.

Study characteristics
We included six studies, which comprised two prevention trials (a total of 327 young to middle-aged adults in Russia) and four treatment trials (a total of 1196 teenagers and adults in France and Germany).

Key results
The findings from the two prevention trials did not show that Oscillococcinum® can prevent the onset of flu. Although the results from the four other clinical trials suggested that Oscillococcinum® relieved flu symptoms at 48 hours, this might be due to bias in the trial methods. One patient reported headache after taking Oscillococcinum®. The evidence is current to September 2014.

Quality of the evidence
The overall standard of research reporting was poor, and thus many aspects of the trials' methods and results were at unclear risk of bias. We therefore judged the evidence overall as low quality, preventing clear conclusions from being made about Oscillococcinum® in the prevention or treatment of flu and flu-like illness.

Authors' conclusions: 

There is insufficient good evidence to enable robust conclusions to be made about Oscillococcinum® in the prevention or treatment of influenza and influenza-like illness. Our findings do not rule out the possibility that Oscillococcinum® could have a clinically useful treatment effect but, given the low quality of the eligible studies, the evidence is not compelling. There was no evidence of clinically important harms due to Oscillococcinum®.

Read the full abstract...
Background: 

Influenza is a highly infectious viral disease that is particularly common in the winter months. Oscillococcinum® is a patented homeopathic medicine that is made from a 1% solution of wild duck heart and liver extract, which is then serially diluted 200 times with water and alcohol.

Objectives: 

To determine whether homeopathic Oscillococcinum® is more effective than placebo in the prevention and/or treatment of influenza and influenza-like illness in adults or children.

Search strategy: 

We searched CENTRAL (2014, Issue 8), MEDLINE (1966 to August week 4, 2014), MEDLINE In-Process & Other Non-Indexed Citations (4 September 2014), AMED (2006 to September 2014), Web of Science (1985 to September 2014), LILACS (1985 to September 2014) and EMBASE (1980 to September 2014). We contacted the manufacturers of Oscillococcinum® for information on further trials.

Selection criteria: 

Randomised, placebo-controlled trials of Oscillococcinum® in the prevention and/or treatment of influenza and influenza-like illness in adults or children.

Data collection and analysis: 

Three review authors independently extracted data and assessed risk of bias in the eligible trials.

Main results: 

No new trials were included in this 2014 update. We included six studies: two prophylaxis trials (327 young to middle-aged adults in Russia) and four treatment trials (1196 teenagers and adults in France and Germany). The overall standard of trial reporting was poor and hence many important methodological aspects of the trials had unclear risk of bias. There was no statistically significant difference between the effects of Oscillococcinum® and placebo in the prevention of influenza-like illness: risk ratio (RR) 0.48, 95% confidence interval (CI) 0.17 to 1.34, P value = 0.16. Two treatment trials (judged as 'low quality') reported sufficient information to allow full data extraction: 48 hours after commencing treatment, there was an absolute risk reduction of 7.7% in the frequency of symptom relief with Oscillococcinum® compared with that of placebo (risk difference (RD) 0.077, 95% CI 0.03 to 0.12); the RR was 1.86 (95% CI 1.27 to 2.73; P value = 0.001). A significant but lesser effect was observed at three days (RR 1.27, 95% CI 1.03 to 1.56; P value = 0.03), and no significant difference between the groups was noted at four days (RR 1.11, 95% CI 0.98 to 1.27; P value = 0.10) or at five days (RR 1.06, 95% CI 0.96 to 1.16; P value = 0.25). One of the six studies reported one patient who suffered an adverse effect (headache) from taking Oscillococcinum®.

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