Australian scientists say they have found no evidence that probiotics can relieve the irritating symptoms of eczema and what is more they suggest they may sometimes cause infections and gut problems.
Probiotics are live micro-organisms taken by mouth such as the Lactobacillus bacteria found in unpasteurised milk and yoghurt.
The researchers led by Dr. Robert John Boyle of the Royal Children's Hospital in Parkville, Victoria, reached this conclusion following a review of the best available research on the topic.
Eczema is a red and itchy skin rash that affects up to 20% of children and research has found that the guts of people with eczema have a different bacterial environment than those without the condition and sometimes they have inflammation in their gut.
This led to the idea that it may be possible to treat eczema symptoms by changing the mix of gut bacteria or by reducing inflammation in the gut and administering probiotics or "good" bacteria could help treat the disease.
Though some doctors recommend probiotics for eczema, the treatment is a controversial one and there is evidence that it can lead to harmful side effects.
In order to further investigate the issue Boyle and his colleagues reviewed 12 randomized controlled trials comparing probiotics to a placebo in 781 children with eczema.
The review of twelve trials found that probiotics do not reduce eczema symptoms such as itching, nor do they change the overall severity of eczema according to patients or their doctors.
The researchers say the quality of the studies was mixed, and overall the suggestion was that probiotics were not effective as no significant reduction in disease severity or improvements in quality of life were seen.
Though the results varied between different trials, probiotics were not found to be an effective treatment for eczema and the researchers say there is not enough evidence to recommend using probiotics for the treatment of eczema.
They say while no study showed reductions in absenteeism from school or work any beneficial effect of the treatments studied is likely to be modest.
Many studies it seems did not provide information on side effects, but among the minority that did give this information, the researchers found no significant difference between the groups given probiotics and those given placebo.
The researchers say while probiotic treatment is generally safe, it can lead to adverse events including sepsis and bowel ischaemia, which is likely to be very low for most people.
Dr Boyle says further studies of new probiotics are needed, because it is possible that different types of probiotics which haven't yet been studied in eczema treatment could be more effective.
The review is published in the Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research.