Still waiting for evidence about whether cranberries are a useful treatment for urinary tract infections

Cranberries contain a substance that can prevent bacteria from sticking on the walls of the bladder. This may help reduce bladder and other urinary tract infections (UTIs). Cranberries (usually as cranberry juice) have been used to try and treat UTIs, particularly in high risk groups such as older people. Cranberries have few adverse effects. The review found no evidence from studies about the effects of cranberry juice or other cranberry products on UTIs.

Authors' conclusions: 

After a thorough search, no RCTs which assessed the effectiveness of cranberry juice for the treatment of UTIs were found. Therefore, at the present time, there is no good quality evidence to suggest that it is effective for the treatment of UTIs. Well-designed parallel group, double blind studies comparing cranberry juice and other cranberry products versus placebo to assess the effectiveness of cranberry juice in treating UTIs are needed. Outcomes should include reduction in symptoms, sterilisation of the urine, side effects and adherence to therapy. Dosage (amount and concentration) and duration of therapy should also be assessed. Consumers and clinicians will welcome the evidence from these studies.

Read the full abstract...

Cranberries (particularly in the form of cranberry juice) have been used widely for several decades for the prevention and treatment of urinary tract infections (UTIs). The aim of this review is to assess the effectiveness of cranberries in treating such infections.


To assess the effectiveness of cranberries for the treatment of UTIs.

Search strategy: 

The search strategy developed by the Cochrane Renal Group was used. Also, companies involved with the promotion and distribution of cranberry preparations were contacted; electronic databases and the Internet were searched using English and non English language terms; reference lists of review articles and relevant studies were also searched.
Date of last search: July 2010

Selection criteria: 

All randomised controlled trials (RCTs) or quasi-RCTs of cranberry juice or cranberry products for the treatment of UTIs. Studies of men, women or children were included.

Data collection and analysis: 

Titles and abstracts of studies that were potentially relevant to the review were screened by one author, RJ, who discarded studies that were clearly ineligible but aimed to be overly inclusive rather than risk losing relevant studies. Authors RJ and LM independently assessed whether the studies met the inclusion criteria. Further information was sought from the authors where papers contained insufficient information to make a decision about eligibility.

Main results: 

No studies were found which fulfilled all of the inclusion criteria. Two studies were excluded because they did not have any relevant outcomes and two studies are currently being undertaken.