Cranberries May Not Prevent UTIs, and May Aggravate Some Bladder Pain

Cranberries contain a substance that can prevent bacteria from sticking on the walls of the bladder, which may help prevent bladder and other urinary tract infections. UTI’s are about 50% more common in women then men, due to the shorter female urethra allowing bacteria easier access to the bladder. A recently published review is the third update to assess the effectiveness of cranberry products in preventing urinary tract infections (UTIs) in susceptible people. The authors looked at all randomised controlled trials (RCTs) or quasi-RCTs of cranberry products for the prevention of UTIs as cranberries (usually cranberry juice) have been used to prevent UTIs.

This review ‘identified 24 studies (4473 participants) comparing cranberry products with control or alternative treatments. There was a small trend towards fewer UTIs in people taking cranberry product compared to placebo or no treatment but this was not a significant finding. Many people in the studies stopped drinking the juice, suggesting it may not be an acceptable intervention. Prior to the current update it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period, particularly for women with recurrent UTIs.

The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. Although some of small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included. Cranberry products were not significantly different to antibiotics for preventing UTIs in three small studies. Given the large number of dropouts/withdrawals from studies (mainly attributed to the acceptability of consuming cranberry products particularly juice, over long periods), and the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs. Other preparations (such as powders) need to be quantified using standardised methods to ensure the potency, and contain enough of the 'active' ingredient, before being evaluated in clinical studies or recommended for use’.1

When cranberry products aggravate bladder pain, this often identifies painful bladder syndrome or interstitial cystitis (IC), a chronic inflammation of the bladder lining. Symptoms can include: urinary frequency, urgency, bladder discomfort, painful intercourse and pelvic pain.

For IC sufferers cranberry acts like an ‘acid bomb’ causing a painful flare up.

This site lists suitable and problematic foods for IC sufferers.

View the Interstitial Cystitis cookbook

This clinical trial uses honey as an innovative new treatment for IC, painful bladder and chronic pelvic pain syndromes.


1.  Cranberries for preventing urinary tract infections. Ruth Jepson, Gabrielle Williams, Jonathan Craig.Pub Online: 17 OCT 2012 DOI: 10.1002/14651858.CD001321.pub5