Review: Cranberry and urinary tract infections

Dr. David Guay from the University of Minnesota, in Minneapolis has reviewed the evidence.

Is it good for treating urinary tract infections?

  • There’s no evidence that cranberry can be used as treatment.

Can cranberry treatment prevent urinary tract infections?

  • Effectiveness is variable.
  • Recurrence of infection over 1 year is reduced approximately 35% in young to middle-aged women.
  • Efficacy is questionable in the elderly, pediatric patients, those with neurogenic bladder, and those with chronic indwelling urinary catheters.
  • Problems exist with standardization of cranberry products, making it difficult to compare products or extrapolate results to other cranberry products.
  • No study has evaluated the specific active cranberry-derived compounds (anthocyanidin/proanthocyanidin).

How does it work?

  • Distinct flavonoids found in cranberry, known as proanthocyanidins, irreversibly inhibit certain bacteria from adhering to urinary tract cells and causing infection.

Is it difficult to keep taking it long-term?

  • Up to 55% of patients stop taking cranberry treatment, suggesting it may not be acceptable over long periods.

What are the side effects of treatment?

  • Gastrointestinal intolerance
  • Weight gain (due to the excessive calorie load)
  • Drug-cranberry interactions due to its effect on cytochrome P450 metabolizing enzymes

The bottom line?
Dr. Guay concludes, “In light of the heterogeneity of clinical study designs and the lack of consensus regarding the dosage regimen and formulation to use, cranberry products cannot be recommended for the prophylaxis of recurrent UTIs at this time.”

Others have reviewed the evidence and agree.

However, a Cochrane review concluded, there’s some evidence that cranberry juice may decrease the number of symptomatic urinary tract infections, particularly in women with recurrent infections.

5/16/09 20:14 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.