Cranberry extract prevented recurring urinary tract infections (UTI) as effectively as standard antibiotics and with fewer side effects. Researchers explained that bacteria learn to resist antibiotics and wanted to find preventive non-drug alternatives that don’t increase bacterial resistance.
About 140 women aged 45 or older with recurring UTI took 500 mg of cranberry extract or 100 mg of the antibiotic trimethoprim per day for six months. Both groups had a new infection after about 90 days, but 78 percent more women on trimethoprim dropped out due to side effects such as itch or rash, compared to the cranberry group
Journal of Antimicrobial Chemotherapy; 2009, Vol. 63, No. 2, 389-95.