Antibiotics are much more effective at treating a painful urinary tract infection, or, UTIs, than cranberries, according to a new study published in the July issue of Archives of Internal Medicine.

Researchers did a double-blinded study of 221 premenopausal women with recurrent UTIs over a year.

Dr. Marielle A.J. Beerepoot, from the Academic Medical Center in Amsterdam, and her colleagues randomly chose 110 women and treated them with a daily dose of an antibiotic, trimethoprim-sulfamethoxazole, or TMP-SMX, while the other 111 were given cranberry capsules twice a day for the year.

Researchers found that the women who took the cranberry capsules reported having twice as many UTIs than those who took antibiotics. The women who took the antibiotics had their first infection after eight months. However, the women who took cranberry capsules saw their first infection in four months, according to the report.

Though the antibiotic was more effective than the capsules, researchers said the body tended to build its resistance against the antibiotics, and therefore, it may not respond to the drugs while treating another infection.

"In terms of ability to prevent recurrent infections, the antibiotic was about twice as effective as cranberry, but it results in more antibiotic resistance,"  Dr. Lianne Marks, an internal medicine physician at Scott & White Healthcare, in Round Rock, Texas, told CNN. Marks wasn't involved in the study.

The research showed that after a month, 86.3 percent of the, Escherichia coli, or E coli,samples from the women treated with antibiotics were showing resistance to the medications, when compared to the 23.7 percent of women treated with the cranberry capsules. Additionally, cranberry supplements have a lower risk of side-effects and are less likely to develop antibiotic resistant strains of bacteria.

The authors concluded that in premenopausal women, the once daily 480 milligrams of TMP-SMX, is more effective than twice-daily 500 milligrams cranberry capsules to prevent UTIs. But this is "at the expense of emerging antibiotic resistance," according to the study.