Probiotic (Friendly Bacteria) Lactobacillus Does Not Prevent Vaginal Yeast Infections After Antibiotic Treatment In Women

Research published in the August 27, 2004 British Medical Journal found that lactobacillus taken either orally or vaginally does not — as it has long been believed to — prevent vaginal yeast infections in women being treated with antibiotics. Lactobacillus has even been referred to as a probiotic, meaning “friendly bacteria.” Vaginal yeast infections are usually caused by the organism Candidia albicans.

The study was conducted in Australia and involved 278 women between the ages of 18 and 50 with non-gynecological infections who started short-term oral antibiotic treatment within 48 hours of their participation in the study. The results from 235 of these women were available for analysis. The study used the scientific “gold standard” randomized placebo controlled design. Women were randomly assigned to receive either oral or vaginal lactobacillus-containing products or corresponding placebos. The medications and placebos were used during, and continued for four days after, antibiotic treatment was stopped.

The trial was terminated early after an interim analysis found that the lactobacillus preparations were ineffective.

Overall, 55 of the 235 women (23%) developed a vaginal yeast infection. In women given the oral lactobacillus preparation there was no statistical difference in the number of vaginal yeast infections in women using lactobacillus compared to women getting the placebo. The same statistical result of no difference was found for the vaginal preparation and the placebo.

The authors of the study commented that there is no feasible explanation as to how oral lactobacillus could survive stomach acid and antibiotics and then sucessfully grow in the lower bowel and vagina. Also, lactobacillus-containing vaginal preparations are killed by antibiotics. The authors commented further “Unless a biologically plausible theory develops, further research in this subject is unlikely to be fruitful.”

Their final conclusion:

The use of lactobacillus in post-antibiotic vulvovaginitis is an example of a treatment that has widespread use despite lack of a biologically plausible basis or evidence of effectiveness. Our results should prompt health professionals to inform women that lactobacillus is unlikely to prevent post-antibiotic vulvovaginitis and that they should consider using proved antifungal treatment if symptoms develop.

No matter how strongly we believe that a treatment may work, believing does not make it so. Some of our most cherished, long-held therapeutic beliefs about widely used and accepted treatments, when subjected to rigorous scientific research, often are found to fail. Lactobacillus to prevent vaginal yeast infections is yet another example.

The failure of common therapeutic “knowledge” when examined rigorously is not limited to complementary and alternative medicine or dietary supplements such as lactobacillus. It also applies to Food and Drug Administration (FDA) prescription drugs when they are used “off-label” for uses for which they are not approved.

Two recent examples involve FDA-regulated drugs and long-held beliefs about therapeutic value that did not pan out when the studies were done. The first is the belief that antidepressants are safe and effective in children and adolescents (see Worst Pills, Best Pills News December 2003). The second is that hormone replacement therapy protects women from heart disease, prevents Alzheimer’s disease and improves quality of life (see Worst Pills, Best Pills News September 2002 and March 2004).

What You Can Do

If you develop a vaginal yeast infection after antibiotic treatment, use a product that is FDA-approved to treat the infection.