Relative risk of vaginal candidiasis after use of antibiotics compared with antidepressants in women - Postmarketing surveillance data in England

Background: Vaginal candidiasis is a common infection in women. The microflora of the vagina are influenced by a number of factors, including pregnancy, oral contraceptive use, menses and diabetes mellitus. Previous antibiotic use is generally accepted to be a risk factor for vaginal candidiasis but the published evidence to support this is limited. Aim: To determine the relative risk of vaginal candidiasis following the use of antibiotics compared with antidepressants in prescription-event monitoring (PEM) studies. Methods: Using data from postmarketing surveillance studies of six antibiotics and six antidepressants, conducted using the observational cohort technique of PEM, the number of reports of vaginal candidiasis was determined in women aged greater than or equal to16 years, in, each of the first 7 weeks following a prescription for one of these drugs. The relative risks for vaginal candidiasis following the use of these antibiotics and for each of the individual antibiotics compared with antidepressants were calculated for each week and for the overall 7-week period. Women treated with antidepressants were the most suitable comparator group from the PEM database, as they were of a similar age range and the studies were conducted at a similar time period to those of the antibiotics. Also, there was no pharmacological plausibility for vaginal candidiasis being associated with antidepressants. Results: There were 188 reports of vaginal candidiasis in 31588 women, aged greater than or equal to16 years, treated with antibiotics and 70 in the 45492 treated with antidepressants. The relative risk for vaginal candidiasis (antibiotic/antidepressants), was highest in the second week, 10.70 (95% CI 4.86-23.55) but was also significantly greater in the first and third weeks after the start of treatment. The risk was also higher in each of the 3 weeks after starting the course for five of the antibiotics, compared individually to the group treated with antidepressants, the exception being fosfomycin, which had a much smaller cohort. Conclusion: This study shows a significant increase in the risk of developing vaginal candidiasis following the use of the antibiotics studied (ciprofloxacin, ofloxacin, norfloxacin, cefixime, azithromycin and fosfomycin) compared with that after taking the antidepressants fluvoxamine, fluoxetine, paroxetine, sertraline, venlafaxine and nefazodine in these PEM studies.