trimethoprim/sulfamethoxazole. Some recommend against prolonged use due to concerns of antibiotic resistance. Methenamine is another agent used for this purpose as in the bladder where the acidity is low it produces formaldehyde to which resistance does not develop. A UK study showed that methenamine is as effective daily low-dose antibiotics at preventing UTIs among women who experience recurrent UTIs. As methenamine is an antiseptic, it may avoid the issue of antibiotic resistance. In cases where infections are related to intercourse, taking antibiotics afterwards may be useful. In post-menopausal women, topical vaginal estrogen has been found to reduce recurrence. As opposed to topical creams, the use of vaginal estrogen from pessaries has not been as useful as low dose antibiotics. Antibiotics following short term urinary catheterization decreases the subsequent risk of a bladder infection. A number of vaccines are in development as of 2018. Children The evidence that preventive antibiotics decrease urinary tract infections in children is poor. However recurrent UTIs are a rare cause of further kidney problems if there are no underlying abnormalities of the kidneys, resulting in less than a third of a percent (0.33%) of chronic kidney disease in adults. Whether routine circumcision prevents UTIs has not been well studied as of 2011. Alternative medicine Some research suggests that cranberry (juice or capsules) may decrease the number of UTIs in those with frequent infections. A Cochrane review concluded that the benefit, if it exists, is small; so did a randomized controlled trial in 2016. Long-term tolerance is also an issue with gastrointestinal upset occurring in more than 30%. Cranberry juice is thus not currently recommended for this indication. As of 2015, probiotics require further study to determine if they are beneficial. The role of the urinary microbiome in maintaining urinary tract health is not well understood as of 2015. , one review found that taking mannose was as effective as antibiotics to prevent UTIs, while another review found that clinical trial quality was too low to allow any conclusion about using D‐mannose to prevent or treat UTIs. Treatment The mainstay of treatment is antibiotics. Phenazopyridine is occasionally prescribed during the first few days in addition to antibiotics to help with the burning and urgency sometimes felt during a bladder infection. However, it is not routinely recommended due to safety concerns with its use, specifically an elevated risk of methemoglobinemia (higher than normal level of methemoglobin in the