Can vaginal oestrogen therapy do more than simply relieve symptoms -- such as preventing urinary tract infections or even extending your life?

Vaginal oestrogen substantially reduces recurrent urinary tract infections: on average 58% fewer infections compared with placebo, as shown by a meta-analysis of five randomised trials. A large cohort study involving more than 5,600 women confirmed this: in the year following the prescription, women had more than half as many infections. That is a concrete and clinically meaningful difference.

The mechanism of action is reasonably well understood. Oestrogen significantly lowers the pH of the vagina. That more acidic environment is unfavourable for the bacteria that cause urinary tract infections. This explains why local administration specifically works: oral oestrogen pills leave the vaginal environment unchanged and do not reduce infections, as the same meta-analysis showed.

Beyond urinary tract infections, vaginal oestrogen also helps with bladder symptoms: sudden urinary urgency, urinating too frequently, and getting up at night to use the toilet all decreased substantially in studies. Stress incontinence -- the involuntary loss of urine when coughing or sneezing -- also improved. Here the evidence often comes from before-and-after comparisons without a control group, so the quality of evidence is somewhat weaker than for infection prevention.

Not everyone benefits equally. Women aged 75 and older, and women with diabetes, bladder retention, or incontinence, continued to experience infections more often despite treatment. The therapy apparently only partly addresses the underlying problem in these individuals.

There are no data on life extension. None of the available studies examined this. You are therefore right to ask, but it remains unanswered at this time. Regarding safety: most vaginal preparations do not raise blood oestrogen levels above the postmenopausal norm, and abnormalities of the uterine lining are very rare. Local irritation or a burning sensation are sometimes reported, but in randomised research this did not occur statistically more often than with placebo.