Estriol is a type of estrogen made by the ovaries and is used in bioidentical hormone replacement therapy (BHRT) in the form of a vaginal cream for postmenopausal women to reduce unwanted symptoms of vaginal dryness, hot flashes and other effects of menopause. The development of a “natural” estrogen such as estriol was to avoid some of the unwanted side effects created by synthetic estrogen. Some of these side effects include breast soreness as well as “a higher risk of breast cancer, heart disease, stroke and blood clots,” according to Harvard Medical School.
Women who used estriol cream, according to a study reported by the National Institutes of Health, experienced some initial burning and heat-generation feelings at their vagina. These were felt during the first few days of treatment and went away thereafter.
The Menopause Journal Web site reported on a small study using estriol cream by suppository application that showed positive effects from estriol use as far as vaginal dryness and balanced pH of the vagina. The 19 healthy postmenopausal women who were part of the study had no endometrial hyperplasia problems after 6 months.
According to Harvard Medical School, there is no evidence that bioidentical hormone treatments like estriol cream are any safer than synthetic hormone treatments. Assertions that estriol creams produce fewer cases of or increased risk of endometrial cancer remain unproven.