The risk of serious blood clotting problems depends on the dose of oestrogens. For men, less than the equivalent of three milligrams a day of stilboestrol is probably safe. The safe dose for women is not definitely known but is probably quite a bit higher.
Oestrogens also weaken small blood vessels. You are likely to bruise easily if you take them.
Extra oestrogens cause some special problems for women. You could develop a need to pass urine frequently and/or loss of control of the bladder when coughing, sneezing, laughing etc. If you have not had your uterus removed, you could also experience bleeding from the vagina. This can happen either after you have been taking oestrogens for a long time or when you stop taking them. If the bleeding is heavy, doesn’t stop by itself or happens more than once, you can’t take it for granted that it is simply due to your oestrogen treatment. You should consider having a curette in order to be sure of the reason for such bleeding. A curette involves scraping out the lining of the uterus (womb) through the vagina, under a general anaesthetic if you wish. The lining can then be examined under the microscope to see whether the bleeding was caused just by the oestrogens or by some other problem such as cancer of the lining of the uterus.