There are some medical conditions where HRT may be too risky. We can’t list all the medical conditions here, but they include uncontrolled high blood pressure, active liver disease, active medical conditions where the risk of blood clotting is very high, after certain (but not all) cancers, where you have abnormal vaginal bleeding that has not been investigated.
The benefits and risks of HRT are different for everybody, and it is important that you talk through your situation with a menopause specialist. It’s also important to discuss your medical history in full before thinking about starting HRT.