Hi Stripes
I've been on tibolone for two months and I am having a very positive experience and no side effects.
I don't have endometriosis but I do have three small but very reactive fibroids that bled a lot when I started taking conventional HRT. I experienced the whole 2ww pathway shebang with scan, hysteroscopy and biopsy, like so many other women on the forum.
The consultant suggested I try tibolone, rather than having surgery on the fibroids. I was initially quite dubious of a synthetic steroid as I had been adamant I wanted body-identical (and preferably transdermal) HRT, but I'm really glad I tried it. I find it very gentle but effective - no bleeding at all, and no breast pain and bloat (which I'd also experienced on 50 Evorel and Utrogestan).
The only thing about tibolone is that it's possibly quite weak - I'm guessing equivalent to 50mcg patch or less or 1-2 pumps of gel - so might not be enough if you need higher doses of oestrogen. I'm 56 and four years post meno, but do still have my ovaries. I wonder if they are doing something in the background as my meno symptoms weren't that bad compared to some (mainly frequent headaches, low mood, loss of libido, dryness and VA, joint pain) - all are vastly improved on tibolone.
So I wanted to reassure you that tibolone is definitely worth trying, even though it's synthetic, and I have been very, very pleasantly surprised by how good I feel on it.