Hi Sfifties - I wan't advised by a specialist, I think I read it on here. I had to use progesterone as I was using a high dose of oestrogen (75 patch or 3 pumps oestrogel), and I really struggled with progesterone of any kind, it made me really ill, black moods, excessive brain fog, rage, extreme water retention, bloating and various digestive issues, insomnia, night sweats and hellish dreams whenever I did sleep, but I had to find a way to use progesterone, so I reduced my oestrogen to 2 pumps or 50 patch and tried the alt day method. I can't really remember how I felt on it as I started having spotting (coincidental) and was investigated, a polyp was found and I had to have it removed. The polyp was probably due to high oestrogen and not enough progesterone for quite a few years, I don't know this for sure, but the biopsy said it was oestrogen fed. Please don't let this put you off, I was using high oestrogen and very limited prog for a number of years.
The 100mg utro dose is much higher progesterone than we would naturally produce during a natural cycle (20-40mg, except in pregnancy), and I just couldn't tolerate that level, it made me insane. Whether it's utrogestan or a synthetic progestin, the dose is high in hrt to ensure the womb lining is either properly shed or impaired from growing under the influence of oestrogen.
You're right that it's not licensed, however, many women have used/tried it and dependent on where you are in your meno, you may find it works for you, you won't know unless you try it. The problem, as with all standard hrt is that women are not standard! But we're given 'standard' doses, presumably reached through controlled clinical studies, but not nuanced to incorporate the incredibly complex way each of us metabolise these products.
In effect your taking a 50mg dose, daily vaginally of utro which for some women, will offer enough protection. There are some clinical studies to prove that it is effective, I'll see if I can find them and you can show them to your GP.