I had a Mirena for over 4 years - I was post meno. At the time it was the lesser of the Progesterone evils - I had tried other conti HRTs and they all gave me dreadful side effects. I was never offered Utrogestan which I understand is very good. I think the plus of the Mirena is you get little systemic absorption of the progesterone but there is some evidence that a few woman do get side effects. You may be getting an initial spike of progesterone but this may settle down quite quickly. Looking back over my time with the Mirena I think I just suffered occasional bouts of fatigue. If you have been suffering with heavy bleeding whilst going through peri meno or you still need to have contraception because you not post meno, then the Mirena can be a very good option. If you are using Oestrogel or oestrogen patches alongside perhaps this needs to be increased?
Tell us more about yourself - your age and stage of your meno - so we can advice you better.
DG x