Theoretically there should be fewer side effects with utrogestan when taken vaginally because it doesn't have to be digested nor go through the liver nor be churning round the blood stream with all its metabolic by-products. The French Product info leaflet gives vaginal use as an alternative to oral use when side effects such as excessive tiredness, nausea, dizziness etc are experienced. However I have also read papers showing that the systemic levels are actually higher when the same dose is used vaginally - for the same reason ( ie less lost to digestion).
I am generally pretty tired quite a lot of the time these days anyway especially in the mornings so hard to say - I usually get progressively more tired in the mornings and foggy headed towards the end of my course but I am taking 200 mg so I am on a long cycle. I have never taken it orally nor taken 100 mg for any length of time.
I couldn't take the utro in the mornings - I've had 4 children and it would fall straight out. If you haven't had children then maybe would be OK but I would still prefer gravity not to be acting on it so it would ooze up cervix to uterus more easily ( stands to reason really). As for intimacy - probably best to insert (Utro) afterwards - so it's a question of knowing when it's going to happen! Not so easy......even so I would worry a bit about dilution but so far it hasn't been a problem for me - for a variety of reasons I won't go into

Hurdity x