Crinone is a vaginal gel, rather than a capsule like Utrogestan, or an external gel like Oestrogel.
As for dosage, I think only 8% is available in the UK now. I understand here was a choice of 4% previously (and maybe still in States) and that the studies were done with that.
You also asked about side effects. Nothing that I notice particularly apart from a few spots sometimes just before the next crinone. But as that does not make me feel bad, it is just a minor irritation compared to Utrogestan which was unbearable.
I originally started taking it in the morning and it left me feeling tired and fed up but switched to taking at night and that disappeared.
