For a decade of teaching, I still experience this stage fright. I think I am naturally shy but somehow, I overcome them once I get to relax. But I see this kind of fear as natural. It only distracts me when I am among strangers and I must speak before them. I can really feel butterflies and tigers on the loose on my tummy and chest.
I normally have this when I am not at all confident with what I must teach. So, it helps if I am well - equipped with my sources and have prior knowledge about the subject otherwise the fright becomes longer than necessary. Sigh!
Any intervention for severe fright?! Most likely, but I wont resort to them because I would like to overcome my fear the natural way. I can only utter my regular prayers though. LOL!