Swelling and Pred

Does anyone know whether being on long term Pred can increase swelling from an injury?

I know it can cause probs with bruising more easily so wondered whether swelling (a form of bruising?) could also be more profound.

My son who has been on Pred for over a year now has had 2 knocks recently (one twisted ankle and a swollen elbow from being shoved into a door at school.) Both took ages for the swelling to go down but the amount of pain didn't seem to corrolate with the extent of the swelling.

He is insisting on going the doctors about his elbow as he thinks there is something seriously wrong with it, but is having no probs using it !!