How long does it take for the water retention to go away from taking predisone?

At the peak of my treatment I was on 60mg a day and I gained weight, water bloating and a big moonface, not to mention the lump on the back of my neck and hairs growing in new places (bad). Once I tapered down to under 10mg a day I started to see all the side effects ease and my moonface was gone by the time I was at 5mg. The podgy water filled middle I had also eased away but it took a little longer. Everyone is different but one thing that seems to be common is that once you get onto low doses or off the drugs then you will start to see the bloasting etc ease.

Have you stopped the Prednisone? Fluid retention is a short term side effect and should disappear soon after treatment has stopped. Talk with your doctor if the fluid retention is not diminishing or you are concerned.