How long is it safe to take corticosteroids?

[cheechchong_pt2 0]

I just finished accutane, like 3 weeks ago and I have some problems with my throat (not because of accutane) and I might have to take prednisone for a week or 2. I remember 3 years ago I took it for like 3 weeks and I developed chest acne, and gained 10lbs. I'm really scared this may happen, so how long is it safe to take it not to gain weight or most importantly not to get acne? I read that the onset is usually 2-6 after the drug is initiated but I'm very concerned.