I have been prescribed prednisone 3 months ago as well as a form of isotretinoin for my skin condition. Just wondering if the prednisone will affect any muscle mass I have as I will most likely be taking the drug for 1-3 more months (3-6 total). I was first at 80 mg and the dosage drops every ten day by 10 mg. I am currently taking 20 mg but this ammount may increase depending on if my skin has a reaction to the isotretinoin.