PredniSONE Side Effects: For those of you asking how long it takes for the moon face to go http://www.medications.com/effect/view/37576 For those of you asking how long it takes for the moon face to go away... it was about a month for me after I tapered down to 5 mg. I can never go off of it completely b/c of organ transplants, but don't really have side effects when I'm on 5 mg. Even when how long have you been taking the medication to get moon face? I Wed, 31 Dec 2008 06:51:15 -0500 http://www.medications.com/effect/view/37576?item=15615 how long have you been taking the medication to get moon face? I start my package tomorrow for a week. I got the shot today and have been up all night. http://www.medications.com/effect/view/37576?item=15615