It can waste muscle at high doses for extended periods of time. Also, there can be bloating that goes along with it, but this is user dependent. Lastly, it can increase hunger. If you're only going to be on it for 5 days, stick to your current caloric intake and do not go over it, even if you are hungry. Maybe eat more dense foods. 5 days is not going to kill you and again, the sides are user dependent.
I had to take 150mg for about a week after my heart transplant. With time, that dose when down and down and not I have to take 5mg daily. I was against it at first, but I need to take it for obvious reasons. Like I mentioned, 5 days won't do anything to your body. The one thing it may do is have you retain water, but if you get bloated, that will go away.
I personally saw a little increase in hunger, but ZERO bloating, even at my extremely high doses. If you have any questions PM me, but your doc wants you on it for a reason. Follow his/her orders.