Can you transfer an iphone 5 sim card to an iphone 5s?

My friend really needs an iphone 5 and they no longer sell them, so he said that he would buy me a 5s and let me keep my sim card if I gave my 5 to him. Will I have any problems if I just take my old iphone 5 sim card out and put it into a new 5s? Please respond as soon as possible.

Not at all!

No. IPhone 5s use nano sim while iPhone 5 use micro sim.
A sim card is only $10 though. Not that big of a deal