IPhone 5s heats up

Hi guys,

I got another problem,I think apple can't live without giving list of issues to their customer.

However, my iPhone 5s gets hot when I use it for few minutes likes just I make video call

On skype for only two minutes yes just it gets hot and that is

not comfortable.by the way I am using it with out any casing.I have purchased it

just month ago.

Please help me.

Thanks n regards