It's been too long for me to tell you the specifics of it but ALWAYS talk to your doctor before taking any supplements. Creatine is very easy to overdose on, which can lead to heart problems down the road. Being that there are no side effects of it you will never know if you are taking too much of it.
I don't know your friend but most people who start body building want to take creatine and whey protein but they don't know how to use it properly. You are what 17/18? All supplements like that do are make up for what you are not getting from your diet, you are young so you should not have that many defincies (depending on your diet). Whey protein is fine (again talk to your doctor first) but Creatine is more advanced than Whey Protein and your friend should be talking to a doctor too. Don't ever put anything into your body unless you know everything it does, side effects, and you have had it okayed by a doctor.

edit: not heart problems I think it's kidney and liver problems. Also, about 99% of the studies done on supplements are done through the companies that make them. So yeah as I've said talk to a doctor and make sure you undrestand everything about it and what side effects to look for etc.