Is it okay for a 15 year old to smoke an e-cig and are there any side effects of using one of them??

Where? Laws vary by area. In the US, these laws are on a state by state basis. I know CO has set the minimum at 18. The FDA last year proposed similar rules on a nationwide basis.

They aren't safe like they are claimed to be.

Nicotine is even more addictive than Heroin... There are still compounds in the ecigs you do NOT want in your body if you want to live a long and healthy life.

In short, NO.

No, it is not healthy, it is a ugly habit and one that is not needed.