I would not suggest that a 15 yr old use diet pills of any kind. If by chance they would help you lose some weight (most of the time they don't work), you will only gain it back once you stop taking them.
It would be much better is you incorporate a sensible diet and exercise into your routine to lose weight, so you will be able to keep it off.
Feel free to read some of the other posts and health pages to get some ideas on how/where to start on a weight loss journey. In addition, stick around with us, we can help you out.
just start making good choices in what you eat and about exercise and then things will fall into place eventually...you ar so young, don't take diet pills, they are not worth it...start making good choices about your health at a young age and they will stick with you the rest of your life