I really do not understand how people seem willing to swallow literally anything at all, investing a childlike trust into the concept that its "herbal", and of course we all know that herbal stuff is completely safe dont we?
There are all sorts of problems buying supplements or pharmaceuticals over the internet.
1.Lack of any proper data on possibly clinically significant side-effects.
2.Accessing supplements or medication that may be banned in the UK.
3.The very high, very real chance that you are paying good money for fake tablets.
Your mates daughter already sounds unhealthy, and maybe borderline with respect to eating disorders of one sort or another.. Taking alleged slimming pills ordered online with no means of verifying the manufacturer or the ingredients and possible side effects is just plain silly.She is already on prescribed medication but is taking pills without checking whether there could be serious interactions? It is an incredibly high-risk lifestyle.
We are all free to make our own decisions obviously - but IMO your friend should be stepping in to try and protect their daughter from these risky actions.