drugs and my sister

I'm not really sure what to do about this, it's really concerning me. I've known for years that my sister does drugs, I thought it was just weed, then found out it was harder drugs too. She told me a couple of weeks about this drug she was taking and I did a bit of googling and found that even though it's legal (though illegal in a lot of countries) people have died from taking it. Of course this has made me very worried. About 5 years ago my best friend was murdered, I haven't really got over it, I cry everytime I think about him or see pictures of him or anything, I even partly blame myself for not calling him that night because things could have been so different. But now I'm worried I might lose my sister too and it would crush me. I love her of course, she made my childhood bareable, and I know it's her life she can do what she wants but I don't want to lose her or for her to get ill from all the drugs. I'm not sure what I should do.

Buy her a lovely handbag (to soften her up) and sit her down with a nice cup of tea and a Jaffa cake. Just tell her how you feel and explain how much you love her, and to stop this drugs piffle.

I assume you're talking about mephedrone. It is a very, very dangerous drug. It has structural similarities to other substances which cause cardiac fibrosis, as it is a 5HT2B agonist. It is highly likely that if it is used excessively, it will cause serious heart problems in quite few users. Due to the extremely moreish nature of it, it is likely that large quantities will be used. I know people taking multiple grams in an evening. You need to make her aware of the dangers in a calm, and non patronising way. I would concentrate on emphasising these dangers, as it is a very nasty drug indeed.

Your friend was murdered over drugs?

Let her make her own mistakes? There is a lot of misinformation and stigma surrounding drug use, when most drugs are less harmful than alcohol and tobacco. If you're concerned, then let her know that you are worried about her because you are her brother and it's your place to be concerned, but I certainly wouldn't lecture them or tell them to stop.

EDIT: as above a cup of tea and a jaffa cake would help too. Great suggestion!