I agree with what the other posters have said - that you can't make your sister do anything, and trying to force her to do anything could backfire.

My suggestion is to get information for her about NA (narcotics annonymous) and AA (alcoholics annonymous)meetings in your area. Information such as meeting places and times, with an offer to go with her if she wants/needs support, but also telling her that you will respect her privacy to go to the meetings alone if that is her choice.

I know your post mentioned drugs use and not alcohol use, but the reason I mention AA in addition to NA is because there are often a lot more AA meeting available, and because AA does address drug issues in addition to alcohol since many people have duel addiction (drugs and alcohol).

My other suggestion is for you to find local Al-Anon meetings in your area for you and your family (parents, other siblings) to attend. Al-Anon is for people who are friends or family with an addict and/or alcoholic. They can help you and your family learn the do's and don'ts of supporting and loving a person who is drug or alcohol addicted (whether the person is still using or is in recovery).

Take care,
Liz