The first thing you can do is listen to what she has to say about her drug use and about why she is using. It is always a good idea to encourage your friend to confide and seek advice from a trusted adult. If she doesn't realize the negative health effects drugs have on her body, brain, and life, there is a lot of information you can share with her that can be found on NIDA's website (www.drugabuse.gov). If she is already aware of the negative consequences drugs have on her health, school, family, etc., she may be prepared to make a change and seek treatment. You can help her find a doctor, therapist, support group, or treatment program by visiting the website www.findtreatment.samhsa.gov, or calling 1-800-662-HELP. If your friend is not ready yet to get help, don't give up on her. Keep reaching out, and hopefully some day soon she will be ready. Helping her go through the process of starting treatment, keeping in touch with her while she is in treatment, and supporting and encouraging her while she is in recovery are the best things you can do for your friend struggling with addiction.
It's hard to be in this situation, seeing a friend going down a dangerous path or suffering, and not being sure what you can do to help. First, let your friend know that someone cares about him. You can let him know you are concerned without being judgmental, and that there are people he can talk with in confidence. He may be more open to talk to a trusted adult or a medical professional if he feels that his privacy would not be violated. There are some resources for him that are anonymous—for example, the National Suicide Prevention Lifeline at 1-800-273-TALK. They don't just talk about suicide; they can help with a lot of issues including drug use, and can connect your friend with a professional close by. There is also a website with information about treatment programs: http://findtreatment.samhsa.gov/. Because talking with someone about their drug use can be uncomfortable, you may want to ask an adult you trust, like a teacher or coach, to help you figure out how best to help your friend.
There are lots of different kinds of treatments for drug use and addiction, and some work better than others. Research has shown that some treatments successfully help people stop using drugs and also help to solve other problems that tend to go along with drug use. It's hard to say why some celebrities keep going back to treatment. What we do know is that people who finish a treatment program that uses evidence-based practices tend to have a much better chance of staying off drugs for good, but that often involves major changes in lifestyle—changing where you hang out and who you hang out with. If people aren't willing to make those changes, they can easily fall back into using drugs. And even those people who do become abstinent can remain at risk for relapse for a very long time and may require ongoing support from community groups like Alcoholics Anonymous or Narcotics Anonymous, or multiple rounds of drug treatment. Addiction can be a chronic disease -- it involves changes in the brain that can persist even after a person stops using drugs. This can make a person vulnerable to relapse, and if that happens it becomes important to get them back into treatment as soon as possible, so that they can eventually recover fully and regain productive lives.
Not everyone has the same feelings after stopping drugs, but many say that they have a continuing urge to use, especially in the early days after quitting. And in some cases the triggers for this urge or craving may not even be consciously realized—passing by a place where drugs were once purchased or used, seeing an old friend with whom drugs were taken. One of the things that treatment does is help people to deal with the urges to use. And over time, these urges to use can weaken and become less frequent.