Depends what kind of rehab. My bestfriend was in rehab as well for cocain. He got arrested and sentenced to it. But he was sent to full rehab and was not aloud any contact with his friends only familiy because they think it would cause him to relapse. But there are out patient rehabs which you can talk to them so idk which one he/she is in. Goodluck and if you dont drink/do drugs make sure you keep there head up and communicate with em when they get out. But if you do, stay away from them for a while because you will cause them to relapse.