I took 0.25 mg once, and I felt so hung over the next day, I could hardly do anything. The rest went into the "biohazard" box. I just don't think I can tolerate that type of medicine. I took 5mg of Ambien, once, and, had hallucinations in addition to feeling hung over. That also went into biohazard.
More seriously, it is illegal to share any prescription medication. Technically, it is practicing medicine without a license. I would get put in jail if I didn't have a valid license and continued to practice medicine, so, I suspect that if a person got caught, they could also be prosecuted.