How can I help someone with a serious OTC habit?

Someone very close to me used to be a bright, warm and honest human being. For the past several months, this person has been taking OTC meds to get "high" and has deteriorated physically, socially and mentally, which is beyond heartbreaking. My question has more than 1 aspect:

1. Although this person is an adult, can the family intervene in any way?

2. The spouse of this person has become frightened over the person's erratic behavior and the possibility that the person may die from abusing these meds. Could the spouse get any kind of help from the police? The person's Dr. has been of little help, but simply says "don't take those things."

Thanks in advance for any information/advice or insights.