My sister has detoxed from Heroin without medical treatment, but she was in jail. I would be less concerned about the safety of opiate detox than about the likeliness of relapse. Opiate withdrawal is about as bad as it gets, I'm told, and detox is only the very beginning of recovery. My sister didn't make it a single day once she was released.
Alcohol withdrawal, on the other hand, absolutely requires medical attention. I have heard that people can die from acute alcohol withdrawal. Scary stuff.
I'm very sorry to hear about your daughter, I'll keep you and her in my prayers.
