I am not going to tell you that I am the world's authority on kratom, but most of my colleagues in the field of drug prevention would tell you they have a negative view of this drug. Many people who are in recovery from opioids will crave a replacement, and many end up trying kratom. I have personally had them say to me that it is a nightmare, and only trading one addictive drug for another. Now, in a clinical setting, it might be useful, but I doubt it's usefulness when bought from a local source, and used recreationally. I also do not know of any reputable doctors who are promoting it's use.
There already medications - suboxone and vivitrol - that can be used in a clinical setting. When properly prescribed, within a carefully managed program, they can be very effective.
Even then, choose your doctor carefully. Many are out for money, rather than actually helping their patients.