I actually just spoke to my drug counselor about this helping with my withdrawals, she says ABSOLUTELY stay away from that, not only is it NOT fda approved, nobody really knows what it's made of... I would tell your friend to stay away from the kratom, and try suboxone or methadone. I'm right now tapering down off of methadone (which isn't fun) but wanting to switch to suboxone, I'm definitely not saying those 2 are better than kratom, but it is doctor prescribed and you are pretty much being watched by doctors constantly-- I definitely hate having the "Crutch" but then again, every one is different. I would just mention that to him... see what he says.
Like I said in the beginning I was thinking about taking it to help with my withdrawals from tapering down off methadone, but my counselor said to abosolutely NEVER use or even try it just because nobody really knows what it is right now. I hope this helps just a little bit at least.
I have seen a few come here that are still having issues after coming off kratom. Neuro issues were the main one. The old saying goes, if it sounds too good to be true it usually is. I hope he listens to you and runs the other way from this stuff.