I'll start...
I experienced hepatic toxicity after using kratom. After a week and a half stint of daily kratom use to halt withdrawals from a small hydrocodone physical dependence, I started vomiting and was very dizzy. Went to the ER, and my enzymes were severely elevated.
After a stay of a few days, I was releaseed. Under doctor's orders, I restarted taking the hydrocodone. After a month, I was retested, and my enzyme levels were only a few points above normal levels. I ran out of my hydrocodone and stupidly used kratom again for about a week. I started having the same symptoms, so I abruptly stopped using. It has been two days with no kratom use, and I am starting to feel better.
I take Zoloft daily as well, so it is possible that kratom reacts badly with SSRI's. It is also possible that it was just a strange, idiosyncratic reaction. However, from my experience, I no longer see kratom as a harmless nutritional supplement. It can also be dangerous.