Tolerance. Also, you're taking too much. There are lots of alkaloids in Kratom and a nice balance of their effects is at the 4-6g range: the sweet spot, imo, taken only once in a day and not redosed at all.
I have to point out that IMO your thinking the 4-6 gram range is where you get the best effects is PURELY your own tolerance cause I get ZERO effects from 6 grams.
I have a MASSIVE Kratom tolerance and anything less than 10 grams I get pretty much no effect at all and it takes 14-18 grams for me to get the really good kind of high I want.
I kind of don't understand how people have been able to keep their tolerances low.
I guess I just kept raising my dosage and maybe if I'd kept it low from the beginning it never would have happened but I didn't so now I think it's too late for my tolerance to probably ever get as low as 6 grams again.
The last time I stopped for 90 days before that I was up to needing to dose an ounce in a single sitting for a good high and then it dropped back down to 14 grams after 90 days so for me I couldn't imagine how long I'd have to stop to get back to 6 grams if it could EVER even happen.
Now I am trying to take AT LEAST a 6 month break from it, maybe more, not for tolerance but because on my off days I find myself unable to be productive and practice martial arts seriously when in WD which is something I'm really into which makes me wonder if maybe it lowers testosterone because I found myself literally INCAPABLE of forcing myself to workout when I had ANY kind of Kratom in my system or for a few days after dosing.
I know it was chemical because I can make myself workout even when very tired or late at night but I just couldn't force myself to work out if I had recently dosed Kratom.
It was like I just literally lacked the chemical necessary to work out...which I am guessing is testosterone.
Lots of people think that it must do that since all other opioids and opiates seem to do that.
Other than that I absolutely love Kratom and it doesn't have too many bad side effects for me other than giving me insomnia if I dose close to bed time but I got good at dosing early so that wouldn't happen, but I just can't miss my workouts any longer so I have to take a long break.