Did in the past and as from yesterday I am back on kratom. Can't say that I am maintaining but I will be taking it every day so it amounts to the same. I am using it for chronic pain and depression that comes from not being able to do things cause of the pain. Hope it will give me enough of relief to start enjoying life. Last time I was on it was few last months of previous year. Kicked it without some serious issues (comparatively speaking...comparing to tramadol, morphine oxycodone and buprenorphine).
Kratom has its own set of upsides and downsides. If you stick to plain leaf and don't go to extracts than your stomach will make sure the amount you take is somewhat reasonable. It is opioid but you will never get some serious nodding high. When one knows that he can't get much higher then compulsion to take more is not there. While it works, it is very nice subtle substance that is legal in most of the Western world and it satisfies opioid cravings to a certain extent. Although in that regard it can be a double edged sword. Not as strong of a painkiller as I would have liked but comparable to low dose of oxycodene of 5mg (max 10mg), which is nice. I wouldn't advise to dose more than 10 grams at once cause it could lead to stomach pain ad dysphoria. I believe that kratom is opioid agonist, partial opioid agonist and even has some alkaloids that are opioid antagonists. Have been reading about it being opioid antagonist also, and it would make sense based on my experience with diminishing effects when dosages are upped.
Regarding dosing I would advise 4-8 grams range. Some people say that strains are irrelevant while other swear by them. I would say that one should find a reputable source, strain(s) that he likes the most and stick with that. I believe that you would like something similar to classical opioid and that would be "red thai" or "red borneo" in my book. I dose 4-6 grams of red thai or red borneo (or mix) when I am only after pain relief, while I find green malay best for morning/work hours. But again, that will depend on your supplier and preferences. Try things out at first and stick with best you find.
I would say that going over 40 grams of kratom daily is not advisable, and would actually say that 4-5 times of 4-8 grams is maximum recommended dose. You will have to dose every 4 hours after dependence is created cause kratom is not long lasting so that is a minus. Withdrawal tend to be more psychological than physical and is short lived. If one has access to some pregabalin and benzos for a week the whole withdrawal can be almost painless. I have heard people mention black seed oil for the withdrawal. I have bought it but have not used it in the past.
@negrogesic will tell more about that and I will be all ears when he does.
If you are in States try to use agmatine as it supposedly helps with tolerance (or it potentiate kratom, not 100% sure). I am truly sorry that I can't test it. Some idiots have put it under control in EU with some "food act" so I can't order it at all. Again negrogesic should comment on that.
That's all I can contribute for now. If you have some further queries I will be happy to share my experience.
