This plant belongs to family rubiaceae and its leaves have been used by thai tribes as psychoactive.The labourers in some parts of thailand still chew it as an stimulant while as,it causes numbness in the mouth of normal people;i mean those who are not addicted to it. Some known sideeffects are annorexia,insomnia,dryness of mouth. Some tribals use it as antidiahorrea. Some people claim it reduces the withdrawl effects of opium based drugs but scientific studies yet to prove that. This is what i know of kratom at present.