Background: Mitragyna speciosa (Korth.) or kratom is an indigenous medicinal plant of Southeast Asia. Kratom is widely reported to have dose-dependent effects based on available literature, but to our knowledge, this has not been established conclusively. Objective: This study sought to evaluate if kratom use produces dose-dependent effects, with a stimulant effect at low doses and a sedative effect at high doses, in a sample of regular kratom users. Methods: A total of 63 regular kratom users participated in this cross-sectional study. The Brief-Biphasic Alcohol Effects Scale (B-BAES) was used to determine subjects self-report kratom use experiences. Results: Almost all in the sample were male (98%, n = 62/63), and the majority of subjects were Malays (94%, n = 59/63). The mean age of the subjects in the sample was 43.8 years (SD = 12.1). Seventy-five percent (n = 47/63) have >5 years kratom use history, and 65% (n = 41/63) consumed >3 glasses of kratom daily. Results from first test showed no significant difference in the stimulant (t61 =0.371, p < .331) and sedative effects (t61 =502, p < .759) between those who consumed >3 glasses a day or less than this amount, regardless of duration of use. In the second test, no significant differences in the mean scores were found among those who consumed >3 glasses daily or less than this amount among short-term or long-term uses. Conclusions: Daily kratom use produced both stimulant and sedative effects but they were not statistically significantly associated with the dose consumed, both among short-term and long-term users in our sample.
Keywords: Kratom; Malaysia; dose-dependent effects; mitragynine; stimulant.