How small is a microdose, how big is a macrodose? Clarifying the lexicon of psychedelic research and treatment

Abstract

Nutt et al. recently proposed a common lexicon for psychedelic science including dosing categories for different forms of psychedelic use across multiple substances. Although common dosing terminology is an important advance, this paper identifies four challenges with Nutt et al.'s proposed categories. First, microdosing was defined as subperceptual; however, in both scientific and naturalistic settings, dose ranges typically described as ‘microdoses’ are associated with some subjective effects. Second and relatedly, Nutt et al. claimed that microdoses are indistinguishable from placebos, but empirical data show that participants usually can distinguish between these. Third, the proposed dosing category labels are in some ways inconsistent with the terminology commonly used in the scientific literature and the broader psychedelic community. Fourth, dosing categories were mostly defined as point estimates, leaving considerable ambiguity about how to describe doses that fall in between the suggested categories. To address these challenges, I propose an alternate, simplified dosing schema that aligns category labels (macrodose, minidose, and microdose) with common cultural norms and defines each by clear dose ranges. This new schema builds on the important work of Nutt et al. to provide a nuanced dosing framework for psychedelic science.