Microdosing has exploded in popularity over the past six years. A microdose can be 1/10th or less of a recreational dose and users will often microdose regularly every 3 or 4 days over an extended period of time. Due to the very low dose, microdosers do not usually report the dramatic cognitive and perceptual changes that typically characterise psychedelic experiences, rather immediate effects are reported to be very subtle and sometimes barely noticeable. Despite this microdosers make a wide variety of claims for the benefits of microdosing, including improved vitality, positive mood, increased attention and greater creativity. The idea that substances such as LSD and psilocybin might be effective at very low doses has helped shift psychedelics from being a taboo topic to something that is favourably discussed in all kinds of mainstream media outlets and dinner party conversations around the world. But what do we really know about microdosing? Are the claims of microdosing proponents justified? Or, as some recent research has suggested, is the effect entirely due to placebo?