Background There is growing use of Salvia divinorum (SD), a psychoactive plant that produces hallucinogen-like effects through a kappa opioid receptor (KOR) mechanism. Little is known about KOR agonist effects in humans and about users of SD. Objectives To characterize the reasons, methods, and reported consequences of SD use. Methods Individuals reading SD-related pages of a drug-information website were invited to anonymously complete an online questionnaire if they had used SD. Results Participants (N = 500) were 92.6% male and 23.4 ± 8.7 (mean ± s.d.) years old. They had used a median of six times (range 1–250). 80.6% probably or definitely would use SD again. Most participants (92.6%) typically smoked or vaporized SD product. When smoked, the drug’s main effects were estimated to last 14.1 ± 12.8 (range 0.5–120) minutes. When asked to compare SD effects to other methods of altering consciousness, the most common answer was that SD was unique (38.4%). 25.8% reported persisting (≥24 h) positive effects (often described as increased sense of well-being) on at least one occasion. 4.4% reported persisting negative effects (most often anxiety). Conclusions SD is typically smoked, acute effects are brief, and persistent adverse effects are uncommon. In addition to acute hallucinogenic effects, SD may produce subacute increases in subjective well-being. Such a subacute effect would be unusual for a drug that is used non-medically, as withdrawal from other drugs typically either does not affect mood or causes dysphoria. Findings from this convenience sample should be confirmed and extended using surveys of random samples and controlled clinical studies.