The active constituent is a trans-neoclerodane diterpenoid known as Salvinorin A, chemical formula C₂₃H₂₈O₈. Unlike most other known psychoactive compounds, salvinorin A is not an alkaloid — it does not contain a basic nitrogen atom.

Salvinorin A is the most potent naturally-occurring hallucinogen known. It is active at doses as low as 200 µg. Recent research has shown that salvinorin A is a potent and selective κ (kappa) opioid receptor agonist. It has been reported that the effects of salvinorin A in mice are blocked by kappa opioid receptor antagonists. This makes it unlikely that another mechanism contributes independently to the compound’s effects. Salvinorin A is unique in that it is the only naturally occurring substance known to induce a visionary state via this mode of action.

Extraction and purification of salvinorin A should only be attempted by qualified researchers with experience in chemistry and the proper laboratory equipment. Measurement of safe dosages is difficult and requires a sophisticated analytical balance, due to the extreme potency of salvinorin A. This potency should not be confused with toxicity, however: rodents chronically exposed to dosages many times greater than those humans are exposed to did not show signs of organ damage.

Many other terpenoids have been isolated from salvia divinorum, including other salvinorins and related compounds named divinatorins and salvinicins. None of these compounds has shown significant (sub-micromolar) affinity at the kappa opioid receptor, and there is no evidence that they contribute to the plant's psychoactivity. A thorough scientific review of the chemistry and pharmacology of this species is available