Simplified metabolic pathway of ∆9-tetrahydrocannabinol (THC), or ∆1-tetrahydrocannabinol, under the monoterpenoid naming system, in humans. Both 11-hydroxy- ∆9-tetrahydrocannabinol (11-OH-THC), or 7-hydroxy- ∆1-tetrahydrocannabinol, and 8-hydroxy- ∆9-tetrahydrocannabinol (8-OH-THC), or 6-hydroxy- ∆1-tetrahydrocannabinol, are active metabolites.