Smoked Marijuana and Oral THC Produced Similar but Not Identical Effects in Frequent Users
A controlled residential study found broadly similar effects from repeated smoked marijuana and oral THC in frequent cannabis users, with differences in subjective responses and the days after exposure. The small, highly experienced sample limits generalization to occasional users.
The comparison occurred within the same volunteers
Eleven healthy volunteers who reported averaging six marijuana cigarettes daily completed an 18-day study. Smoked marijuana and oral THC were each administered over three consecutive days, separated by placebo days, using a double-blind, double-dummy design. The comparison concerned specified study products and schedules, not every edible or smoked formulation.
Food intake and subjective effects overlapped
Both conditions increased food intake across the three treatment days and produced similar ratings for effects such as feeling high or mellow. Some smoked-marijuana effects were more pronounced and less prone to tolerance. Negative ratings during subsequent days were reported after smoking but not after oral THC under this protocol.
Limited psychomotor effects are not proof of driving safety
The study reported little effect on the psychomotor tasks used. That result belongs to these frequent users, administered regimens and laboratory measures. It cannot establish an absence of impairment for inexperienced users, different doses or more demanding real-world activities.
The value of this experiment is its direct within-person route comparison. It supports partial similarity with meaningful differences, rather than dose equivalence across products. Route, exposure history and the period after administration all remain important when interpreting a reported cannabis effect.
Related: interpreting cannabis tolerance claims.
Research cited
Hart CL; Ward AS; Haney M; Comer SD; Foltin RW; Fischman MW. Comparison of smoked marijuana and oral Delta(9)-tetrahydrocannabinol in humans. Psychopharmacology (2002). doi:10.1007/s00213-002-1231-y. Findings discussed from the study abstract.
