In this study of infrequent cannabis users, researchers evaluated effects of high dose Δ9-THC when ingested alone versus with CBD. They found that when Δ9-THC was ingested with CBD the effects of Δ9-THC were more pronounced than when Δ9-THC was ingested alone, and that cognitive and psychomotor impairments were greater. Heart rate increased more with the combination of CBD and Δ9-THC and overall greater adverse subjective drug effects were noted.
Full article title: Assessment of Orally Administered Δ9-Tetrahydrocannabinol When Coadministered With Cannabidiol on Δ9-Tetrahydrocannabinol Pharmacokinetics and Pharmacodynamics in Healthy Adults: A Randomized Clinical Trial
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