Hundreds of human laboratory studies of THC have been conducted. Although most studies of oral THC used a typical dose of around 10 mg, some studies need to test higher doses to reach their research objectives. Given that higher doses are associated with stronger adverse events, what is an ethically acceptable limit of oral THC doses?

This question was examined in a recent analysis by researchers at Verdient Science in collaboration with Dr. Marilyn Huestis. Dr. Huestis spent 23 years at the National Institute of Drug Abuse performing human laboratory trials of THC, and is currently a Senior Fellow at Thomas Jefferson University.

This article reviewed studies that administered oral THC doses of 30 mg or higher, aiming to understand the tolerability, subjective effects, and pharmacokinetics of high-dose THC. A comprehensive literature search found 27 publications from 17 laboratory studies, with doses ranging up to 90 mg for single doses and 210 mg per day for multiple doses. The analysis suggested that high-dose THC was generally well tolerated at single doses up to 50 mg, with transient mild to moderate adverse events such as nausea, vomiting, anxiety, paranoia, and sedation. Participants with frequent cannabis use appeared to tolerate high-dose THC better, with no serious adverse events reported.

This analysis is expected to guide future studies of high-dose oral THC, including on study design, participant selection, and inclusion of assessments such as pharmacokinetic and subjective effects. The article titled “Tolerability of High-Dose Oral Δ9-THC: Implications for Human Laboratory Study Design” was published in the peer-reviewed journal Cannabis and Cannabinoid Research.