For many years, the main focus of cannabis consumers and patients when it came to cannabinoids contained in the cannabis plant seemed to be tetrahydrocannabinol (THC). THC is largely responsible for the euphoric effects associated with cannabis consumption. However, in recent years, other cannabinoids have increased in popularity among consumers and patients, particularly cannabidiol (CBD).

A team of researchers based in Canada and affiliated with the Université de Montréal recently conducted a study examining how co-administration of CBD and THC impacts the plasma availability of THC and its active metabolite 11-OH-THC. The study’s findings were published in the journal Neuroscience and Biobehavioral Reviews.

The researchers conducted a systematic search of “acute dosing trials that administered a) a single, fixed dose of THC and b) a matched dose of THC co-administered with CBD.” In total, the researchers incorporated results from 14 unique trials into their analysis.

“Our results show that co-administration of CBD can significantly increase blood levels of 11-OH-THC, the active metabolite of THC, an effect that is highly dose-dependent for both CBD and THC.” the researchers found.

“While it remains to be determined how CBD-related increases in THC and 11-OH-THC levels translate into behavioural or adverse effects, the findings from the meta-analysis highlight the need for caution and nuance when broadly encouraging high doses of CBD in combination with THC.” the researchers concluded.

Several previous studies have found the combination of CBD and THC to be effective at treating various health conditions. For example, a team of researchers based in Brazil and affiliated with the Federal University of Paraná reviewed data from multiple research databases “to evaluate the efficacy and safety of cannabinoids for the treatment of MS-related spasticity,” finding that the use of CBD:THC extracts yielded improvements among patients.

A separate study in Iran focused on a sublingual spray containing CBD and THC to see if it helped patients diagnosed with type 2 diabetes. The researchers determined that the CBD:THC spray improved the patients’ blood sugar and cholesterol levels.