OBJECTIVES: Today, cannabis contains significantly higher levels of THC than in previous years. Since past research may underestimate its health effects with higher potency, this study examined the impact of elevated levels of tetrahydrocannabinol (THC) in cannabis products on the development of psychosis, cognitive function, driving impairment, hyperemesis, and pregnancy outcomes, due to the growing accessibility and potency of these products following legalization in the United States.

METHODS: PubMed and Web of Science were utilized for a narrative review focusing on THC potency and its adverse effects up until January 2023. The search incorporated keywords related to THC concentration, cannabis products, and various adverse effects including driving impairment, hyperemesis, pregnancy and lactation issues, cognitive activity, adolescents, and psychosis.

RESULTS: The study found a strong association between daily, high-potency cannabis use and an increased risk of psychosis. Adolescents using high-potency cannabis may experience psychotic symptoms six years earlier than non-users. Habitual users, when switching to more potent forms like medicinal marijuana or hash oil with over 90% THC, can develop psychosis. Daily users have a threefold higher risk of psychotic conditions. High-potency marijuana impairs executive function and motor control, with effects lasting up to six hours and intensifying with higher THC doses. Marijuana use during pregnancy and lactation is linked to low birth weight, preterm birth, and neurological issues in newborns.

CONCLUSIONS: Given the evidence of harmful effects associated with high-potency cannabis, there is a need for reevaluation of cannabis product potency regulation following its legalization in the US. Additionally, states considering future legalization should prioritize understanding the implications of increased consumption of higher potency cannabis.