High-concentration THC cannabis products are consistently linked to worse mental health outcomes, especially psychosis or schizophrenia and cannabis use disorder. Among 99 studies (over 221,000 participants), 70% of non-therapeutic studies found unfavorable associations with psychosis or schizophrenia, and 75% found unfavorable associations with cannabis use disorder. For anxiety and depression, about half of non-therapeutic studies reported unfavorable associations, particularly in healthy populations. Some therapeutic studies suggested benefits for anxiety (47%) and depression (48%), but these findings were low-quality and inconsistent. More than 95% of the studies had moderate or high risk of bias.
A meta-analysis of 15 randomized controlled trials compared low-dose ketamine with morphine for acute pain in the emergency department. The analysis suggests that low-dose ketamine provides comparable pain relief to morphine, with a similar onset of action. However, ketamine was associated with a higher incidence of minor, transient side effects such as dizziness, nausea, and psychomimetic effects, while morphine carried a greater risk of respiratory depression and hypotension. The findings indicate that low-dose ketamine is a viable alternative to morphine for managing acute pain in the emergency setting, particularly when avoiding opioid-related adverse effects is a priority.