A new study has revealed that individuals who begin using cannabis to manage conditions such as pain, anxiety, or depression are more likely to develop paranoia than those who consume the drug for recreational purposes. The findings highlight the complex relationship between cannabis use and mental health, particularly among vulnerable groups.
The research, published in BMJ Mental Health and led by King’s College London, analysed data from 3,389 adults with no history of psychosis who participated in the Cannabis&Me survey. Results showed that people who turned to cannabis for self-medication had higher paranoia scores compared to those who used it casually, for fun, or out of curiosity. The study also noted that individuals with minor psychotic symptoms were particularly at risk.
The survey found that the average respondent consumed around 206 units of THC, the psychoactive compound in cannabis, each week—equivalent to 10–17 joints. However, those using cannabis to cope with depression or anxiety consumed significantly more, at 254.7 and 248 units respectively. This heavier consumption was closely linked with greater reports of paranoia.
While medicinal cannabis prescriptions are available through the NHS in England, they remain highly restricted, with eligibility limited to patients with rare epilepsy, chemotherapy-related nausea, or certain forms of multiple sclerosis. Despite this, private clinics across the UK are offering cannabis to patients for conditions like pain, anxiety, and depression—ironically, the very issues most closely tied to increased paranoia in the study.
He stressed that contrary to online claims, cannabis is not broadly medicinal and that its misuse can fuel mental health challenges, especially paranoia.
Dr Emily Finch of the Royal College of Psychiatrists’ addiction faculty echoed these warnings, noting that cannabis is not only addictive but can lead to severe psychiatric issues. She emphasized that daily use of high-potency cannabis significantly raises the risk of psychosis, depression, and anxiety. Adolescents, she added, are particularly vulnerable.
A separate study in Psychological Medicine found that over half of cannabis users surveyed had experienced childhood trauma, with those reporting abuse scoring 35–40% higher on paranoia measures. Moreover, individuals with a history of sexual abuse were more likely to consume higher amounts of THC, compounding their risks.
Together, these findings underscore the urgent need for better education, prevention, and early intervention strategies. Cannabis use is widespread, but its risks—particularly the potential for paranoia and other mental health harms—remain underappreciated. For policymakers and health services, the message is clear: tackling cannabis misuse must go hand in hand with addressing the mental health needs of those most at risk.