Weed and Anxiety: What the Research Shows and What to Do

Anxiety is a known short-term effect of cannabis: Health Canada lists anxiety, fear or panic among the effects cannabis can have on the brain, along with a faster heart rate and, in some cases, paranoia, delusions or hallucinations.

Dose matters. CAMH says stronger doses of THC can intensify the effects people want but can also produce anxiety, paranoia and panic. It lists other things that shape a high: THC potency, how much and how often you use, how you take it, your mood, expectations and surroundings, your age, any medical or mental health conditions, and whether you use alcohol or other drugs at the same time.

Edibles add a timing trap. CAMH says eaten cannabis can take up to 2 hours to show effects, so people may think it is not working and take more, and suggests waiting about 4 hours before deciding on another dose. The guide to edible dosing covers the timing in more detail.

Health Canada says daily or near-daily cannabis use over time can increase your chances of developing anxiety and depression disorders, and that people who use this often may become dependent, have trouble regulating their emotions and experience anxiety and depression more often.

Ontario data point the same way. A 2024 study in eClinicalMedicine by researchers at The Ottawa Hospital, the University of Ottawa and ICES followed more than 12 million people with no previous hospital or emergency care for an anxiety disorder. Within 3 years of an emergency department visit due to cannabis, 12.3% had an emergency visit or hospital stay for an anxiety disorder, compared with 1.2% of the general population, a 3.7-fold higher risk after adjustment. Young men had the largest relative increase.

A separate 2024 Ontario study, led by a McMaster University researcher with colleagues at CAMH and ICES, found a modest link between youth cannabis use and later health care for mood and anxiety disorders, but no clear pattern of more use bringing more risk.

Researchers still debate cause and effect. A 2024 critical review found cannabis use and cannabis use disorder are both linked with anxiety disorders, but concluded the link is best explained by people with anxiety turning to cannabis to self-medicate, rather than cannabis causing anxiety disorders.

Some people use cannabis to cope with stress, anxiety or low mood. Health Canada says cannabis use has not been found to improve mental health over time, and that people are more likely to recover from long-term anxiety and depression if they reduce or stop using it. CAMH adds that there is no good evidence cannabis helps with anxiety or depression in the long term.

A 2019 systematic review and meta-analysis in The Lancet Psychiatry found scarce evidence that cannabinoids improve anxiety disorders, depression, post-traumatic stress disorder, ADHD, Tourette syndrome or psychosis. Few trials tested CBD or medicinal cannabis at all, and THC-based medicines led to more side effects and more people dropping out because of them than placebo did. The authors concluded there is not enough evidence to guide the use of cannabinoids for mental disorders.

Canada's Lower-Risk Cannabis Use Guidelines do advise choosing products with low THC and a high CBD-to-THC ratio to reduce health risks. That is risk-reduction advice for people who already use cannabis, not evidence that CBD, a particular strain or a terpene profile works for anxiety.

Talk to a doctor or pharmacist if cannabis keeps making you anxious, if you use it to manage anxiety, or if you find it hard to cut down. Health Canada lists signs of dependence that include cravings, trouble cutting down, needing more for the same effect and feeling restless, moody or anxious when not using. CAMH says treatment for cannabis use disorder includes talk therapy to help with cravings and prevent relapse.

Free, confidential support listed by Health Canada: