High-Potency Cannabis and Psychosis

Today’s weed is not the weed of the past.

Much of the cannabis sold today is far stronger in THC than it used to be. Research shows that using strong cannabis every day is linked to a much higher risk of psychosis. For some people, that can lead to schizophrenia.

This does not mean everyone who smokes will get sick. It means the risk is real, and it is higher than most families think.

What the research says

• About five times the odds. A large European study found that people who used high-potency cannabis (10% THC or more) every day had about 4.8 times the odds of a psychotic disorder compared with people who never used. (The Lancet Psychiatry, 2019)
• Young men are at highest risk. A study of over 6 million people in Denmark estimated that up to 30% of schizophrenia cases in men aged 21 to 30 might have been prevented by avoiding cannabis use disorder. (Psychological Medicine, 2023, via NIDA)
• Starting young raises the risk. Health Canada says the risk may increase when use starts before age 16, when use is frequent, and when products are stronger. People with a family history of psychosis or schizophrenia are at greater risk. (Health Canada)

Signs of psychosis to watch for

• Paranoia, or feeling watched or followed
• Hearing or seeing things others don’t
• Strange beliefs that don’t make sense
• Talking in a confused or jumbled way
• Pulling away from family and friends
• Not sleeping, or big changes in mood

If someone is a danger to themselves or others, call 9-1-1 or go to the nearest emergency department.

“It’s just weed”

That is the most common thing families hear. Cannabis is legal, so it feels safe. But legal does not mean harmless, especially for a young person using strong products every day.

What families can do

1. Don’t wait for a crisis. Early help leads to better outcomes.
2. Talk about what you see. Stay calm. Name the changes, not the person.
3. Get a medical opinion. A doctor can check for early signs of psychosis.
4. Know when it’s more than you can handle. If they refuse help and things are getting worse, a professional intervention can help.

This article is general information, not medical advice. Talk to a doctor about any health concern.