Study proposes THC units to measure when cannabis consumption becomes excessive

British researchers have established the first concrete limits on cannabis consumption based on THC units, providing parameters that can help healthcare professionals and consumers measure when substance use is associated with a higher risk of cannabis use disorder (CUD).

The new system proposes that the total amount of THC ingested per week, not just frequency of use, be counted in standard units, each corresponding to 5 milligrams of THC, the plant's main psychoactive substance.

This approach is similar to the use of standard units for alcoholic beverages, which already guide safe consumption guidelines in various countries.

The research, published in the scientific journal Addiction, used data from the longitudinal study CannTeen, which followed 150 cannabis users for one year. Researchers collected detailed usage patterns and applied clinical diagnoses to identify cannabis use disorder at the end of the period.

THC: new weekly usage limits and risk of disorder

According to the study results, average weekly consumptions above approximately 8 THC units (about 40 mg of THC) were associated with a significantly higher risk of cannabis use disorder in young adults (26–29 years), compared to lower consumptions. For teenagers (16–17 years), this cutoff point was estimated at about 6 units per week.

Researchers also identified that higher limits, for example, about 13.4 units per week, were associated with moderate to severe forms of disorder in adults, a pattern that suggests a relationship between THC quantity and problem severity.

Cannabis use disorder (CUD) is defined by criteria from the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and is characterized by difficulty controlling use and continued use despite negative consequences in social, professional, or family life.

The study also emphasized that these THC units are an initial tool to estimate when the risk of CUD increases, but the only completely risk-free level is abstinence. This is because many cannabis products vary widely in potency and consumption method (smoking, vaporizing, edibles, etc.), which can alter actual THC exposure even with the same number of units consumed.

These data can support preliminary clinical assessments and prevention strategies, encouraging healthcare professionals to inquire about weekly THC quantity instead of just days of use, and providing a more comparable parameter between different consumption methods and products available on the market.

With information from DW.