London, January 16, 2026 – A standard unit for measuring cannabis potency-much like we use standard drink sizes for alcohol-could help people better understand their intake and identify those at risk of developing cannabis use disorder, according to a new study from the University of bath.
A ‘THC Unit’ for Cannabis? Experts Propose Safer Limits
As cannabis laws evolve globally, a standardized way to measure its strength is becoming increasingly important for public health.
- Researchers propose using “THC units” to quantify cannabis potency.
- A 0.45 gram joint can contain vastly different THC unit amounts depending on its strength.
- Adults shoudl aim for no more than 8 THC units per week to lower risk of cannabis use disorder.
- The study highlights the need for clear guidelines as cannabis becomes more widely available.
What’s a THC unit? A standardized measure of tetrahydrocannabinol (THC), the primary psychoactive component in cannabis, allowing for more informed consumption and risk assessment.
As more countries introduce laws permitting medicinal and recreational cannabis use, these standardized measures could be crucial for informing public health strategies focused on harm reduction. “As cannabis becomes increasingly available in legal markets around the world, it is more important than ever to help consumers make informed choices about their use,” says senior author Tom Freeman, Director of the Addiction and Mental Health Group at the University of Bath.
While some enjoy cannabis occasionally, others can develop cannabis use disorder (CUD), which can lead to meaningful health and social problems.
The CannTeen study, involving over 1,000 adults, found a strong correlation between THC consumption and the risk of disorder.
The study’s authors resolute that adults should not exceed 8 THC units per week to reduce the risk of developing cannabis use disorder. Seventy percent of the adults in the CannTeen study who exceeded this limit reported experiencing cannabis use disorder.
“The ultimate goal of our new guidelines is to reduce harm,” explains lead author Rachel lees Thorne,a psychology researcher from the University of Bath. “The only truly safe level of cannabis use is no use.However, for those who don’t want to stop or are unable to, we still want to make it easier for them to lower their risk of harm.For instance, a person might opt to use lower-THC products or reduce the quantity of cannabis they use.”
Public health researchers have welcomed the findings,suggesting a standardized measure of THC consumption could empower patients to moderate their intake and aid in further research. However, psychiatrist Marta di Forti of King’s College London points out that “cannabis, unlike alcohol, does not contain only one active ingredient but over 144 cannabinoids.”
“Nevertheless, THC units are, undoubtedly a very important and much-needed start,” she says.
The research is published in Addiction.