Scientists tested the belief that women are more sensitive to cannabis, and the group that felt it most turned out to be men who rarely use

Many people believe women are more sensitive to cannabis than men, an idea based largely on animal research. Researchers at the UCLA Center for Cannabis and Cannabinoids designed an experiment to test it directly. Forty-four adults who used cannabis either occasionally or frequently each smoked a placebo cigarette, a moderate dose and a stronger dose about three times as large, in random order and without knowing which. The team measured blood THC and how high, sedated and impaired each person felt.

Sex alone did not predict who felt the strongest effects. The group that reacted most was men who used cannabis occasionally. They reported feeling more high, more sedated and more impaired than anyone else, along with more unpleasant effects such as anxiety, and they were the only group whose heart rate rose significantly after smoking active cannabis.

Women who used cannabis occasionally did not show the same heightened response, even though their blood THC levels were about the same as the men’s. Among frequent users, men and women responded in similar ways.

“Much of what we thought we knew about sex differences in cannabis effects came from animal research and from human studies that pooled data from different trials,” said principal investigator Ziva Cooper, director of the UCLA Center for Cannabis and Cannabinoids. “As more women use cannabis, including for women’s health conditions, we need evidence from studies designed to include them.”

Blood levels did not explain the differences. Men who used frequently tended to have the highest THC levels, yet they felt fewer effects than men who used occasionally, a sign of tolerance. The researchers suggest women may build tolerance with less use than men, an idea larger studies will need to test.

The second finding is about misuse risk. Regardless of sex, frequent users were more likely than occasional users to choose to pay for more cannabis during the study, an exploratory measure of its addictive pull.

“Sex and cannabis use history can both shape how someone experiences the effects of cannabis,” said lead author Stephanie Lake. “And studying both together is key to understanding who is most at risk of higher-risk, unpleasant, or beneficial experiences from cannabis.”

The researchers accounted for hormone levels in women, which can affect how cannabis is processed. Their team is now studying high-potency products and adults 55 and older, whose cannabis use is rising. Cannabis does not always do what people expect, as a 35-year study of cannabis and sleep also found.

For occasional users, the practical takeaway is that dose expectations can be off, especially for men who rarely use: the same amount can hit harder than expected, with anxiety and impairment that matter for driving and safety.

There are limits to what this shows. With 44 participants, the study was small, and the groups split by sex and use frequency were smaller still. It tested smoked cannabis in a lab, not edibles or high-potency products, and the effects were short-term. The study was funded by the US National Institute on Drug Abuse.

Source

Lake S, et al. “Sex- and frequency-dependent acute pharmacokinetic and pharmacodynamic effects of smoked cannabis: a randomized controlled trial.” Neuropsychopharmacology, 2026.
DOI: 10.1038/s41386-026-02571-3