Men and women who smoke marijuana may experience different effects, study suggests

A UCLA Health study published in the journal Neuropsychopharmacology suggests that men and women who use cannabis occasionally may experience different effects from the drug. The study included 44 healthy adults between the ages of 21 and 55, evenly split between men and women. Researchers divided participants based on whether they used cannabis frequently or occasionally. Each participant took part in three separate sessions where they smoked cannabis containing no THC, a lower amount (4%), or a higher amount (10%), without knowing which they were receiving.

Among occasional users, men reported feeling more high, sedated, and impaired than women with similar use habits. The men also reported more unpleasant effects, including anxiety, and their heart rate rose significantly after using active cannabis. Despite these stronger subjective effects, men and women who used cannabis occasionally had similar peak THC levels in their blood.

The pattern differed among frequent users. Men and women in the frequent-use group generally responded similarly to active cannabis. Frequent users were also more likely than occasional users to say they liked the effects, wanted to use cannabis again, and chose to take more during the study, regardless of gender.

The findings challenge some previous research suggesting women may be more sensitive to cannabis effects. Dr. Ziva Cooper, the study's principal investigator and director of the UCLA Center for Cannabis and Cannabinoids, said in a press release: "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. When we designed a study to look at sex and frequency of use at the same time, and controlled for hormones, the picture changed." Researchers controlled for menstrual cycle timing among the women in the study, who were not using hormonal birth control.

Lead author Dr. Stephanie Lake, a researcher at the UCLA Center for Cannabis and Cannabinoids, said: "Sex and cannabis use history can both shape how someone experiences the effects of cannabis. Studying both together is key to understanding who is most at risk of higher-risk, unpleasant or beneficial experiences from cannabis."

The study authors noted several limitations. The sample size was small, with just 44 participants, and several findings involving occasional male users came from exploratory analyses that need confirmation in larger studies. The cannabis used in the experiment contained 4% or 10% THC, which researchers noted is weaker than many products sold today, where THC levels are commonly 20% or higher. Researchers said larger studies are needed to better understand whether men and women develop tolerance to cannabis differently and how those differences could affect the risk of cannabis use disorder.