Occasional male cannabis users feel stronger effects than women, study suggests

Men who use cannabis occasionally may feel stronger effects from the drug than women with similar use habits, according to new research. The study from UCLA Health in the United States was published in the journal Neuropsychopharmacology.

The study included 44 healthy adults between the ages of 21 and 55, evenly split between men and women. Researchers divided the participants into frequent cannabis users and occasional users.

Each participant took part in three separate sessions. In them, they were given cannabis with no THC, cannabis with a lower amount of THC and cannabis with a higher amount of THC to smoke. At the time, they did not know which one they were receiving.

Among those who used cannabis occasionally, men reported feeling more high, more sedated and more 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.

Blood THC levels alone did not appear to explain the difference. Men and women who used cannabis occasionally had similar peak THC levels, even though the men reported stronger effects.

The pattern was different among people who used cannabis more often. 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 the effects of cannabis. Dr. Ziva Cooper, the study's principal investigator and director of the UCLA Center for Cannabis and Cannabinoids, said in a press release that much of what was thought to be known 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," she added. The 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 in the release, "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 researchers acknowledged several limitations to the findings. The study was small, with just 44 participants, and several of the findings involving occasional male users came from exploratory analyses, meaning they need to be confirmed in larger studies.

The cannabis used in the experiment contained 4 percent or 10 percent THC, which researchers noted is weaker than many cannabis products sold today, where THC levels are commonly 20 percent 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 risk.