The purpose of the present study was to examine sex differences in cannabis use and effects using a large sample of recreational and medical cannabis users. Overall, the results indicated that there are small but significant sex differences in cannabis use patterns, acute effects, and withdrawal effects. In contrast, only trivial sex differences in medical cannabis use, and in perceived efficacy of medical cannabis, were detected.

Consistent with previous research our findings indicate that men use cannabis more frequently and in higher quantities than do women. We did not replicate previous findings that men are more likely to initiate use at a younger age.^18–20 This may be indicative of recent changes in the socio-cultural perception of cannabis use among female adolescents. However, our results do provide evidence that women are twice as likely as men to initiate use after the age of 30. This may reflect new trends in diminishing stigma toward cannabis use and decreases in older women's perceptions of risks associated with cannabis use. Alternatively, it may reflect our finding of a higher percentage of women than men reporting using cannabis for medical purposes and a lower percentage of women than men reporting using cannabis for recreational purposes.

The present study provides new insights into sex differences in the methods used to administer cannabis. Specifically, men were more likely than women to report primarily smoking joints/blunts and using concentrates and vaporizers, whereas women are more likely than men to report primarily using pipes and oral methods of administration (edibles, tinctures, capsules). Joints/blunts and some concentrates require more skill to prepare, while pipes, and oral ingestion are easier and more discrete methods. As such, sex differences in methods of administration may reflect women's tendency to be less experienced and/or more discrete about their cannabis use.

Findings from the present study also revealed a number of sex differences in the acute effects of cannabis intoxication. Somewhat surprisingly, men were more likely than women to report memory improvement when high. This result is contradictory to previous controlled laboratory research that indicates that an acute dose of sublingually administered THC improves the spatial working memory performance of female, but not male, cannabis users.⁴² Therefore, it is possible that our effect is biased by the self-report nature of our survey. In other words, men may simply be more likely to perceive and report these experiences than women. Similarly, previous research suggests that cannabis users may be more susceptible to false memories/memory distortions,⁵⁰ leaving open the possibility that part of the experienced improvement involves the recall of false, rather than veridical, memories. To our knowledge no research has examined potential sex differences in false memories of cannabis users, but such research may prove to be enlightening. Further, our study did not distinguish between the many different types of memory (e.g., implicit, explicit, verbal, spatial) and as such future research should include more fine-grained analyses into the various types of memory impairments and improvements that men and women report experiencing when under the influence of cannabis.

Men in the present study were also significantly more likely to report experiencing altered time perception, increased musicality, and enthusiasm when high. These findings are also novel and somewhat surprising. While it is known that acute cannabis intoxication alters time perception,⁵¹ to our knowledge, sex differences in this effect have not been previously discovered. Future research employing time estimation tasks is needed to examine this effect objectively. Finally, our finding that women were more likely than men to report a desire to clean likely reflects the fact that women are more likely to be responsible for cleaning duties. It is also possible that some women interpreted this item to include personal cleaning and self-care, which in general women are also likely to perform more frequently.

It is widely known that acute cannabis intoxication results in increased appetite. Our results further reveal that a larger percentage of men than women reported increased appetite, while a larger percentage of women than men reported decreased appetite when high. These sex differences are consistent with the results of animal research showing that a cannabinoid agonist increased the consumption of sweetened condensed milk in male rats in the first, second, and third hour post-injection, while it only increased consumption in the female rats in the third hour post-injection.⁵² Similar sex differences in cannabinoid-induced hyperphagia have been reported in guinea pigs.⁵³ Finally, these findings are consistent with research showing that an acute dose of the cannabinoid agonist dronabinol resulted in a higher fasting gastric volume (associated with reduced satiation) in men and slowed gastric emptying (associated with decreased appetite) in women.⁵⁴ Future research may consider examining the types of cravings (e.g., sweets, carbohydrates) that cannabis users experience and whether they vary as a function of sex.

Sex differences in the specific withdrawal symptoms reported by men and women were also detected. For instance, men were more likely than women to report experiencing sleep disturbances and vivid dreams during withdrawal. This result is consistent with previous research showing that men abstaining from cannabis spend less time sleeping and less time in rapid eye movement (REM) sleep than women abstaining from cannabis.⁵⁵ Dream intensity increases with REM deprivation⁵⁶; therefore, men's more frequently experience of vivid dreams may be a function of their decreased time in REM sleep during withdrawal.

Our findings indicate that women are more likely than men to report experiencing nausea and anxiety during withdrawal. Consistent with these effects female medical cannabis users were more likely than male medical cannabis users to report using cannabis to treat nausea and anxiety. However no sex differences in the perceived efficacy of cannabis in treating nausea or anxiety were detected. Likewise, female medical cannabis users were more likely than male medical cannabis users to report using cannabis to treat anorexia, IBS, and headaches/migraines. However, no sex differences in the perceived efficacy of cannabis in treating anorexia or IBS were detected, and men reported that cannabis is more effective in treating headaches/migraines. These patterns of results likely reflect women's higher base rates and increased susceptibility to experience and report nausea,^57–59 anxiety,⁶⁰ anorexia,⁶⁰ IBS,⁶¹ and headaches/migraines^62–64 rather than cannabis-specific effects.

As with most survey studies, the present study is limited by potential bias in self-reports, including but not limited to, exaggeration of beneficial effects, diminishment of negative effects, recall bias, and in the case of the medical data potential placebo effects. An additional limitation concerns our findings of sex differences in frequency, quantity, and method of use and the impact that these differences may have on our findings of acute and withdrawal effects. It is possible that men's increased frequency and quantity of use and their preference for different routes of administration may be impacting or driving some of the sex differences in the acute and withdrawal effects. For instance, it is possible that we did not replicate previous findings of increased withdrawal symptoms in women^32,33 because of their lower frequency and quantity of use. Future more controlled research will need to examine these possibilities and further validate our results.

While our findings provide intriguing insights into sex differences in the use and effects of cannabis, caution should be taken when generalizing results from this self-selected convenience sample to the general population. Our exclusion of individuals who had not used cannabis in the past 90 days was practical and ensured that the survey questions would be relevant to participants; however, it limits the generalization of our findings to recent cannabis users. The sample was also predominantly Caucasian and lacked ethnic diversity. It is possible that individuals from minority groups, who are more likely to be arrested for cannabis-related offenses,^65,66 were more hesitant to participate. While individuals from a variety of different countries and regions completed the survey, the origin of the survey was Washington State, and the majority of participants were from this state. Regional differences in the availability of different forms of cannabis and in medical cannabis laws may have therefore affected some of the outcomes. Despite our use of a convenience sample of predominantly Caucasian, recent cannabis users residing in Washington State, our sample was very large and well balanced with respect to sex, which increases our confidence in the generalizability of the present findings to this specific population of cannabis users.

These results can be used to guide future research on biological and psychosocial mechanisms underlying cannabis-related sex differences and to inform clinicians treating individuals with cannabis use disorders. Our findings indicate that men attempting to quit cannabis may benefit from sleep aids, while women may benefit from anti-emetics and training in anxiety coping strategies. Finally, the results should be used to inform the growing population of cannabis consumers, policymakers, and medical cannabis service providers, about some of the risks and benefits of cannabis for both sexes so they can make more informed decisions about the use and regulation of cannabis.