CRx MAGAZINE

Summer 2020

Cannabis and Sex

Does it help, does it hurt, or is it a mixed bag?

The internet is rife with anecdotal reports that cannabis use improves sexual experience. According to users, it can boost libido, arousal, and orgasm, among other benefits. But how much data are there to support these benefits?

Unfortunately, research on how cannabis affects sexual function is limited, and the studies that exist are generally poor quality. “A lot of them are observational. There haven’t been large prospective studies looking at the effects of cannabis or THC on sexual function or dysfunction,” says Saneal Rajanahally, MD, a private practice urologist in Atlanta who specializes in men’s health, male reproductive medicine, and surgery.

Still, the existing research gives reason to believe cannabis does in fact influence sexual function—both positively and negatively. Survey data consistently suggest that using cannabis has a beneficial impact on libido, sexual pleasure, and orgasm in both sexes. On the negative side, it’s also been linked with increased erectile dysfunction in men. Here, CRx breaks down the existing research and identifies the questions that remain to be answered.

The Theoretical Basis for a Connection Between Cannabis and Sexual Function
There are several ways cannabis could influence sexual experience. For one, the cannabinoids found in cannabis (such as THC) can have a direct impact on sexual function by acting on the body’s cannabinoid receptors in ways that affect the release of sexual hormones. Cannabinoid receptors are densely expressed in the hypothalamic-pituitary axis, which is known to modulate sexual function.1 The activation of cannabinoid receptors in this area inhibits the release of hormones from the hypothalamus, which may in turn influence the release of sex hormones from the sexual organs. In men, clinical research hasn’t shown a consistent effect of cannabis on testosterone levels, but animal and in vitro studies suggest a potential negative effect.2 In women, it’s known that cannabis (in particular, THC) causes a decrease in release of estrogen from the ovaries and a decrease in the release of progesterone from corpus luteum.3

Not only are cannabinoid receptors found in brain regions implicated in sexual function, they’re also found on the sexual organs themselves, including the adrenals and the ovaries.3 In men, activation of the cannabinoid receptors on erectile tissue is known to influence blood flow to the penis, which could affect the ability to achieve and maintain an erection.2

Although cannabis could have direct effects on sexual function via the above mechanisms, it could also influence sexual behavior and experience through indirect mechanisms, such as by interfering with release of neurotransmitters.1,3 The CB1 receptor (one of the two main types of cannabinoid receptors in the human body) is a presynaptic receptor, and its activation inhibits production of a number of neurotransmitters that are key to sexual function, including dopamine and serotonin.3 By interfering with neurotransmitter release, cannabis can influence processes such as desire, arousal, and anxiety.1

Libido
A number of experiments in animals have found that THC improves sexual receptivity, sexual proceptivity (that is, solicitation of a male), and sexual motivation in female rodents.4-6 Some of the cannabinoids that are naturally produced by the body (called endocannabinoids) have been shown to have similar effects.7 By contrast, cannabinoid antagonists—that is, molecules that block the activation of cannabinoid receptors—inhibit these sexual behaviors in females.6-8

However, the research in animals isn’t consistent, as several studies in rodents have found that various cannabinoids can sometimes decrease sexual receptivity, proceptivity, and motivation, and that cannabinoid antagonists can sometimes increase the same behaviors. The discrepancies in the findings from animal models may result from the different types of animals used, the variation in the cannabinoids and cannabinoid antagonists studied, and the different ways that researchers have measured receptivity, proceptivity, and motivation across studies.3

In addition to animal models, an array of clinical studies have examined the possible connection between cannabis and libido in humans. These studies are almost all based on survey data and are therefore vulnerable to bias, but the existing data suggest that cannabis is associated with an increase in libido.

In the 1970s, several surveys of cannabis users found cannabis was associated with an increase in sexual desire.9-11 All of these studies found that the effect appeared to be dose dependent: Moderate use was associate with a benefit, but the benefit disappeared with greater usage. More recently, several other studies have confirmed an effect of cannabis on libido.12 A 2019 survey of 373 women found that the majority reported increases in sex drive associated with using marijuana.13 And a 2019 survey of 112 cannabis users (both men and women) similarly found that 58.9% said cannabis increased their desire for sex.14

While most survey data suggest a benefit of cannabis for libido, two studies deserve mention for the fact that their findings run against this trend. The first is a study from researchers at the University of British Columbia that’s one of the only clinical studies of cannabinoids and sex that has employed an objective measurement of sexual function (rather than survey data). In the study, the researchers measured endocannabinoid concentrations of 21 women just before and just after watching both neutral and erotic films. During the films, they also measured the women’s vaginal pulse amplitude, which is a signal of genital engorgement and is a proxy for sexual arousal in women. They found that sexual arousal, as determined by both vaginal pulse amplitude and subjective report, was linked to a decrease in levels of endocannabinoids—a finding that suggests that the endocannabinoid system may inhibit arousal.15

The other study is a 2004 survey from researchers at New York University that was designed to examine a possible link between cannabis use and sexual dysfunction. This survey, which included slightly more than 3,000 participants, found that use of marijuana was associated with reduced sexual excitement and desire, even after controlling for multiple variables.16

Sexual Pleasure and Satisfaction
A number of surveys in the 1970s and ’80s found that cannabis use is linked to greater sexual pleasure.9,10,17,18 In a survey conducted by the US Commission on Marihuana and Drug Abuse, about 70% of those who used cannabis frequently (but short of daily) said their use increased their sexual pleasure9; in other surveys, the percentage of those reporting a cannabis-associated increase in pleasure was even higher.17,18 Some of this research also found that cannabis users reported an increased sense of satisfaction with sex and a greater sense of emotional closeness and intimacy with their partner.17

More recently, a survey of 679 young adults compared the effects of marijuana, alcohol, and ecstasy on sexual experience. Among those who had used marijuana, the majority reported that it increased their sexual enjoyment, and substantial percentages also reported that it increased their sexual intensity and their body sensitivity.19 Likewise, a Canadian survey of 216 participants (all of whom had used cannabis with sex) found that 73.8% reported an increase in sexual satisfaction. In the Canadian study, the majority of participants also said that using cannabis with sex improved their sensitivity to touch (74.3%), ability to relax (69.8%), and ability to focus (50.5%).14

Thus, most available evidence suggests that marijuana has positive effects on sexual pleasure and satisfaction. As with its effects on sexual desire, the impact is likely dose dependent: Moderate use appears to have a beneficial impact on pleasure, but too frequent use is linked to reduced pleasure.9,10

Orgasm
As with libido and sexual pleasure, most research indicates that cannabis use is associated with enhanced orgasms. This link has been found among both men and women, among surveys from the 1970s and ’80s as well as in more recent surveys.13,14,17-19 That said, the New York University study of sexual dysfunction mentioned earlier found that frequent marijuana use was associated with inhibited orgasm in both genders as well as premature ejaculation in men.16 In addition, an Australian study of more than 8,656 adults (754 of whom were cannabis users) found that frequent use of cannabis wasn’t associated with sexual dysfunctions in women, but it was linked in men to an inability to reach orgasm, reaching orgasm too quickly, or reaching orgasm too slowly.20

Erectile Dysfunction
There’s some evidence from in vitro, animal, and human studies that cannabis use may diminish erectile function. This is due in part to the effects of cannabis in the brain and in part to its local effects on the penis.

As for the impact of cannabis on the brain, one important brain area known to modulate erectile function is the paraventricular nucleus of the hypothalamus. The paraventricular nucleus contains CB1 cannabinoid receptors (which are activated by THC), and animal models have found that injecting these receptors with molecules that block their activation can artificially induce an erection.2 In other words, blocking activation of cannabinoid receptors “may actually improve erectile function,” Rajanahally says. “That would suggest from a brain standpoint, that potentially cannabis would actually have an inhibitory effect on erectile function.”

There’s also concern about the local effects of cannabis on the nerve fibers of the penis. Achieving an erection requires relaxation of smooth muscle tissue in the penis, and there are cannabinoid receptors on the nerve fibers in the penis that influence this relaxation. However, activation of these receptors appears to have different effects in different species. In rodent models, endocannabinoids promote relaxation of erectile tissue, thus increasing erectile function. But in primates, the opposite occurs—endocannabinoids inhibit relaxation.2

The relaxation of penile tissue in turn affects blood flow to the penis. To achieve an erection, Rajanahally says, “you need to have dilation of the arteries that supply blood into the penis and compression of the veins which are responsible for blood leaving the penis. A problem with either aspect may result in diminished erectile function.” Some research suggests that cannabis use impedes endothelial function and thus interferes with the dilation and compression necessary to achieve an erection.21

That said, survey results have been inconsistent regarding an association between cannabis use and erectile dysfunction. One study found that daily marijuana users had close to twice the rate of erectile dysfunction than that of those who didn’t use cannabis.22 But in the New York University Study of sexual dysfunction—which had 4,350 male participants—there was no link between frequent cannabis use and difficulty sustaining an erection.16 In other words, Rajanahally says, “there may be a disconnect between what we see in the basic science laboratory or animal models and clinically what people are experiencing.”

Takeaways for Clinicians
It’s impossible to draw firm conclusions about the effects of cannabis on sex given that so much of the data is survey data. “There’s a lot of room for bias with [surveys],” says Becky Lynn, MD, director of the Evora Center for Sexual Health in Chesterfield, Missouri, and an adjunct associate professor of obstetrics and gynecology at Saint Louis University. “[They’re] based on people’s recall. There’s no way to measure how much marijuana they used, or the timing—did they smoke it six hours before and then have sex; did they eat it and then have sex four hours later? There are just so many variables that aren’t controlled.”

Still, she says, most surveys do seem to suggest that moderate cannabis use increases sexual desire, increases sexual pleasure, and improves orgasms for both men and women. “My gut feeling is there are probably benefits when used in the right environment,” Lynn says.

According to Ellen Wiebe, MD, a clinical professor of medicine in the University of British Columbia Department of Family Practice, these benefits of cannabis probably don’t come through any direct effect on the sexual organs or the production of sex hormones; rather, they come via cannabis’s impact on relaxation, focus, and sensitivity.

Though there are likely some benefits of cannabis for sex, all other sources consulted for this article say the effects likely depend on dosage. “For many people at the right dose, it is relaxing. If people are tense and are able to relax, then they are able to function better sexually,” Wiebe says. But in her research, “at higher doses, people got sleepy and totally uninterested in sex.”

The experts shared the following tips for advising patients regarding cannabis and sex:

Be clear about the uncertainties surrounding cannabis. “Make sure the patient understands that the evidence out there in terms of marijuana and sexual health is very mixed; it’s very confusing,” Rajanahally says. In addition to the uncertainties about the effects on sexual function, there are also lingering questions about the long-term safety of regular cannabis use.

Be wary about recommending cannabis to improve sexual function. In many states where cannabis is legal for medical purposes but not recreational purposes, such as Lynn’s state of Missouri, there’s ambiguity about the legality of recommending for sexual function. “It’s a very gray zone whether anything sexual counts as a medical condition warranting the use of marijuana,” she says.

But even if it is within the law to do so, Rajanahally says the evidence isn’t strong enough yet to warrant recommending cannabis for the purpose of boosting sexual function. Instead of recommending cannabis, he encourages physicians to simply advise patients who are already users about the effects they’re likely to see. He wouldn’t recommend cannabis to increase libido. “I would say if a patient is on marijuana for some other medically indicated reason, he may experience a subjective increase in libido.”

Lynn agrees about the need for caution, suggesting that clinicians need to consider other factors before assuming cannabis would provide a benefit for their patients. “You have to do a complete [biopsychosocial] assessment,” she says. “How’s your relationship with your partner? Are you depressed? Are you on antidepressants that cause low libido? You have to look at the whole picture, and then [cannabis] might be one small piece of the puzzle, in the right person, in the right environment.”

For male cannabis users experiencing erectile dysfunction, consider advising them to reduce their cannabis intake. According to Rajanahally, current evidence isn’t conclusive, but it’s possible that cannabis could have beneficial neuronal effects in the brain (enhancing sex drive, pleasure, and orgasm) while having a simultaneous negative local response in penile tissue (contributing to erectile dysfunction).

Finally, consider whether patients are interested in having children, since cannabis use likely harms fertility. “Marijuana consumption in males seems to be higher in the age groups of 20s to 40s vs elderly men in general,” Rajanahally says. “These are the same men that are often trying to have children, and the majority of the data out there does suggest that it has negative effects on semen parameters and your sperm.”

— Jamie Santa Cruz is a health and medical writer in the greater Denver area.

References

1. Klein C, Hill MN, Chang SC, Hillard CJ, Gorzalka BB. Circulating endocannabinoid concentrations and sexual arousal in women. J Sex Med. 2012;9(6):1588‐1601.

2. Rajanahally S, Raheem O, Rogers M, et al. The relationship between cannabis and male infertility, sexual health, and neoplasm: a systematic review. Andrology. 2019;7(2):139‐147.

3. Lynn B, Gee A, Zhang L, Pfaus JG. Effects of cannabinoids on female sexual function. Sex Med Rev. 2020;8(1):18-27.

4. Gordon JH, Bromley BL, Gorski RA, Zimmermann E. Delta9-Tetrahydrocannabinol enhancement of lordosis behavior in estrogen treated female rats. Pharmacol Biochem Behav. 1978;8(5):603-608.

5. Turley WA Jr, Floody OR. Delta-9-Tetrahydrocannabinol stimulates receptive and proceptive sexual behaviors in female hamsters. Pharmacol Biochem Behav. 1981;14(5):745-747.

6. Mani SK, Mitchell A, O’Malley BW. Progesterone receptor and dopamine receptors are required in delta 9-tetrahydrocannabinol modulation of sexual receptivity in female rats. Proc Natl Acad Sci U S A. 2001;98(3):1249‐1254.

7. Memos NK, Vela R, Tabone C, Guarraci FA. Endocannabinoid influence on partner preference in female rats. Pharmacol Biochem Behav. 2014;124:380-388.

8. Zavatti M, Carnevale G, Benelli A, Zanoli P. Effects of the cannabinoid antagonist SR 141716 on sexual and motor behaviour in receptive female rats. Clin Exp Pharmacol Physiol. 2011;38(11):771‐775.

9. US Commission on Marihuana and Drug Abuse. Marihuana: a signal of misunderstanding: appendix. Schaffer Library of Drug Policy website. http://www.druglibrary.org/schaffer/Library/studies/nc/ncmenu.htm. Published 1972.

10. Koff WC. Marijuana and sexual activity. J Sex Res. 1974;10(3):194‐204.

11. Chopra GS, Jandu BS. Psychoclinical effects of long-term marijuana use in 275 Indian chronic users. A comparative assessment of effects in Indian and USA users. Ann N Y Acad Sci. 1976;282:95‐108.

12. Green B, Kavanagh D, Young R. Being stoned: a review of self-reported cannabis effects. Drug Alcohol Rev. 2003;22(4):453‐460.

13. Lynn BK, López JD, Miller C, Thompson J, Campian EC. The relationship between marijuana use prior to sex and sexual function in women. Sex Med. 2019;7(2):192‐197.

14. Wiebe E, Just A. How cannabis alters sexual experience: a survey of men and women. J Sex Med. 2019;16(11):1758‐1762.

15. Klein C, Hill MN, Chang SC, Hillard CJ, Gorzalka BB. Circulating endocannabinoid concentrations and sexual arousal in women. J Sex Med. 2012;9(6):1588‐1601.

16. Johnson SD, Phelps DL, Cottler LB. The association of sexual dysfunction and substance use among a community epidemiological sample. Arch Sex Behav. 2004;33(1):55‐63.

17. Halikas J, Weller R, Morse C. Effects of regular marijuana use on sexual performance. J Psychoactive Drugs. 1982;14(1-2):59‐70.

18. Dawley HH Jr, Winstead DK, Baxter AS, Gay JR. An attitude survey of the effects of marijuana on sexual enjoyment. J Clin Psychol. 1979;35(1):212‐217.

19. Palamar JJ, Griffin-Tomas M, Acosta P, Ompad DC, Cleland CM. A comparison of self-reported sexual effects of alcohol, marijuana, and ecstasy in a sample of young adult nightlife attendees. Psychol Sex. 2018;9(1):54‐68.

20. Smith A, Ferris J, Simpson J, Shelley J, Pitts M, Richters J. Cannabis use and sexual health. J Sex Med. 2010;7:787-793.

21. Aversa A, Rossi F, Francomano D, et al. Early endothelial dysfunction as a marker of vasculogenic erectile dysfunction in young habitual cannabis users. Int J Impot Res. 2008;20:566-573.

22. Cohen S. Cannabis and sex: multifaceted paradoxes. J Psychoactive Drugs. 1982;14(1-2):55‐58.

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