Every Friday on the blog, I answer people’s questions about sex, love, and relationships. This week’s question comes from a reader who wanted to know the following:

“Is marijuana an aphrodisiac? And can it make a guy last longer in bed?”

Good questions! If you survey people about how marijuana impacts their sex lives, many people do report that this drug has aphrodisiac-like properties. For instance, in a 2008 study of 41 recreational pot users, 44% reported that the drug has positive sexual effects, such as enhanced libido or more sensitivity to touch [1]. Given that these effects were reported by less than half of the participants, it is clear that this drug doesn’t seem to affect everyone the same way. Also, the nature of these data cannot tell us whether marijuana truly puts some people “in the mood,” or if we’re just dealing with expectancy effects here—in other words, for people who expect marijuana to enhance their sex lives, it may indeed have that effect simply because they convinced themselves that it would. Expectancy effects are actually a big part of the reason that most supposed aphrodisiacs have the reputation that they do.

As for the question of whether weed increases guys’ sexual stamina, a few survey studies have found that marijuana does indeed have this effect for a majority of male participants [2]. However, some caution is warranted in interpreting this finding, given that it is based on men’s unverified self-report data. While it certainly could be the case that marijuana gives some men longer-lasting erections, it could also be the case that this drug alters men’s perception of time, leading them to draw erroneous conclusions about how long they lasted.

In an attempt to see how marijuana actually affects the penis, biomedical researchers have begun to look at this issue more closely. This may surprise some of you, but animal studies have found that cannabis has inhibiting effects on some receptors in the penile tissue, suggesting that marijuana has the potential to decrease both quantity and quality of erections [2].

However, just like with alcohol, the dose is likely to be important. In small quantities, the inhibitory effects might be very weak, which gives way to some aphrodisiac-like effects (due to the combined influences of expectancy effects and the drug loosening people’s inhibitions). In large quantities, though, it is more likely to cause sexual problems. Consistent with this, one study found that the rate of erectile dysfunction was three times higher among daily marijuana smokers compared to non-smokers [3].

In addition to the dose, it is important to keep in mind that there are individual differences in sensitivity to the drug, which may lead it to be experienced very differently across persons (the same goes for booze--perhaps you know some people who are intoxicated after just one drink, and others who can drink a ton but never seem drunk). Likewise, some people combine marijuana use with other substances, which may produce different effects as well. And then there's also the possibility that different strains of marijuana might have different effects on the body. Together, all of this means that the research in this area is very complicated and it is difficult to draw firm conclusions.

As you can see, we are just beginning to understand the effects of marijuana on our sexual responses. Although much more research is needed (particularly, controlled clinical studies), the one thing that is clear is that this drug does not appear to have aphrodisiac effects in everyone who uses it.

For previous editions of Sex Question Friday, click here. To send in a question for a future edition, click here.

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[1] Osborne, G.B., & Fogel, C. (2008). Understanding the motivations for recreational marijuana use among Canadians. Substance Use and Misuse, 43, 539-572.

[2] Shamloul, R., & Bella, A. J. (2011). Impact of cannabis use on male sexual health. The Journal of Sexual Medicine, 8, 971-975.

[3] Cohen, S. (1982). Cannabis and sex: Multifaceted paradoxes. Journal of Psychoactive Drugs,14, 55–70.

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