May 31, 2011
Men who use marijuana may be more likely to have erectile dysfunction (ED), according to research published in the January 26, 2011 online edition of The Journal of Sexual Medicine.
Rany Shamloul, a postdoctoral fellow at Queen’s University in Canada, conducted a literature review to learn more about how marijuana affects a man’s sexual health in the short term.
Erectile dysfunction is a man’s inability to achieve an erection suitable for satisfying sex.
The link between marijuana and ED involves tetrahydrocannabinol (THC), the active ingredient in marijuana.
Studies have shown how THC affects the brain. When a person smokes marijuana, THC gets into the bloodstream and travels to the brain and other organs.
When THC reaches the brain, it interacts with proteins called cannabinoid receptors. This interaction triggers cellular reactions that make a person feel “high” and interfere with normal functioning.
It appears that THC might affect the penis the same way.
In his research, Dr. Shamloul examined a 2010 study in the journal European Urology. This study reported that there were cannabinoid receptors in the penises of five men and six rhesus monkeys. Most of the receptors were found in the smooth muscle of the penis. It appeared that THC impaired the smooth muscle’s normal function.
This finding suggests that marijuana use could affect a man’s ability to have an erection, since the human penis is 70% to 80% smooth muscle.
The results could have implications for women as well.
“The erectile tissue in the penis is similar to the tissue in the clitoris in that they both have cannabinoid receptors, so cannabis use could, in theory, affect a female’s ability to become sexually aroused as well,” Dr. Shamloul told The Queen’s Journal, the student newspaper of Queen’s University.
In spite of these findings, studies on marijuana and sexual function have had mixed results overall. Some studies show positive results; others are negative. Also, Dr. Shamloul noted that additional research would be helpful, especially to see how marijuana use affects sexual health in the long term.
“What we are really missing are clinical studies,” he told LiveScience. “We are stuck with only animal studies and molecular studies, and some clinical studies done in the ‘60s and ‘70s, most on a very small number of men….We need well-designed, placebo-control studies examining marijuana’s effect in both the short-term and long-term.”