With the legalization of cannabis in many states across the nation, more and more patients have started admitting the usage of this herb to their doctors. While much of the current medical literature boasts the medicinal benefits of cannabis, less press has been dedicated to the potential harm cannabis can cause to reproductive function. The bulk of the research in this area has been conducted on animals, often rhesus monkeys given injectable tetrahydrocannabinol (THC). Human studies are on the rise, providing some insight into the effects of chronic cannabis use on men’s health.
Cannabis use has been tied to lower testosterone levels in men. Human studies have shown dose-dependent decreases in luteinizing hormone and testosterone among male long-term cannabis users. THC, the primary psychoactive constituent in cannabis, blocks the release of gonadotropin-releasing hormone (GnRH), which leads to lower LH causing the Leydig cells to produce less testosterone. Both in vivo and in vitro studies have shown that cannabis disrupts spermatogenesis and sperm function – specifically motility, capacitation and acrosome reaction, the process wherein spermatozoa fuse with eggs. One study found that more than 1/3 of male chronic exclusive cannabis users tested had oligospermia.
THC has been shown to depress prolactin, thyroid function and growth hormone, and to elevate adrenal cortical steroids in animals. Animal studies have also shown that THC and other cannabinoids can acutely suppress gonadal steroids, growth hormone, prolactin, and TSH. Human studies have shown inconsistent effects likely due to tolerance, meaning that with long-term use, the hormone changes seen initially may change.
Additionally, the cannabinoids in cannabis disrupt the function of the natural endocannabinoids that play a role in regulating the reproductive system. Endocannabinoid receptors are found on human testes and sperm. In the human body, endocannabinoids are released and removed rapidly. In contrast, THC has a long half-life of 24 to 36 hours and is fat-soluble, which could cause overstimulation of the endocannabinoid system. This may partially explain the mechanism by which exogenous cannabinoids disrupt the reproductive system.
More scientific studies are needed in order to fully understand the relationship between cannabis and human hormone balance. In the meantime, patients that regularly use cannabis – whether recreationally or medicinally – can benefit from monitoring their hormone levels. A Comprehensive Hormone Profile is an excellent way to begin to serve this population.