Cannabis (also called marijuana) has the highest use in the United States compared with all other illicit substances. A large study showed 20% of men in from ages 26 to 34, and 11% of men ages 35-49 had reported using cannabis in the previous year. Given that men in their prime reproductive years are common users of cannabis, it’s important to understand the implications for reproductive health.
The active ingredient of cannabis is THC. THC has been shown to impact the hormone pathway that’s involved in testosterone (T) production. Some studies have shown that higher amounts of THC consumption is associated with a greater decrease in T levels. Manifestations of this process in chronic cannabis users include decreased sex drive, problems getting or maintaining an erection, decreased ejaculate volume or difficulty reaching orgasm in the first place, and gynecomastia (or increased breast tissue).
Within the testicles, where the majority of T is made, THC can interfere with the sperm production process. More than a third of chronic cannabis users have been shown to have a low sperm count (a condition called oligospermia). In addition to having a negative impact on sperm production, there is also evidence that THC can decrease the ability of sperm to join with an egg. Other studies have shown that heavy cannabis use can decrease sperm motility (ability to swim).
Younger men in peak reproductive years commonly use cannabis. Men who are interested in conceiving should be aware that cannabis use can impact their sperm concentration, motility, and - even if a sperm makes it all the way to an egg - the likelihood that fertilization will occur. Men who consume cannabis and want to conceive should therefore reduce or discontinue their consumption, at least until their partner is pregnant.
