In short, yes — cannabis use does seem to affect the overall health of sperm.
Although more research on cannabis and sperm health is needed, it seems that using cannabis frequently can decrease the health of your sperm, making you less fertile.
Studies have suggested that cannabis use decreases sperm count.
One 2015 study looked at 1,215 young Danish people with penises aged between 18 and 28 years.
It found that regular cannabis smoking — defined as more than once a week — was associated with 28 percent lower sperm concentration and a 29 percent lower total sperm count.
Those who used cannabis more than once a week alongside other recreational substances had a 52 percent lower sperm concentration and 55 percent lower total sperm count.
However, another study, which was published in 2019, showed the opposite.
Looking at 662 penis-having folks who attended a fertility center, researchers found that people who had smoked cannabis in the past had a higher sperm concentration than those who had never smoked cannabis.
As the researchers pointed out, this contradicts most of the studies on fertility and cannabis, most of which suggest that cannabis decreases sperm count.
However, this study had a relatively small sample size. It was also biased from the general population as it included people who went to a fertility center.
It also relied on self-reporting. It’s possible that some lied about their cannabis usage.
What this suggests is that we need to study cannabis and sperm count further.