Does Marijuana Use Affect Sperm?

Any updated information on pot and sperm counts?
—Anonymous

There is continual speculation that marijuana consumption could lower sperm counts or, more generally, impact sperm. It’s not just the number of sperm you have that is relevant. It’s the quality — their shape, how good they are at swimming, etc. There are lots of things that affect sperm. Tight underwear, for example.

In mice, marijuana exposure is linked to infertility. There are biological reasons to think the link might be in people too. There is a 2021 review that pulls together what we know about marijuana consumption and sperm parameters. It does conclude that marijuana is linked to lower sperm counts and worse sperm quality.

However: the evidence is limited. Part of the problem is that sperm quality evaluation isn’t something that people typically do for fun; it usually happens as a result of an evaluation for subfertility or infertility. What the data can show is evidence of a correlation between pot and sperm among a set of people who are experiencing infertility. It’s not clear that this applies in general.

In principle, one could imagine doing an evaluation of this question in healthy men, especially since sperm gets regenerated over time. You could take a cohort of regular marijuana users and encourage a “treatment group” to abstain for a certain period, and measure sperm over time. I am not aware of any studies that have done that. What we can say for now is that the link seems possible and, if you’re struggling with male infertility, it is worth evaluating.