New research suggests that cannabis use doesn’t reduce testosterone in young men — and may actually be linked to higher levels.
A team from the University of Geneva, working alongside the Swiss Centre for Applied Human Toxicology in Basel, investigated how cannabis might affect fertility-related markers in young Swiss men aged 18 to 23.
Their conclusions, published in Communications Medicine, ran counter to what many people might assume.
According to the university, the researchers evaluated blood samples from 94 Swiss recruits in the 18–23 age range.
The participants were divided evenly into two groups: 47 men who used cannabis and 47 who did not. The cannabis-using group showed notably higher testosterone measurements than the non-users.
Speaking to USA & World Report News, senior researcher Serge Rudaz, a professor at the University of Geneva said: “Our results show that cannabis use would lead to an increase of about 23% in testosterone in young men.”
The authors note that these findings align with earlier large-population studies in Denmark and the US, which also reported an association between cannabis use and increased testosterone. That pattern contrasts with some older, smaller studies that had suggested the reverse.
The researchers add that the observed rise seems to be driven by testosterone production in the testicles, rather than by the adrenal glands, which also produce androgens. They suggest cannabis may act directly on Leydig cells — the cells in the testicles responsible for making testosterone — while not appearing to alter adrenal hormone output.
The paper also outlines a couple of possible reasons for the association.
One idea is that the body may increase testosterone as a compensatory response if certain hormone receptors become less sensitive. Another possibility is that men who naturally have higher testosterone may be more inclined toward risk-taking behaviours, which could include cannabis use.
Even with the headline increase, the researchers cautioned against treating higher testosterone as an automatic positive.
They stressed that elevated testosterone on its own doesn’t necessarily mean healthier sperm or improved fertility, since reproductive health depends on multiple interacting factors.
Although cannabis appears to affect biological pathways related to reproduction, the researchers said the real-world, clinical implications for fertility in young men are still uncertain.
They concluded that additional studies are needed, particularly to understand any longer-term effects.