The effects of cannabis on the hormonal system and male fertility remain controversial within the scientific community. A study conducted by the University of Geneva (UNIGE) in collaboration with the Swiss Center for Applied Human Toxicology (SCAHT) has provided a new answer, showing that cannabis use does not reduce testosterone levels in young men and may even increase testicular synthesis.
However, increased levels of this hormone are not directly related to fertility. These conclusions are based on detailed analysis of plasma samples from 94 Swiss conscripts. Additionally, researchers identified two new hormonal biomarkers that may be useful in detecting regular cannabis use. The survey results are communication medicine.
Some studies suggest that cannabis may reduce sperm count, concentration, and motility. These effects are thought to be related to the endocannabinoid system, a network of chemical messengers and receptors in the brain and reproductive organs that interact with sex hormones. However, the results of studies conducted to date, particularly regarding the effects of cannabis use on testosterone, are often contradictory.
To investigate further, a team from the Department of Pharmaceutical Sciences, Faculty of Science, UNIGE, led by Professor Serge Rudasz, in collaboration with SCAHT, carried out a detailed analysis of steroid hormones (including sex hormones such as androgens, progestogens and estrogens) in plasma samples of Swiss conscripts aged 18 to 23. This cohort included 47 confirmed cannabis users and 47 non-users. The main innovation of this study was in extending the analysis to hundreds of hormones, whereas previous studies focused only on testosterone.
increase in testosterone
Our results show that cannabis use leads to an approximately 23% increase in testosterone in young men. However, by taking a closer look at all male hormones, or androgens, we were able to pinpoint that this increase was specifically in the testes. Androgens produced by the adrenal glands were not affected by this increase. ”
Serge Rudas, Professor, Faculty of Science, University of Geneva
Therefore, cannabis appears to have a direct effect on the testes, and more specifically on the Leydig cells that produce testosterone.
Thanks to this extensive analysis, the team was also able to identify two potential new biomarkers of cannabis use: hydroxyprogesterone (11B-OHP4) and dihydroprogesterone (5B-DHP4).
“These are two metabolites derived from progesterone, another important sex hormone. The increased concentrations among users are so high that they could be used to monitor endocrine disruption associated with regular cannabis exposure. Above all, this finding This should encourage the scientific community to expand its research into new hormones that have been overlooked and may also play a role in the male reproductive system,” explains Matthew Garmisch, a former post-doctoral researcher in UNIGE’s Department of Pharmaceutical Sciences. researcher at the Karolinska Institutet in Stockholm and lead author of the study.
No relationship to sperm quality
However, elevated hormone levels in cannabis users should not be interpreted as an indicator of sperm quality. The relationship between testosterone and fertility remains very complex to decipher. Additionally, the observed increase may represent the body’s compensatory response to the decreased sensitivity of certain androgen receptors in the presence of cannabis. It’s also possible that men with naturally higher testosterone levels are more likely to engage in risk-taking behavior and, as a result, more likely to use cannabis.
Cannabis appears to affect certain biological mechanisms related to reproduction, but its precise clinical effects on fertility in young men remain unclear. Further research is needed to determine whether a toxicity threshold exists and assess potential long-term effects.
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Reference magazines:
Garmisch, M. others (2026). Cannabis consumption is associated with changes in steroid metabolism in young men. communication medicine. DOI: 10.1038/s43856-026-01469-x. https://www.nature.com/articles/s43856-026-01469-x.
