For years, scientists have debated how cannabis affects male reproductive health.
As cannabis use becomes more common in many countries, questions about its long-term effects on hormones and fertility have become increasingly important.
Some studies have suggested that cannabis may harm sperm quality and lower testosterone levels, while others have found little evidence of these effects. Because of these conflicting findings, researchers have continued searching for clearer answers.
Now, a new study from the University of Geneva (UNIGE) in Switzerland offers a surprising perspective. The research suggests that cannabis use among young men does not lower testosterone levels. In fact, it may actually increase the production of testosterone in the testes. The findings were published in the journal Communications Medicine.
The study was carried out by researchers from the University of Geneva in collaboration with the Swiss Center for Applied Human Toxicology. Their goal was to better understand how cannabis affects the body’s hormonal system, particularly hormones involved in male reproduction.
Male fertility is influenced by many factors, including hormone levels, sperm production, lifestyle habits, age, and overall health. Testosterone is one of the most important male sex hormones.
It plays a major role in sexual development, muscle growth, bone health, and reproductive function. Because testosterone is so important, scientists have long wondered whether cannabis use changes its levels.
Previous studies have produced mixed results. Some researchers reported that cannabis users had lower sperm counts, reduced sperm movement, and poorer sperm quality. Others found little evidence that cannabis directly affects reproductive hormones. One reason for these disagreements may be that earlier studies often focused on only one hormone at a time.
The Swiss research team took a broader approach. They analyzed blood samples from 94 Swiss military conscripts between the ages of 18 and 23. The group included 47 confirmed cannabis users and 47 non-users. Instead of looking only at testosterone, the researchers measured hundreds of steroid hormones and hormone-related compounds circulating in the blood.
This wider analysis allowed the team to gain a much more detailed picture of how cannabis influences the endocrine system, which is the network of glands and hormones that regulate many body functions.
The results showed that cannabis users had testosterone levels that were about 23 percent higher than those of non-users. When researchers examined related hormones, they found that the increase appeared to come specifically from the testes. Hormones produced by the adrenal glands, another source of androgens in the body, did not show the same pattern.
According to the researchers, this suggests that cannabis may directly affect Leydig cells, the specialized cells inside the testes that produce testosterone.
The study also uncovered two hormone-related substances that may serve as new biological markers of regular cannabis use. These compounds, called hydroxyprogesterone and dihydroprogesterone, are produced from progesterone, another hormone involved in reproductive health. Their levels were significantly higher among cannabis users.
Researchers believe these substances could eventually help scientists better understand how cannabis affects the hormonal system. They may also help identify people who are regularly exposed to cannabis and allow researchers to monitor hormone-related changes over time.
However, the findings do not mean that cannabis improves fertility. The researchers emphasize that higher testosterone levels should not automatically be interpreted as a sign of better reproductive health.
The relationship between testosterone and fertility is much more complicated than many people realize. Fertility depends on sperm production, sperm quality, sperm movement, hormone balance, and many other biological processes. A rise in testosterone alone does not guarantee improved fertility.
The researchers also suggest several possible explanations for the increase in testosterone. One possibility is that the body may be compensating for reduced sensitivity of certain hormone receptors caused by cannabis exposure.
Another possibility is that young men who naturally have higher testosterone levels may be more likely to engage in risk-taking behaviors, including cannabis use.
Because this study was observational, it cannot prove that cannabis directly caused the increase in testosterone. It can only show that the two were associated in this group of participants.
The study’s greatest strength is its detailed analysis of hundreds of hormones rather than focusing on a single measurement. This provides a more complete understanding of how cannabis may influence the endocrine system.
However, the study also has limitations. The sample size was relatively small, and all participants were young Swiss men. The results may not apply to older adults or people from different populations.
Overall, the findings challenge the common belief that cannabis automatically lowers testosterone levels. At the same time, they highlight how much remains unknown about cannabis and male fertility.
More long-term studies will be needed to determine whether there is a level of cannabis exposure that becomes harmful and whether the hormonal changes observed have any meaningful impact on reproductive health.
The study was published in Communications Medicine.
Source: University of Geneva.
