For many years, the story sounded simple: cannabis lowers testosterone in men. That idea came from early research, including a small study from 1974 that looked at only 20 men.

The message stuck, even though later studies did not always agree with it. Now, new research suggests the truth is more complicated.

A Swiss research team studied young men and measured 70 steroid hormones at once. This gave them a much wider view of the male hormone system than older studies had.

The results challenge the old belief that cannabis simply reduces testosterone.

Instead, the study found that cannabis users had higher levels of some key male hormones, while other hormone pathways stayed mostly unchanged.

For decades, researchers focused mainly on testosterone. That made the picture too narrow.

Some studies found lower testosterone in cannabis users. Others found no change. A few larger recent studies even found higher testosterone in users.

This confusion may have happened because testosterone is only one part of a much bigger hormone network. Looking at one hormone cannot explain the whole system.

The Swiss team studied 94 young men between 18 and 23 years old. There were 47 confirmed cannabis users and 47 matched non-users.

The researchers did not rely only on what participants said. They tested blood samples for THC and THC-COOH, which showed who had recently used cannabis.

They then measured 70 steroid hormones using a highly sensitive lab method called liquid chromatography tandem mass spectrometry.

This helped them see where cannabis might be affecting the hormone system.

The study found that cannabis users had significantly higher testosterone levels than non-users. On average, testosterone was about 23% higher.

The users also had higher levels of androstenedione, a hormone that helps the body make testosterone.

“Our results show that cannabis use would lead to an increase of about 23% in testosterone in young men,” said Professor Serge Rudaz, who led the study at the UNIGE Faculty of Science.

“But by taking a closer look at all male sex hormones – the androgens – we were able to locate the source of this increase specifically in the testes. Androgens produced by the adrenal glands were not affected by this increase.”

This is important because it suggests the change may come from the testes, not from the whole hormone system.

The researchers also found higher levels of DHT, short for dihydrotestosterone.

DHT is a strong male sex hormone. It can have a bigger effect on the body than testosterone because it binds more strongly to hormone receptors.

Since testosterone, androstenedione, and DHT all increased together, the researchers believe cannabis may be affecting hormone production in the testes.

The body also makes some androgens in the adrenal glands, which sit above the kidneys.

If cannabis were raising all male hormones across the body, these adrenal hormones would likely rise too. But they did not.

The adrenal androgens measured in the study showed no major difference between cannabis users and non-users. This helped researchers narrow the effect to the testes.

One possible explanation involves Leydig cells. These are cells in the testes that make testosterone. They also have cannabinoid receptors, which can interact with compounds from cannabis.

Among all 70 hormones, two unexpected compounds showed the strongest changes.

Both came from progesterone, a hormone often linked with female-reproductive health but also present in men.

The two compounds were 5beta dihydroprogesterone and 11beta hydroxyprogesterone. Both were much higher in cannabis users.

Scientists do not yet know exactly what these two hormones do in adult men. But the strong link with cannabis use makes them important to study.

“These are two metabolites derived from progesterone, another important sex hormone,” said Mathieu Galmiche, the study’s first author and a former postdoctoral researcher at UNIGE.

“The increase in their concentration among users is so high that they could be used to monitor endocrine disruptions linked to regular cannabis exposure.”

“Above all, this discovery should encourage the scientific community to expand studies to new hormones that have so far been overlooked, and which may also play a role in the male reproductive system.”

The two compounds may tell researchers different things. 11beta hydroxyprogesterone seemed to show cannabis exposure in general. It was higher in users but did not rise much more in frequent users.

5beta dihydroprogesterone looked more closely linked to how much cannabis someone used. It was higher in chronic users and rose with THC levels in the blood.

The researchers also looked at the hormone pathway that connects the brain and testes. This system helps control testosterone production.

Two important hormones in this pathway are luteinizing hormone and follicle-stimulating hormone. In this study, neither changed much between users and non-users.

That does not fully rule out brain involvement. These hormones rise and fall in pulses, so one blood sample may miss important changes.

For now, the strongest clue still points to a direct effect in the testes.

Higher testosterone may sound like good news, but the study does not prove that cannabis improves male fertility.

Hormones and fertility do not have a simple relationship. Semen quality, sperm movement, sperm count, and sperm function all matter too.

The changes in progesterone-related hormones may be important because progesterone helps sperm during fertilization.

But researchers still do not know whether these hormone changes affect fertility in real life.

This study changes the question scientists need to ask.

Instead of asking only whether cannabis lowers testosterone, researchers can now ask where cannabis affects the hormone system and which pathways change.

The answer from this study is not simple. Cannabis users showed higher testicular androgens, unchanged adrenal androgens, and strong changes in two progesterone-related compounds.

That does not settle the debate. But it does show that the old story was too simple.

Cannabis does not appear to affect male hormones in just one direction. It seems to leave a more specific and measurable pattern, one that scientists are only now beginning to understand.

The study is published in the journal Communications Medicine.

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