Research suggests that THC may temporarily lower testosterone levels after acute use, but chronic use does not appear to have a significant clinical effect.
Some studies show higher testosterone levels in recent marijuana users, which is controversial.
The evidence is mixed, and a systematic review found no clinically significant association between THC and testosterone levels.

Tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana, is the subject of numerous studies due to its potential health effects, including on testosterone levels—a key male hormone responsible for reproductive health, muscle mass, and libido. Does THC lower testosterone levels? The answer is not straightforward, as studies yield conflicting results and the topic is highly debated. In this article, we will examine the available evidence, considering both potential reductions and no effects, and provide recommendations for those interested in this topic.

What does science say?

Research on the effects of THC on testosterone levels is complex and often depends on the method of use (acute vs. chronic), dosage, and individual differences. Here's what you need to know:

Acute use and temporary decline: Some studies, such as an analysis of data from the 1980s, indicate that after smoking a single joint or administering THC intravenously, testosterone levels can temporarily drop, returning to normal after at least 24 hours.
Chronic use and no clinical impact: A 2021 systematic review published in Andrology found no clinically significant association between cannabis use and testosterone levels, suggesting that long-term use may not have a significant effect.
Unexpected discovery – higher levels in recent users: Some studies, including those based on NHANES data, have found that men who recently used marijuana had slightly higher testosterone levels, particularly among younger men.

Why are the results contradictory?

Differences in results may be due to several factors:

Dosage and frequency: Acute use may cause temporary changes, while chronic use may lead to the body adapting.
Individual differences: Age, genetics, and overall health can affect your response to THC.
Research methodology: Differences in sample size, control groups, and measurement techniques may lead to different conclusions.

For example, animal studies, such as those on primates, have shown that chronic THC use leads to reduced testicular size and lower testosterone levels, but these results do not always translate directly to humans.

Detailed analysis of the research

THC interacts with the endocannabinoid system, which can influence the production of hormones, including testosterone. Testosterone is produced primarily by the Leydig cells in the testes and regulated by pituitary hormones such as luteinizing hormone (LH). Increasing marijuana use, particularly among young men, has prompted scientists to investigate whether THC might lower testosterone levels. Analysis of available studies shows inconsistent results, requiring a deeper look at various aspects, such as acute vs. chronic use, dosage, and even interspecies differences.

Studies suggesting a decline in testosterone levels

Some studies, especially older or animal studies, indicate a potential negative effect of THC on testosterone levels:

A study from Oregon Health & Science University (2022) in primates showed that daily administration of THC for 7 months led to a reduction in testicular size by more than 50% and a significant reduction in testosterone levels, with a dose-dependent effect.
A reanalysis of data from the 1980s found that testosterone levels are reduced after both smoking a single joint and intravenous administration of THC, with a recovery time of at least 24 hours.
A study of over 2,000 infertile men found that marijuana users had lower plasma testosterone levels compared to non-users, although this did not affect sperm concentration or motility.

Key studies suggesting a decline in testosterone levels:

Test	Study group	A key find	Comments
OHSU, 2022	Primates (monkeys)	>50% decreased testicular size, lower testosterone	Chronic use, dose dependency
ScienceDirect, reanalysis	Men, existing data	Decrease in testosterone after acute use, returning after 24 hours	Simulation analysis, no new clinical data
Hims, the infertile study	>2000 infertile men	Lower testosterone levels in marijuana users	No effect on sperm concentration and motility

Studies suggesting no effect or an increase

Other studies, especially newer ones and those involving larger groups, indicate no significant effect or even an increase in testosterone levels:

A study based on NHANES data (2011–2012) from 1,577 men found no difference in testosterone levels between users and non-users, but recent users had slightly higher levels, particularly in the 18–29 age group.
A study from the World Journal of Urology (2020) found that men who used marijuana in the past year had higher testosterone levels, especially when using at least two or three times a month.
An ex vivo study on adult human testicular tissue showed that 48-hour or 9-day exposure to THC and CBD had no effect on testosterone production.

Key studies suggesting no effect or an increase:

Test	Study group	A key find	Comments
NHANES 2011–2012	1,577 men	Higher testosterone levels in recent users	Especially in the 18–29 age group, there is no overall difference
World Journal of Urology 2020	Male marijuana users	Higher testosterone levels with frequent use during the year	Adjusted for age, BMI, smoking status, etc.
WJMHO, ex vivo study	Human testicular tissue	No effect on testosterone production after 48h/9d	Ex vivo study does not reflect the full physiology

Systematic review and meta-analysis

A 2021 systematic review and meta-analysis (Belladelli et al.) analyzed nine studies with 4,787 men, 1,717 of whom were cannabis users. The results showed that the difference in testosterone levels between users and nonusers was small (SMD = -0.139, 95% CI: -0.413; 0.134, P = 0.318), indicating no clinically significant effect. After excluding one study (Kolodny et al.), the SMD was 0.0999 (P = 0.006), suggesting a small increase, but the effect size was very small.

Meta-analysis results:

Aspect	Result
Number of studies	9, 4787 men (1717 users)
Testosterone Difference (TD)	-0.139 (95% CI: -0.413; 0.134, P = 0.318)
Heterogeneity	High (I² = 87.22%)
After excluding Kolodny et al.	SMD = 0.0999 (P = 0.006), I² = 13.20%
Application	No clinically significant effect

Possible reasons for the discrepancy

Differences in results may be due to:

Frequencies and doses: Acute use may cause a temporary decline, while chronic use may lead to adaptation.
Interspecies differences: Animal studies, such as those on primates, show greater negative effects that do not always translate to humans.
Methodology: Differences in sample size, control groups, and measurement techniques may affect the results.

For example, a primate study found a dose-dependent decrease in testosterone with chronic use, but this was at doses consistent with heavy medical marijuana use in humans, which may not reflect typical use patterns.

Conclusions and recommendations

Current knowledge indicates that the effects of THC on testosterone levels are complex and inconsistent. Acute use may temporarily lower testosterone levels, but chronic use does not appear to have a significant clinical effect, with some studies even suggesting higher levels in recent users. A systematic review suggests that any effect is not clinically significant.

For marijuana users, especially those planning to have children or concerned about reproductive health, it's wise to consult a doctor, especially with long-term use. Monitoring hormone levels can help assess individual impact.

Final thoughts

The relationship between THC and testosterone requires further study, particularly in large groups, to better understand the long-term effects. As marijuana becomes increasingly popular, ongoing research will be crucial for hormonal health.