Does THC Lower Testosterone Levels? A Comprehensive Review of Research 2026

The belief that smoking marijuana lowers testosterone is commonly accepted in gyms and bodybuilding forums. Data in humans do not confirm this. The largest population study conducted on this issue found no difference in testosterone levels between users and non-users, and men who used marijuana most recently had even higher levels. A large Danish study showed similar results. There is a signal of influence, but it primarily concerns sperm rather than hormones, and it is much weaker than the popular narrative suggests. This text breaks down the available studies and shows which claims are supported by scientific work and which are repeated legends from the gym. For each number, we provide the work from which it originates.

KEY INFORMATION
• In the NHANES study involving 1577 men, no difference in testosterone levels was found between those who had ever used marijuana and those who had never used it.
• In the same study, testosterone was higher in men who had used marijuana most recently, which is contrary to popular belief.
• In the Danish study of 1215 young men, marijuana smokers had testosterone levels higher than non-users, at levels similar to cigarette smokers.
• The impact on sperm is better documented: using marijuana more than once a week was associated with a 28 percent lower sperm concentration.
• There is no meta-analysis combining studies on THC and testosterone, despite being cited in popular texts.
• The effect of CBD on hormonal regulation in humans is unstudied, and a review of studies on the male reproductive system reports adverse signals, mainly from animal studies.

Do human studies confirm that THC lowers testosterone?

No, not in the way it is repeated. The largest population study found no difference between marijuana users and those who have never used it, and where a difference was seen, testosterone was often higher in users. A clearer and more reproducible signal concerns sperm quality rather than hormone concentration.

It is important to separate two things that are often conflated in popular texts. The first is the acute reaction to a single dose, described in literature from the 1970s and 1980s, which subsides within hours. The second is the lasting hormonal state of a person who has been using marijuana regularly for years, measured in cross-sectional and cohort studies. The conclusion from the first does not automatically transfer to the second, and most circulating claims make exactly that leap.

Separately, it is worth mentioning what is not present in this field. There is no meta-analysis combining studies on marijuana and testosterone, although a supposed 2019 paper covering over three thousand men circulates in Polish texts. Searching in Europe PMC by title, author, and topic returns nothing that corresponds to this description, and the identifiers given alongside it lead to works from completely different fields. The statements in the rest of this article are therefore based on individual studies, named and verifiable.

This state of knowledge does not mean that THC is neutral for the hormonal system. It means that the claim of marijuana lowering testosterone does not have the support in human studies that it is attributed to, and a person planning health decisions should know this before, not after, making them.

How does the HPG axis work and where can THC interfere with it?

The hypothalamic-pituitary-gonadal axis regulates testosterone production. The hypothalamus pulsates GnRH, the pituitary responds with the release of LH and FSH, which stimulate Leydig cells to produce testosterone and Sertoli cells to support spermatogenesis. Cannabinoid receptors CB1 are present at every level of this axis.

This distribution of receptors is the reason why the hypothesis of THC’s influence on male hormones was proposed in the first place, and it is pharmacologically sensible. The endocannabinoid system participates in regulating male reproduction at the level of the hypothalamus, testes, and the sperm themselves, and in vitro and animal studies show disturbances in spermatogenesis, sperm motility, and acrosomal reaction after exposure to cannabinoids (du Plessis et al., Journal of Assisted Reproduction and Genetics, 2015).

However, the mechanism is not proof of effect. Between the observation that a receptor is present in tissue and the claim that a specific person has lower testosterone because of it lies the entire distance separating pharmacology from epidemiology. The same review work is largely based on animal models and cell studies, which use concentrations and exposure times difficult to relate to regular use.

It is worth remembering the direction of the relationship, as it returns later in the text. Activation of CB1 suppresses GnRH pulsation, so the expected effect of an acute dose of THC is a temporary drop in LH, and subsequently testosterone. However, the body has compensatory mechanisms, and it is these that determine what is seen in a blood test performed a week or a month later.

What did the largest population study show?

The strongest data comes from the American NHANES study, in which testosterone levels were measured by mass spectrometry in 1577 men and compared with reported marijuana use. No difference was found between those who had ever used it and those who had never done so.

The values were practically identical: 3.69 ng/ml in those who had ever used it versus 3.70 ng/ml in non-users, after accounting for confounding factors. The authors noted a dependence on how long ago the last regular use occurred, and this was in the opposite direction to what was expected: the closer to the study, the higher the testosterone. In the group of men aged 18 to 29, this relationship was stronger. The authors’ conclusion is straightforward: testosterone levels were higher in men who had used marijuana more recently (Thistle et al., Andrology, 2017).

This study has a peculiar career in the Polish-language internet. It is sometimes cited twice in the same text: once correctly, as evidence of no difference, and once as a supposed source of the claim of a decrease in testosterone in heavy users by 58 ng/dl. This second number does not appear in the paper, and its direction is opposite to what the paper states. You can recognize this maneuver by the fact that both versions refer to the same number of 1577 men, although they attribute it to different journals.

A similar result was obtained in an earlier study comparing hormone levels in 93 men and 56 women depending on the frequency of marijuana use, in which chronic use did not significantly affect the levels of any of the hormones studied (Block et al., Drug and Alcohol Dependence, 1991).

Did older studies say otherwise?

Yes, and that is where the whole belief comes from. In 1974, a paper was published in the New England Journal of Medicine describing reduced testosterone levels in men who heavily smoked marijuana. This is the source of the circulating thesis, repeated for half a century, despite subsequent studies not confirming it.

The work of Kolodny and colleagues exists and is real, but it is important to know what it was: a cross-sectional comparison of a group of chronic users with a control group, not an experiment in which someone smoked daily for four weeks under supervision. Popular summaries often attribute this second scheme to it, which it never had (Kolodny et al., New England Journal of Medicine, 1974).

The percentage of testosterone reduction given with this paper is not provided here, as it cannot be verified today in the available summary, and the numbers attributed to studies from that period are often distorted in repetitions. More important is what happened later: subsequent attempts at replication, including the above-mentioned study from 1991 and the NHANES study, did not reproduce that result.

A separate group consists of acute exposure studies from the 1970s and 1980s, in which a temporary drop in LH and testosterone was observed after THC administration, returning to baseline values within a day. Specific percentages of decline circulating in popular texts are usually given without identifying the source paper, so we do not repeat them here. The pattern of temporary inhibition is consistent with what is known about the role of CB1 receptors in the hypothalamus.

How does THC affect sperm quality?

Here the signal is clearer than in the case of hormones, although still ambiguous. In a Danish study of 1215 young men, using marijuana more than once a week was associated with a 28 percent lower sperm concentration and a 29 percent lower total sperm count, after accounting for confounding factors.

The participants were men aged 18 to 28, examined during mandatory military testing, of whom 45 percent had smoked marijuana in the past three months. The combination of marijuana with other intoxicating substances deepened the effect: sperm concentration was then lower by 52 percent, and total count by 55 percent. However, the same work notes something that rarely makes it into summaries: marijuana smokers had higher testosterone, at levels similar to cigarette smokers (Gundersen et al., American Journal of Epidemiology, 2015).

The picture is complicated by a study conducted at a fertility treatment center, involving 662 men and 1143 sperm samples. Men who had ever smoked marijuana had a higher sperm concentration than never-smokers, and the percentage of results below WHO reference values was less than half. Marijuana was not associated in this study with either sperm DNA integrity markers or sex hormones, except for reduced FSH. The authors concluded that their results were not consistent with a harmful effect of marijuana on testicular function (Nassan et al., Human Reproduction, 2019).

Two studies, two opposing directions, two different populations: young conscripts and men presenting with fertility issues. An honest conclusion is that the impact on sperm is possible and likely dose-dependent, but not established. If you are looking for factors with better-documented effects on sperm parameters, we have separately described what is known about zinc and sperm quality.

Does THC prolong the time to conception?

No, according to the largest study that examined this. In a North American cohort of couples planning pregnancy, no significant relationship was found between marijuana use by either the woman or the man and fertility measured by the chance of becoming pregnant in subsequent cycles.

The analysis included 4194 women, including 1125 couples, in which data was also provided by the partner, observed every eight weeks for a year or until pregnancy occurred. The fertility coefficients for marijuana use by the man were 0.87 for use less than once a week and 1.24 for more frequent use, and for women, practically 1.0 in both categories. The confidence intervals included the value of one, so none of these results are significant. The authors concluded that in this cohort, the relationship between marijuana use and fertility was negligible (Wise et al., Journal of Epidemiology and Community Health, 2018).

The number of 1125 couples is significant because in popular texts, the same cohort is sometimes attributed to a different journal and year, along with a claim of an eleven percent increase in time to conception in couples where the partner used marijuana. Such a result does not exist in this work, and its conclusion goes in the opposite direction. You can recognize the substitution by the characteristic number that travels between publications.

What does this mean practically for couples trying to conceive? That eliminating THC is not an intervention with proven effectiveness in shortening the time to conception, but it also costs nothing and falls within a reasonable precautionary principle. If there are real fertility issues, decisions should be based on sperm analysis and consultation with an andrologist, not on articles.

Is the effect of THC on the HPG axis reversible?

Everything known about the pharmacology of CB1 receptors suggests reversibility. Receptor activation ceases with the elimination of the substance, and the suppression of GnRH pulsation is not a structural change. However, hard clinical data on the rate of return are scarcer than popular recovery calendars suggest.

Acute exposure studies show a return of LH and testosterone to baseline values within a day after a single dose. For chronic use, there are significantly fewer such measurements, and specific time windows provided online, such as six to ten weeks for hormone normalization, usually come from articles that do not cite the source work. A physiological anchor that can be honestly provided is the length of the spermatogenesis cycle in humans, which is about 74 days. This explains why sperm parameters change more slowly than hormone concentrations.

THC is highly lipophilic and accumulates in fatty tissue, so its elimination in a daily user takes longer than in an occasional user. This is a well-described pharmacokinetic fact in toxicology, but specific detection windows depend on the testing method and laboratory cutoff threshold, so a single number cannot be provided for everyone. We have expanded on the topic of recovery after cessation in a separate text about the return of testosterone after stopping THC.

A practical piece of advice without pretending precision: if you are planning conception or want to exclude THC as a variable before hormonal testing, a three-month break covers a full spermatogenesis cycle and is sufficient for substance elimination. Not because the study indicated that number, but because it arises from physiology.

Does CBD affect testosterone the same way as THC?

Not the same way, but also not as is usually written. CBD has very weak affinity for the CB1 receptor, so it should not inhibit the HPG axis in the mechanism specific to THC. However, this does not mean that its hormonal safety has been demonstrated, as appropriate studies in humans have simply not been conducted.

This distinction is important because it is often blurred. Popular texts refer to a supposed 2020 review that would have shown no effect of CBD on testosterone at doses from 25 to 200 mg. A 2020 review dedicated to the effect of cannabidiol on the male reproductive system does indeed exist, but its conclusion is the opposite: exposure to CBD was associated with a reduction in testicular size, the number of germ and supporting cells in spermatogenesis, fertilization rates, and concentrations of hormones in the hypothalamic-pituitary-gonadal axis. The authors note that knowledge is limited, and most data comes from animal studies (Carvalho et al., Journal of Applied Toxicology, 2020).

This is confirmed by an independent review of the safety of cannabidiol, which explicitly lists the effect of CBD on hormones among the toxicological parameters requiring investigation (Iffland and Grotenhermen, Cannabis and Cannabinoid Research, 2017). The most commonly reported adverse effects of CBD in clinical trials are fatigue, diarrhea, and changes in appetite and body weight.

An honest summary of this section would therefore sound different than the industry would like. There is no human study that measures testosterone as an endpoint at typical supplemental doses of CBD, so it cannot be said either that it affects or that it does not affect. Sellers who present the latter version as a fact refer to a work that says something different. If you are looking for hemp oils, their current selection can be found in the oils category.

What does this mean for bodybuilding and strength sports?

Less than most trainees think. Since the largest studies do not show a decrease in testosterone in marijuana users, the argument about lost muscle mass due to hormone decline has no support in the data today. The reasons why THC may hinder training are different and less spectacular.

A review dedicated to cannabis and sports performance summarizes that studies on whole cannabis and THC show either no effect or a negative effect on performance, but there is simply a lack of rigorous studies to resolve the issue in athletes. In the case of CBD, the focus is on recovery, sleep, and pain, with none of these areas having been studied in athletic populations at a decent level (Burr et al., Sports Medicine, 2021).

The circulating number of a 27 percent reduction in delayed onset muscle soreness after 60 mg of cannabidiol is usually presented without citing the source paper and cannot be verified, so we do not repeat it here. This is a good example of how this market works: a specific number sounds more credible than an honest statement about the lack of data, so the specific number wins.

There remains the regulatory layer, which is clear. The World Anti-Doping Agency removed CBD from the list of banned substances in 2018, while THC remains a banned substance in competitions. For an athlete subject to anti-doping control, this distinction has practical significance regardless of how the hormone dispute ultimately resolves. If you are interested in what actually changes sperm parameters and testosterone in randomized studies, we have gathered data on ashwagandha and male fertility.

Which substances actually lower testosterone?

Since marijuana appears neutral in human studies, it is worth knowing what remains on the side of substances that lower testosterone in the same literature review. These are primarily alcohol, opioids, and anabolic-androgenic steroids, which are groups that act directly on the testes or the hypothalamic-pituitary axis.

A review dedicated to substance-induced hypogonadism separates these two mechanisms in a way that is decisive for this article. The first of these groups reduces testosterone production by disrupting the function of the testes or the hypothalamus and pituitary. The second group includes nicotine and amphetamines, along with cannabis: they change spermatogenesis through oxidative stress and apoptosis in testicular tissue, without being assigned a reduction in testosterone (Duca et al., Journal of Clinical Medicine, 2019).

This is exactly the division that emerges from the studies discussed earlier. Cannabis has documented signals on the sperm side and none on the hormone side, so it ends up where it should. A man who is concerned about testosterone and is looking for a single thing to change has a statistically greater chance of hitting by reducing alcohol than by quitting occasional smoking.

The authors also add one observation that is often overlooked in discussions about hormones. Substance-induced hypogonadism is potentially reversible, and identifying the cause is clinically significant because discontinuing the substance can reverse the symptom complex. This is an argument for starting with a thorough interview when testosterone is low, rather than jumping straight to a supplement.

What about THC exposure during pregnancy and in youth?

These are the only two areas where the precautionary principle takes precedence over the dispute about the strength of evidence. In both cases, it concerns periods when regulatory systems are just forming, and the effects of disruption can be permanent rather than transient. The recommendation here is simple and does not require determining how much any hormone changes.

During pregnancy, the recommendation is complete abstinence from cannabis, including during breastfeeding. Cannabinoids pass through the placenta and into breast milk, which is sufficient to not wait for hard evidence of harm before formulating a recommendation. It is worth noting that this also applies to CBD, even though there is even less data about it than about THC.

Adolescence is the second sensitive window. The endocannabinoid system participates in the maturation of circuits regulating hormone secretion, so intense exposure during this time is inherently riskier than in an adult. However, it should be added immediately that claims of permanent testosterone reduction in individuals who started before the age of seventeen are presented in popular texts without sources, and we have not found a study that confirms them.

For an adult man, the picture looks different. The hormonal system is fully mature, and the observed changes mostly subside after cessation of use. A broader overview of what is known about the long-term effects of cannabis use is described in the text about the long-term effects of cannabis use.

Frequently Asked Questions

Does THC actually lower testosterone levels in men?

Research in humans does not confirm this. In the NHANES study involving 1577 men, testosterone levels in marijuana users and non-users were practically identical, and in men who used most recently, even higher. Similarly, a Danish study of 1215 young men showed the same results.

How does THC affect the hypothalamic-pituitary-gonadal axis?

CB1 receptors are present at every level of this axis, and their activation suppresses the pulsatile release of GnRH, leading to lower LH and temporarily lower testosterone. This mechanism has mainly been described in animal studies and acute exposure studies in humans, where the effect subsided within a day.

Is the effect of THC on testosterone reversible?

Pharmacology suggests reversibility, as receptor activation ceases with the elimination of the substance. However, specific time windows provided online lack cited sources. The only number that can be honestly provided is the length of the spermatogenesis cycle in humans, approximately 74 days.

How does THC affect sperm count?

In a Danish study of 1215 young men, using marijuana more than once a week was associated with a 28 percent lower sperm concentration. However, in a study of 662 men from a fertility treatment center, the result was the opposite, and the authors concluded that their data did not indicate a harmful effect on testicular function.

Does marijuana use prolong the time to conception?

In a cohort of 4194 women, including 1125 couples, no significant relationship was found between marijuana use by either partner and the chance of becoming pregnant. The circulating claim of an 11 percent increase in time to conception does not originate from this work and contradicts its conclusion.

Does CBD affect testosterone the same way as THC?

CBD has very weak affinity for the CB1 receptor, so it should not act through the same mechanism. However, there is no human study measuring testosterone at typical supplemental doses, and a 2020 review reports adverse signals for cannabidiol, mainly from animal studies.

Does THC harm bodybuilders and strength athletes?

Not by lowering testosterone, as the data does not show this. Reviews indicate that cannabis and THC have either no effect or a negative effect on performance, with a clear lack of rigorous studies on athletes. Regulatory-wise, THC remains a banned substance in competitions, while CBD was removed from the list in 2018.

Is marijuana use safe during pregnancy?

No. During pregnancy and breastfeeding, complete abstinence from cannabis is recommended, including CBD. Cannabinoids pass through the placenta and into breast milk, which is sufficient to apply the precautionary principle without waiting for conclusive studies.

How does the balance of evidence look?

The answer to the question in the title is: there is currently no convincing data that THC lowers testosterone in humans. The largest population study found no difference, the Danish study of young men showed higher levels in smokers, and the older 1974 paper on which the entire circulating thesis is based has not been replicated.

The signal that has survived scrutiny concerns sperm and is also inconsistent. Danish conscripts using marijuana more than once a week had a 28 percent lower sperm concentration, but men from the fertility treatment center had higher concentrations. The impact on fertility measured by time to conception proved insignificant in the largest cohort.

It is worth remembering the method, as it will be useful in every subsequent text about supplements. A number without a cited work is not data, but an ornament. The same number of participants traveling between different journals and years is a signal that someone has multiplied one study into several citations. A conclusion presented in the opposite direction to the conclusion of the source work occurs more often than one might expect.

From a practical point of view, this is not an encouragement to smoke daily. THC affects sleep, and through sleep, recovery, remains a banned substance in professional sports, and should not be used during pregnancy or adolescence. The argument about testosterone is simply not the one that justifies this, and building health decisions on non-existent numbers ends badly regardless of which way those numbers point.

This article is for informational and educational purposes only and does not constitute medical advice. Before starting to use cannabis or CBD for therapeutic purposes, consult a doctor, especially if you are taking other medications, are pregnant, or breastfeeding.

Author: Michał Waluk · Published: 2026-04-27 · Updated: 2026-08-10