Cannabis and Men's Health: Does Long-Term THC Use Lower Testosterone Levels and Affect Sexual Function?

The effects of chronic cannabis use on male hormones, specifically testosterone and reproductive function, are a major area of concern, although the scientific literature itself is "very controversial" and "super mixed".

Effects on Hormones:

• Testosterone Suppression: Chronic cannabis use, defined as more than twice a week, does appear to reduce testosterone significantly. It seems that, at least in some studies from the 1970s, transient dips in testosterone were observed after consumption, though levels often stayed within the normative range. However, most studies point to reduced levels of testosterone with chronic use.
• Aromatization and Estrogen Increase: Chronic smoking of cannabis appears to elevate aromatase enzymes, which are the enzymes that convert testosterone into estrogen. This hormonal shift means that cannabis increases estrogen and reduces testosterone. The literature on aromatization is mixed, and it is not fully understood.
• Prolactin Elevation: Smoking cannabis significantly increases prolactin levels in both men and women, especially when done more than twice a week. Since prolactin is mutually inhibitory with dopamine, elevated prolactin levels will reduce dopamine and, consequently, testosterone. Edible forms of marijuana, however, appear not to have as much of a prolactin elevating effect.

Effects on Reproductive Function:

• Reduced GnRH: THC, but not CBD, is known to be strongly inhibitory for gonadotropin-releasing hormone (GnRH). GnRH signals the pituitary gland to release Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH).
• Impaired Sperm Production: The reduction in LH and FSH caused by THC leads to reduced levels of testosterone and sperm production in males. Chronic use (more than twice per week, especially high doses of high-potency THC) seems to alter sperm motility and sperm health and function.
• Gynecomastia: The hormonal changes (reduced testosterone, increased estrogen) might partially explain gynecomastia (development of breast tissue) that occurs in about 35% of males, particularly young males. However, some experts note that developing breast tissue is not a typical side effect and they have not seen any compelling evidence for it in the scientific community.

Sexual Desire and Arousal:

• The effects of cannabis on sexual desire are highly divergent among individuals.
• Prolactin is the key predictor: Whether cannabis increases or suppresses sexual desire depends on how an individual’s prolactin levels react to THC ingestion.
• People whose prolactin levels go up in response to cannabis (the majority of smokers) typically do not experience activation of brain areas associated with sexual arousal and report feeling less sexually aroused.
• People who are in the subset whose prolactin levels do not go up may experience increased sexual arousal.

Men are highly worried that chronic, long-term use is causing slowly lowered testosterone levels and subsequent issues like sexual dysfunction ("need testosterone to get a boner fellas") and mood disturbances ("the grumpys"). They are looking for clarity on the mechanisms, particularly regarding gynecomastia (male breast development) and the observed hormonal changes. Furthermore, individuals who are actively trying to maximize fertility or conceive are asking if THC use affects sperm quality and if cannabinoid receptors are present on reproductive organs.

If you are a male chronic user concerned about low testosterone, reduced libido, or sperm quality, cessation of cannabis use is advisable to allow the reproductive system to reset. Given that smoking cannabis significantly elevates prolactin (which suppresses testosterone and dopamine), switching to edible forms might be a preferable route of administration, as preliminary evidence suggests edibles may not have as much of a prolactin elevating effect.

• Andrew Huberman: Provided detailed mechanistic explanations on the hormonal cascade. He confirmed that chronic smoking increases prolactin, which reduces dopamine and testosterone. He explained that THC strongly inhibits GnRH, impairing the release of LH/FSH needed for testosterone and sperm production. He acknowledged the controversial nature of the literature but pointed to the prevalence of gynecomastia (breast tissue development) in chronic male users due to elevated aromatase and estrogen. Huberman also resolved the libido controversy by identifying prolactin reactivity as the determinant of whether cannabis increases or suppresses sexual arousal.
• Dr. Matthew Hill: Dr. Hill noted that the data on cannabis's effect on hormones like testosterone and estrogen is "super mixed" and "not super clean cut". He confirmed that some studies suggest transient dips in testosterone. He stated he has not seen compelling evidence that gynecomastia is a typical side effect that men would experience. He agreed that if a couple is struggling to conceive, they should definitely cut cannabis use to eliminate a potential variable affecting sperm quality.
• Institute of Human Anatomy: Confirmed that CB2 receptors are found in the tissues of the body, including the genitals, and specifically on both male (testes) and female (uterus) reproductive tissues.

If experiencing low libido or sexual dysfunction, abstain from smoking cannabis to prevent the prolactin increase that suppresses dopamine and testosterone.

• Mistake: Believing cannabis is an aphrodisiac for everyone and increasing dosage to boost desire.
  Fix: Cannabis is only an aphrodisiac for people whose prolactin levels do not increase in response to THC. If you experience suppressed desire, your prolactin is likely high, and increasing THC will only suppress dopamine further.
• Mistake: Assuming that smoking cannabis is harmless to reproductive health because a friend conceived while high.
  Fix: While conception is possible, chronic use alters sperm motility and function and reduces necessary hormones (GnRH, LH, FSH). If fertility is a concern, abstinence is the prudent approach.
• Mistake: Assuming that cannabinoid receptors in the reproductive organs mean cannabis benefits them.
  Fix: The existence of CB2 receptors on the testes and uterus means THC can bind there, but its strong inhibitory action on GnRH (which regulates reproductive hormones) suggests a disruptive, rather than beneficial, effect on the system's normal function.

The sources clearly indicate that long-term, chronic cannabis use, especially via smoking, creates a hormonal environment—marked by reduced testosterone, elevated estrogen, and high prolactin—that is detrimental to male reproductive and sexual health. While the acute psychoactive effects on sexual desire are highly personalized (depending on prolactin reactivity), the overall biological toll on the endocrine system is documented to reduce key hormones (GnRH, LH, FSH) needed for sperm and testosterone production, compelling those concerned with fertility or low libido to cease chronic use.