Frequently asked questions
Do cannabis or THC have a negative influence on sex hormones and sperms?
Wayne Hall, Nadia Solowij & Jim Lemon
High doses of THC probably disturb the male and female reproductive systems in animals. They reduce secretion of testosterone, and hence reducing sperm production, motility, and viability in males. It is uncertain whether these effects also occur in humans. Studies in humans have produced both positive and negative evidence of an effect of cannabinoids on testosterone, for reasons that are not well understood. Hollister has argued that the reductions in testosterone and sperm production observed in the positive studies are probably of “little consequence in adults”, although he conceded that they could be of “major importance in the prepubertal male who may use cannabis.” The possible effects of cannabis use on testosterone and spermatogenesis may be most relevant to males whose fertility is already impaired for other reasons, e.g. a low sperm count.
(Please note: This text has been taken from a scientific article. Some sentences have been changed to improve understandability.)
Hall W, Solowij N, Lemon J. The Health and Psychological Consequences of Cannabis Use. National Drug Strategy Monograph Series No. 25. Canberra: Australian Government Publishing Service, 1994.
In human males, cannabis smoking has been shown to decrease blood levels of the three hormones LH, FSH, and testosterone. Moreover, an increased incidence of low sperm count has been reported in men who were heavy marijuana smokers. Other studies did not find measurable differences in men who were light or heavy marijuana users. Acute THC treatment produces a consistent and significant dose- and time-related decrease in LH and testosterone levels in male rodents. In the male rhesus monkey, an acute dose of THC produced a 65% reduction in blood testosterone levels by 60 min of treatment that lasted for approximately 24 hr.
(Please note: This text has been taken from a scientific text. Some sentences have been changed to improve understandability.)
Murphy L. Hormonal system and reproduction. In: Grotenhermen F, Russo E, eds. Grotenhermen, F., Russo, E. (eds.): Cannabis and cannabinoids. Pharmacology, toxicology, and therapeutic potential. Haworth Press, Binghamton/New York 2001, in press.
Lynn Zimmer & John Morgan
By giving large doses of THC to animals, researchers have produced appreciable effects on sex hormone levels. However, the effects vary from one study to another, depending on the dose and timing of administration. When effects occur, they are temporary. (. ) In neither male nor female animals have researchers produced permanent harm to reproductive function from either acute or chronic marijuana administration. (. ) There is no convincing evidence of infertility related to marijuana consumption in humans. There are no epidemiological studies showing that men who use marijuana have higher rates of infertility than men who do not. Nor is there evidence of diminished reproductive capacity among men in countries where marijuana use is common. It is possible that marijuana could cause infertility in men who already have low sperm counts, However, it is likely that regular marijuana users develop tolerance to marijuana’s hormonal effects. (. ) Marijuana has neither a masculinizing effect in females nor a feminizing effects in males.
Zimmer L, Morgan JP. Marijuana Myths Marijuana Facts. A review of the scientific evidence. New York/San Francisco: The Lindesmith Center, 1997.
House of Lords
Animal experiments have shown that cannabinoids cause alterations in both male and female sexual hormones; but there is no evidence that cannabis adversely affects human fertility, or that it causes chromosomal or genetic damage.
House of Lords Select Committee on Science and Technology. Cannabis. The scientific and medical evidence. London: The Stationery Office, 1998.
Is There a Link between Low Testosterone and Chronic Marijuana Use?
Some experts are concerned that efforts to legalize medical marijuana may lead to an increase in the incidence of low testosterone and related conditions such as gynecomastia.
Will efforts to legalize medical marijuana lead to an increase in the incidence of low testosterone and related conditions such as gynecomastia?
Assuming greater availability leads to greater usage among at-risk groups, some doctors expect the answer to that question may be “yes.”
“Although the association between marijuana and gynecomastia hasn’t been conclusively proven, it appears very plausible,” wrote Anthony Youn, MD, a plastic surgeon from the Detroit area, in a column for CNN Health.
“For this reason, the majority of plastic surgeons I’ve consulted with routinely inquire with their gynecomastia patients about cannabis use and recommend they stop smoking pot immediately.”
The uncertainty expressed by Youn and other doctors stems from conflicting research.
Some studies have found that frequent marijuana use leads to dramatic reductions in testosterone and, thus, to ancillary problems ranging from weight gain to infertility. Others have found no impact.
Research on the subject dates back at least four decades. Indeed, it was April 1974 when a team of authors that included the famed sex researcher William H. Masters published a much-cited piece in The New England Journal of Medicine.
That study found dramatic differences in hormone levels between a control group and 20 carefully selected marijuana smokers. Mean (± S.E.M.) plasma testosterone among 20 marijuana smokers, aged 18 to 28 was 416 ± 34 ng per 100 ml. For a control group of aged-matched men, the mean was 742 ± 29 ng per 100 ml. Moreover, the researchers noted, the quantity of marijuana smoked correlated strongly and negatively with testosterone levels.
Later that same year, the Journal published the account of another study by another team, this one led by Jack H. Mendelson, MD, that found no relationship between any level of marijuana use and testosterone levels.
Among 27 smokers in that three-week study no statistically significant changes in plasma testosterone levels were observed during and after the smoking period as compared with the pre-smoking base-line levels.
Moreover, the mean pre-use testosterone level of 12 casual users was 988 ±93 ng per 100 ml, while the mean pre-use level of 15 heavy users was higher — 1115 ±69 ng per 100 ml.
An additional 40 years of follow-up research has yielded more studies but very little additional clarity, at least among humans.
Among animals, however, trials show conclusively that THC, the active ingredient in marijuana, lowers testosterone, throws testosterone and estrogen out of balance and creates a host of problems.
“The risks far outweigh man boobs,” said Gregory Buford, MD, a plastic surgeon from Denver who worries about the effects of marijuana legalization despite the potential benefits to his breast-reduction business. “Estrogen dominance in a male has been clearly shown to increase the risk for cardiac events, stroke, and early death.”
The failure to reach definitive conclusions on marijuana’s medical effects, not just on testosterone but on a wide range of factors, stems largely from the difficulties of performing trials on an illegal substance.
As the drug creeps toward legalization, medical professionals expect better trials that will provide better guidance about the wisdom of further deregulation.
“My hope,” Buford said, “is that the medical profession will begin studying the potential link between frequent marijuana use, testosterone and estrogen levels and determine just how concerned we really should be.”Some experts are concerned that efforts to legalize medical marijuana may lead to an increase in the incidence of low testosterone and related conditions such as gynecomastia. ]]>