Rhesus macaques given daily THC edibles experienced a 58% decrease in testicular volume and significant drops in testosterone, in a dose-dependent pattern suggestive of primary testicular failure.
Men using cannabis who are concerned about fertility, reproductive health researchers, and clinicians counseling male patients.
58% testicular volume decrease; dose-dependent hormonal shift
What the researchers found
For each 1 mg/7 kg/day increase in THC dose, bilateral testicular volume decreased by 11.8 cm3. Total average bilateral testicular volume decreased by 58%. Testosterone and estradiol decreased significantly while gonadotropins (FSH, LH) and prolactin increased, a hormonal pattern consistent with primary testicular failure.
Why it matters
This is the first nonhuman primate study to demonstrate dose-dependent testicular atrophy from THC exposure. The hormonal changes suggest the testes themselves are being damaged, not just hormonal signaling from the brain.
The numbers in context
6 macaques. 58% decrease in average bilateral testicular volume. Testosterone decreased by 1.49 ng/mL per dose increase. Estradiol decreased by 3.8 pg/mL. FSH, LH, and prolactin all increased. No significant changes in sperm parameters.
How the study worked
Six adult male rhesus macaques (ages 8-10) received daily edible THC at medically and recreationally relevant doses. Testicular volume, hormone levels, and semen parameters were measured.
What this study cannot tell us
Very small sample of 6 animals. Animal results may not directly translate to humans. Semen parameters did not change, which may indicate functional compensation. Unknown whether effects reverse after THC discontinuation.
How to read the evidence
Animal study with only 6 subjects, but uses a closely related primate model with dose-response data.
When this study was published
Published in 2022.
The bigger picture
While these results come from monkeys, rhesus macaques are among the closest models to human reproductive biology. The dose-dependent pattern and hormonal profile raise legitimate questions about fertility in men who use cannabis regularly.
Questions still open
- Are these testicular changes reversible after stopping THC? Do human cannabis users show similar hormonal patterns? Why did sperm parameters remain unchanged despite significant testicular atrophy?
Common questions
Can THC affect male fertility?
Did THC affect sperm quality?
Read the original research
Chronic exposure to delta-9-tetrahydrocannabinol impacts testicular volume and male reproductive health in rhesus macaques.
Fertility and sterility, 117(4), 698-707
Citation
Hedges, Jason C; Hanna, Carol B; Bash, Jasper C; Boniface, Emily R; Burch, Fernanda C; Mahalingaiah, Shruthi; Roberts, Victoria H J; Terrobias, Juanito Jose D; Mishler, Emily C; Jensen, Jared V; Easley, Charles A; Lo, Jamie O. (2022). Chronic exposure to delta-9-tetrahydrocannabinol impacts testicular volume and male reproductive health in rhesus macaques.. Fertility and sterility, 117(4), 698-707. https://doi.org/10.1016/j.fertnstert.2021.12.028
Explore the wider topic
- How to Talk to Your Teenager About Weed (Without Losing Them)
- My Kid's Friends Smoke Weed: A Parent's Guide
- I Smoke Weed But Don't Want My Kids To: Navigating the Hypocrisy
- Quitting Weed as a Parent: Why It Is the Hardest and Most Important Quit
- Quitting Weed as a Teen or Young Adult
- My Kid Is Smoking Weed: A Parent's Guide