Chronic THC caused significant testicular shrinkage and hormone changes in monkeys
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.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?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?
Trust & Context
- Key Stat:
- 58% testicular volume decrease; dose-dependent hormonal shift
- Evidence Grade:
- Animal study with only 6 subjects, but uses a closely related primate model with dose-response data.
- Study Age:
- Published in 2022.
- Original Title:
- Chronic exposure to delta-9-tetrahydrocannabinol impacts testicular volume and male reproductive health in rhesus macaques.
- Published In:
- Fertility and sterility, 117(4), 698-707 (2022)
- Authors:
- Hedges, Jason C(4), Hanna, Carol B(2), Bash, Jasper C(2), 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
- Database ID:
- RTHC-03906
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Can THC affect male fertility?
In this monkey study, daily THC edibles caused a 58% decrease in testicular volume and significant drops in testosterone, suggesting primary testicular failure. Whether this occurs in humans is not yet confirmed.
Did THC affect sperm quality?
Despite dramatic testicular atrophy and hormone changes, sperm motility, morphology, and concentration did not significantly change in this study, suggesting possible functional compensation.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03906APA
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
MLA
Hedges, Jason C, et al. "Chronic exposure to delta-9-tetrahydrocannabinol impacts testicular volume and male reproductive health in rhesus macaques.." Fertility and sterility, 2022. https://doi.org/10.1016/j.fertnstert.2021.12.028
RethinkTHC
RethinkTHC Research Database. "Chronic exposure to delta-9-tetrahydrocannabinol impacts tes..." RTHC-03906. Retrieved from https://rethinkthc.com/research/hedges-2022-chronic-exposure-to-delta9tetrahydrocannabinol
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.