Mice exposed to THC during adolescence had reduced sperm counts, more testicular damage, and impaired testosterone production as young adults, while the same exposure in adulthood had milder effects.
Young men who use cannabis and anyone concerned about reproductive health effects of adolescent cannabis use.
Adolescent THC exposure impaired both sperm production and testosterone synthesis, while adult exposure only affected testosterone
What the researchers found
Adolescent THC exposure (postnatal days 30-43) decreased sperm numbers, increased seminiferous tubule degeneration, and impaired steroidogenesis with dysregulated expression of key enzymes (StAR protein and CYP17A1). Adult exposure (postnatal days 70-83) reduced testosterone levels but did not affect sperm production or tubule structure. Both CB1 and CB2 receptors were confirmed present in the testis.
Why it matters
Cannabis use typically begins during adolescence, and this study provides biological evidence that the developing reproductive system may be more vulnerable to THC than the mature one, with effects persisting weeks after exposure stops.
The numbers in context
THC dose: 5 mg/kg daily for 14 days. Adolescent exposure: PND 30-43, harvested at PND 70. Adult exposure: PND 70-83, harvested at PND 110. Adolescent group: decreased sperm, increased tubule degeneration, dysregulated StAR and CYP17A1. Both groups: decreased testosterone. Adult group: no sperm or structural effects.
How the study worked
C57BL/6N male mice received daily THC injections (5 mg/kg) or vehicle during either adolescence (PND 30-43) or adulthood (PND 70-83). Testes were harvested 27 days after the last injection. Assessments included sperm counts, testicular histology, testosterone levels, and expression of endocannabinoid system components and steroidogenic enzymes.
What this study cannot tell us
Mouse model may not directly translate to humans. The 5 mg/kg dose via injection does not mimic typical human consumption patterns. Only one dose level was tested. Long-term recovery beyond 27 days was not assessed.
How to read the evidence
Preliminary: single animal study with one dose level and one time point, though well-designed with appropriate controls.
When this study was published
2025 study.
The bigger picture
This adds to evidence that adolescent biology responds differently to cannabinoids than adult biology. The finding that testicular damage persisted nearly a month after THC stopped suggests the effects may not be quickly reversible during development.
Questions still open
- Are these effects reversible with longer recovery periods? At what dose threshold do these reproductive effects begin? Do these findings translate to human adolescents who use cannabis?
Common questions
Did THC permanently damage the testes?
Why was adolescent exposure worse than adult?
Read the original research
Adolescent exposure to Δ9-tetrahydrocannabinol impairs testicular function in young adult male mice.
Toxicological sciences : an official journal of the Society of Toxicology, 208(1), 82-94
Citation
Lim, Jinhwan; Quach, Caitlin; Nguyen, Julie; Rizk, Andrew; Getze, Samantha; Jung, Kwang-Mook; Mahler, Stephen V; Piomelli, Daniele; Luderer, Ulrike. (2025). Adolescent exposure to Δ9-tetrahydrocannabinol impairs testicular function in young adult male mice.. Toxicological sciences : an official journal of the Society of Toxicology, 208(1), 82-94. https://doi.org/10.1093/toxsci/kfaf035
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