Most studies associate cannabis use with lower sperm concentrations, though evidence on sex hormones is contradictory
A review of cannabis effects on male reproduction found that while evidence on reproductive hormones is contradictory, most studies associate cannabis use with lower sperm concentrations, suggesting a negative impact on fertility potential.
Quick Facts
What This Study Found
Researchers reviewed the effects of cannabis on clinical markers of male fertility and the endocannabinoid system's role in reproductive function.
The endocannabinoid system plays important roles in sex hormone production, sperm production (spermatogenesis), and sperm function. Both CB1 and CB2 cannabinoid receptors are expressed in testicular tissue and on sperm cells.
Regarding sex hormones (testosterone, LH, FSH), the evidence was contradictory. Some studies showed cannabis-associated decreases, others showed no effect, and some showed increases.
However, the evidence was more consistent for sperm parameters: most studies associated cannabis use with lower sperm concentrations. This suggests a negative impact on male fertility potential, even if the hormonal mechanisms remain unclear.
The review was motivated by two converging trends: increasing cannabis use as regulations relax worldwide, and declining semen quality observed in developed countries, with couples increasingly delaying conception.
Key Numbers
CB1 and CB2 receptors expressed in testicular tissue and sperm. Most studies show lower sperm concentrations with cannabis use. Evidence on testosterone, LH, and FSH is contradictory across studies.
How They Did This
Mini-review of published studies on cannabis effects on male reproductive hormones, sperm parameters, and the role of the endocannabinoid system in male reproductive function.
Why This Research Matters
With cannabis use increasing and couples delaying conception, understanding cannabis effects on sperm is increasingly relevant. The consistent finding of lower sperm concentrations, despite contradictory hormone data, provides practical information for men of reproductive age.
The Bigger Picture
The decline in semen quality observed in developed countries coincides with increasing cannabis use, though the review does not claim causation. If cannabis does reduce sperm concentration, the effect compounds with other factors (environmental toxins, obesity, delayed reproduction) that are already pressuring male fertility.
What This Study Doesn't Tell Us
Mini-review format covers breadth rather than depth. The contradictory hormone findings may reflect different study designs, cannabis types, doses, and populations. Most human studies are observational and cannot establish causation. Effects on assisted reproduction outcomes (IVF success) are not well studied.
Questions This Raises
- ?Are the sperm concentration effects reversible with cannabis cessation?
- ?Do different cannabinoids (THC vs. CBD) have different effects on male reproduction?
- ?At what frequency or duration of use do sperm effects become clinically significant?
Trust & Context
- Key Stat:
- Most studies associate cannabis use with lower sperm concentrations
- Evidence Grade:
- Mini-review covering both preclinical and clinical evidence provides moderate evidence, with the sperm concentration finding supported across multiple studies despite hormonal inconsistencies.
- Study Age:
- Published in 2018. Subsequent studies have continued to examine cannabis-fertility relationships with mixed but generally cautionary findings.
- Original Title:
- Adverse Effects of Cannabis on Male Reproduction.
- Published In:
- European urology focus, 4(3), 324-328 (2018)
- Authors:
- Hsiao, Philip, Clavijo, Raul I
- Database ID:
- RTHC-01696
Evidence Hierarchy
Summarizes existing research on a topic.
What do these levels mean? →Frequently Asked Questions
Does cannabis affect male fertility?
Most studies reviewed found cannabis associated with lower sperm concentrations, suggesting a negative impact. However, evidence on sex hormones (testosterone, LH, FSH) is contradictory, with some studies showing decreases and others showing no effect.
Should men stop cannabis before trying to conceive?
This review suggests it may be worth considering, given the consistent finding of lower sperm concentrations. The review does not specify a timeline for recovery, but sperm production cycles take approximately 74 days.
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Cite This Study
https://rethinkthc.com/research/RTHC-01696APA
Hsiao, Philip; Clavijo, Raul I. (2018). Adverse Effects of Cannabis on Male Reproduction.. European urology focus, 4(3), 324-328. https://doi.org/10.1016/j.euf.2018.08.006
MLA
Hsiao, Philip, et al. "Adverse Effects of Cannabis on Male Reproduction.." European urology focus, 2018. https://doi.org/10.1016/j.euf.2018.08.006
RethinkTHC
RethinkTHC Research Database. "Adverse Effects of Cannabis on Male Reproduction." RTHC-01696. Retrieved from https://rethinkthc.com/research/hsiao-2018-adverse-effects-of-cannabis
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.