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.
Read this if you use cannabis and are concerned about fertility or are planning to conceive.
Most studies associate cannabis use with lower sperm concentrations
What the researchers 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.
Why it 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 numbers in context
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 the study worked
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.
What this study cannot 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.
How to read the evidence
Mini-review covering both preclinical and clinical evidence provides moderate evidence, with the sperm concentration finding supported across multiple studies despite hormonal inconsistencies.
When this study was published
Published in 2018. Subsequent studies have continued to examine cannabis-fertility relationships with mixed but generally cautionary findings.
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.
Questions still open
- 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?
Common questions
Does cannabis affect male fertility?
Should men stop cannabis before trying to conceive?
Read the original research
Adverse Effects of Cannabis on Male Reproduction.
European urology focus, 4(3), 324-328
Citation
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
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