Cannabis and Male Fertility: What the Science Actually Shows

A 2025 narrative review published in Maturitas maps the complex, double-edged role of the body’s endocannabinoid system in male reproductive health, examining evidence from preclinical and human studies on erectile function, spermatogenesis, prostatic inflammation, hormonal regulation, and prostate cancer biology, while highlighting the risks associated with chronic exogenous THC use.

Why This Matters

Male infertility affects an estimated one in six couples globally, and its causes remain poorly understood in a substantial proportion of cases. At the same time, cannabis legalization continues to expand worldwide, increasing population-level exposure to exogenous cannabinoids among men of reproductive age. Understanding how the endocannabinoid system intersects with male reproductive biology is therefore a pressing clinical and public health question. This review arrives at a moment when both patient inquiries and prescriber uncertainty about cannabis and fertility are intensifying.

Clinical Summary

The endocannabinoid system, composed of CB1 and CB2 receptors, the endogenous ligands anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and the degradative enzymes FAAH and MAGL, is expressed throughout the male reproductive tract. A narrative review by researchers publishing in Maturitas (2025) synthesizes preclinical, animal, and human literature to argue that this system plays a homeostatic role in several domains of male reproductive physiology. CB1 receptor activation in the corpus cavernosum appears to promote smooth muscle relaxation and vasodilation relevant to penile erection, while CB2 receptor signaling in prostatic tissue may reduce pro-inflammatory cytokine release, suggesting potential therapeutic relevance for conditions such as erectile dysfunction and chronic prostatitis.

However, the review also presents evidence that chronic exogenous THC exposure disrupts spermatogenesis, reduces sperm motility and quality, and causes hormonal imbalances including testosterone dysregulation. Some data suggest cannabinoids may influence prostate cancer cell proliferation, though the mechanisms remain poorly characterized. Critically, the evidence base underlying these claims is heavily weighted toward preclinical and animal models, with limited and often inconsistent human data. The review itself is non-systematic, lacking protocol registration, PRISMA adherence, and formal risk-of-bias assessment of included studies. The authors explicitly call for additional mechanistic research and longitudinal human studies before cannabinoid-based therapies or definitive risk warnings can inform clinical or policy recommendations.

Dr. Caplan’s Take

This review does a reasonable job of cataloging the biological plausibility behind both the therapeutic promise and the reproductive risks of cannabinoid signaling in men. The mechanistic logic connecting CB1 activation to erectile physiology and CB2 modulation to prostatic inflammation is genuinely interesting. But the gap between “biologically plausible” and “clinically actionable” remains wide. I hear regularly from male patients who want to know whether their cannabis use is affecting their fertility or sexual function, and the honest answer is that we still cannot give them a confident, data-driven response based on what exists in the human literature.

In practice, when a male patient of reproductive age asks me about cannabis and fertility, I share what the preclinical data suggest about chronic THC exposure and sperm parameters, and I recommend caution, particularly for men actively trying to conceive. I do not overstate the evidence by presenting these findings as confirmed in humans, but I also do not dismiss the signal. For patients with erectile dysfunction or prostatitis, I point them toward established treatments rather than cannabinoid-based approaches, which remain investigational at best. The science is moving, but it has not arrived.

Clinical Perspective

This review sits at an early stage of the research arc, consolidating mechanistic hypotheses rather than confirming clinical effects. It reinforces prior preclinical observations that the endocannabinoid system participates in regulating smooth muscle tone in erectile tissue and inflammatory cascades in the prostate. It also aligns with the growing body of animal data suggesting chronic THC exposure impairs spermatogenesis. However, the absence of systematic methods means the review cannot reliably indicate how consistent, reproducible, or large these effects are across the existing literature. Clinicians should not treat any of its directional claims as sufficient basis for therapeutic recommendations or categorical risk warnings to patients.

From a pharmacological and safety standpoint, clinicians should be aware that THC’s effects on the hypothalamic-pituitary-gonadal axis, including potential suppression of GnRH pulsatility and downstream testosterone production, could compound the effects of other medications or conditions already impairing reproductive hormone balance. This is particularly relevant for patients on opioids, anabolic steroids, or certain antipsychotics. The single most actionable recommendation at present is to counsel male patients of reproductive age who use cannabis regularly that preclinical evidence raises concerns about sperm quality and hormonal function, and that minimizing use during active conception efforts is a prudent, evidence-informed step even if definitive human proof remains lacking.

Study at a Glance

Study Type

Narrative review

Population

Preclinical models (in vitro, animal) and human males (epidemiological and clinical data)

Intervention

Endocannabinoid system modulation; exogenous cannabinoid (primarily THC) exposure

Comparator

Not applicable (narrative synthesis)

Primary Outcomes

Erectile function, spermatogenesis, sperm quality, hormonal balance, prostatic inflammation, prostate cancer cell proliferation

Sample Size

Not reported (no formal count of included studies)

Journal

Maturitas

Year

2025

DOI

10.1016/j.maturitas.2024.108156

Funding Source

Not reported

What Kind of Evidence Is This

This is a narrative review, which occupies a relatively low position in the evidence hierarchy compared to systematic reviews, meta-analyses, or randomized controlled trials. While it describes a structured search across four databases, it does not follow systematic review protocols such as PRISMA, includes no protocol registration, and performs no formal quality appraisal of included studies. The most important inference constraint this imposes is that its conclusions reflect the authors’ interpretive synthesis rather than a reproducible, bias-controlled assessment of the evidence, and weak and strong studies may be weighted equivalently.

How This Fits With the Broader Literature

The review’s findings are broadly consistent with prior work. A 2015 meta-analysis by Payne and colleagues found associations between cannabis use and altered semen parameters, though the effect sizes were small and inconsistent. Similarly, preclinical work by Grimaldi and colleagues (2013) demonstrated endocannabinoid involvement in sperm cell biology, and Hedlund and colleagues have characterized CB1 expression in human erectile tissue. The current review extends this landscape by attempting to integrate disparate mechanistic threads into a unified framework spanning erectile, spermatogenic, hormonal, and prostatic domains.

What remains unresolved is whether the mechanistic signals identified in animal and in vitro models translate meaningfully to human reproductive outcomes at real-world exposure levels. The review does not challenge prior findings so much as repackage them, underscoring the persistent absence of large, well-controlled longitudinal human studies that could move these hypotheses toward clinical certainty.

Common Misreadings

The most likely overinterpretation of this review is concluding that cannabis use has been proven to cause male infertility or that endocannabinoid-based therapies are a validated treatment for erectile dysfunction or prostatitis. Neither claim is supported by the evidence presented. The review synthesizes preclinical signals and observational associations, not causal proof from controlled human trials. Similarly, readers should not assume that because the endocannabinoid system is involved in erectile physiology, supplementing or modulating it externally would safely or reliably improve function. The distance between receptor-level biology and a therapeutic intervention is substantial and has not been bridged here.

Bottom Line

This narrative review usefully maps the endocannabinoid system’s broad involvement in male reproductive physiology and identifies plausible mechanisms through which chronic THC exposure could impair fertility. It does not establish causation, quantify risk, or validate therapeutic approaches. For clinicians, its primary contribution is framing a scientific conversation that remains hypothesis-generating. Counsel patients honestly about the preclinical signal, especially those trying to conceive, but do not treat these findings as settled science.

References

1. Review article discussed: Maturitas, 2025. DOI: 10.1016/j.maturitas.2024.108156