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Systematic review finds cannabis may negatively affect male fertility

Systematic ReviewModerate evidence
The takeaway

A systematic review found the strongest evidence that cannabis reduces sperm count and concentration, induces abnormal sperm morphology, reduces motility, and inhibits fertilizing capacity, though testosterone effects remain unclear.

Men of reproductive age who use cannabis, fertility clinicians, and researchers studying reproductive health.

Cannabis linked to reduced sperm count, motility, and fertilizing capacity

What the researchers found

Cannabis was associated with reduced sperm count and concentration, abnormal morphology, reduced motility and viability, and inhibited capacitation and fertilizing capacity. Animal models showed testicular atrophy and reduced libido, but these have not been replicated in humans. Effects on testosterone were inconclusive.

Why it matters

Cannabis use is prominent among males of reproductive age, and many users may be unaware of potential fertility effects. This consolidation of evidence provides a clearer picture of what is and is not established.

The numbers in context

Cannabis associated with reduced sperm count and concentration, abnormal morphology, reduced motility and viability. Luteinizing hormone levels were lowered. Follicle-stimulating hormone unchanged. Testosterone effects inconclusive.

How the study worked

Systematic review of PubMed/MEDLINE literature examining cannabis effects on male fertility, covering human and animal studies.

What this study cannot tell us

Many findings are from animal studies that have not been replicated in humans. Human studies varied in design and cannabis exposure measures. The review did not conduct a meta-analysis.

How to read the evidence

Moderate: systematic review of multiple study types, but many key findings from animal models only.

When this study was published

Published in 2019.

The bigger picture

Male fertility has been declining globally for decades. If cannabis contributes to this trend, it is a modifiable risk factor that men trying to conceive could address.

Questions still open

  • Are the sperm effects reversible with cessation? Does CBD-only use affect fertility differently than THC? What level of cannabis use begins to impact sperm parameters?

Common questions

Does cannabis definitely cause infertility?
The evidence suggests cannabis can negatively affect several sperm parameters, but it does not necessarily cause infertility outright. The effects may depend on frequency and amount of use.
Are the effects reversible?
The review did not conclusively answer this, but some individual studies suggest sperm parameters may improve after cannabis cessation. More research is needed.

Read the original research

Cannabis and Male Fertility: A Systematic Review.

The Journal of urology, 202(4), 674-681

Citation

Payne, Kelly S; Mazur, Daniel J; Hotaling, James M; Pastuszak, Alexander W. (2019). Cannabis and Male Fertility: A Systematic Review.. The Journal of urology, 202(4), 674-681. https://doi.org/10.1097/JU.0000000000000248

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