This common habit could be quietly hurting men’s fertility, experts warn

As the Trump administration moves to loosen federal restrictions on drugs — including a new step to ease regulations on state-licensed medical marijuana — questions are growing about cannabis use and its broader health effects.

Among them is a lesser discussed concern: men’s fertility.

During National Infertility Awareness Week, experts are drawing attention to the potential negative impact of both recreational and medical cannabis on male reproductive health.

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Cannabis use has been associated with changes in reproductive health for both males and females, though human evidence remains mixed.

"This is especially disheartening when men and women are actively trying to conceive and start a family," Dr. Alta DeRoo, chief medical officer of the Hazelden Betty Ford Foundation in Minnesota, told Fox News Digital.

A 2025 Harvard-linked study involving women undergoing fertility treatment revealed twice as many miscarriages among those using cannabis compared to non-users.

It’s a common misconception, however, that fertility issues are always due to an issue with the woman. Male infertility is more common than many think, according to Stephanie Seminar, MD, chief of the Reproductive Endocrine Unit at Massachusetts General Hospital, a founding member of Mass General Brigham in Boston, Massachusetts.

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"Many individuals think infertility is a woman’s problem, [but] male infertility is common and under-evaluated," Seminar told Fox News Digital.

Out of the 10% to 15% of couples worldwide who experience infertility, male factors cause or contribute to approximately 45% of those cases, data shows.

Having normal sexual drive and performance does not mean that a man has normal fertility, Seminar noted.

An evaluation of male infertility goes beyond semen analysis, examining factors like sexual dysfunction, toxin exposure, tobacco/cannabis use, childhood illnesses and past testosterone use, according to medical experts.

Cannabis use, particularly when heavy and chronic, can have negative effects on male fertility, Seminar cautioned. Those can include changes in reproductive hormones and semen parameters, including decreased sperm counts or mobility.

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Cannabis can also impact sperm quality, the doctor said. "The sperm count or volume can be lower, and those sperm produced may be malformed and unable to swim effectively," the doctor said.

Research supports this decline – a 2019 review published in The Journal of Urology found associations between cannabis use, especially the smoked form, and reduced semen quality.

Another study of 1,215 healthy young Danish men, published in the American Journal of Epidemiology, found that smoking cannabis more than once per week was associated with a 28% lower sperm concentration and 29% lower total sperm count.

Combining marijuana with other recreational drugs more than once a week reduced sperm concentration and count even higher – by 52% and 55%, respectively.

The human body produces its own natural endocannabinoids to regulate vital functions like fertility, as described in a Nature Reviews Urology analysis.

Cannabis mimics these molecules with its two main compounds: cannabidiol (CBD) and THC (tetrahydrocannabinol), which interact directly with the body’s endocannabinoid system. 

While THC can relieve pain or stimulate appetite, it also triggers the "high" that often leads to adverse side effects, like anxiety or paranoia, which have been widely documented in cannabinoid research.

When cannabis is consumed, external cannabinoids enter the body and bind to the same receptors as natural endocannabinoids, which may impair sperm quality and reproductive function, according to previous studies.

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Cannabis may interfere with the brain’s regulation of reproductive hormones, with some research suggesting it can alter levels of FSH (follicle-stimulating hormone) and LH (luteinizing hormone), which signal the testes to support sperm production.

This hormonal suppression could contribute to fertility challenges in some cases, though researchers noted that human evidence remains mixed and continues to be studied.

Men planning to conceive should stop using cannabis, experts recommend, as it can significantly impair sperm quality, with higher usage correlating to worse outcomes.

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Any negative effects may be reversible, as fertility can be improved when couples stop cannabis use, DeRoo noted.

Experts recommend discontinuing cannabis use at least three months prior to conceiving to allow the body to generate a full cycle of healthy sperm.

The American Society for Reproductive Medicine also encourages couples trying to conceive to avoid recreational drugs to maximize their chances of a healthy birth.

"Stopping the use of cannabis improves other areas of health in a person’s life, and conception or pregnancy can be a strong motivator for abstinence," DeRoo added.

In 2021, nearly one in five Americans (52.5 million people) used cannabis, making it the most common federally illegal drug in the country, per CDC data.

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Statistics show that about 30% of users may develop cannabis use disorder at some point, which adversely impacts their daily activities.

Recreational cannabis is legal in roughly half of U.S. states, while medical marijuana is legal in a large majority (well over 30 states), according to the CDC. A small number of states still prohibit most forms of cannabis use.