Starting a Family

Marijuana Does Affect Men's Sperm, And Here's How

If you've been confused by the facts surrounding the impact smoking weed can have on a man's sperm count, you're not alone. Here's what experts are saying.

By Emily Shiffer

Published on March 8, 2019

Marijuana use in America is clearly booming—several states have made its use legal, and more states are projected to make it legal soon. And it is estimated that 16.5% of adults in the U.S. use marijuana.

With its popularity gaining, research on marijuana's health benefits and risks has become robust. And when it comes to fertility, it's become a hotly debated (and studied) topic to learn about its impacts on sperm and sperm health. Is marijuana use good or bad for sperm?

First, you should understand how marijuana effects sperm.

"Tetrahydrocannabinol (THC), the active compound of marijuana, binds to receptors in many different glands and tissues that are involved in sperm production," says Matthias Hofer, MD, a urologist at Northwestern Memorial Hospital. "These receptors are found in the hypothalamus and pituitary gland, decreasing hormone production necessary for sperm production."

When it comes to research, most studies have concluded that marijuana is not good for sperm.

"There are many lab studies showing negative effects of marijuana on sperm. There are surprisingly few human trials, but they all demonstrate that cannabis use reduces sperm concentration, sperm motility (ability to swim), or both," says Doron Stember, MD, assistant professor of urology at the Icahn School at Mount Sinai.

Experimental laboratory studies showed that THC decreased the number of mobile sperm by up to 20%, and also inhibited the ability to fertilize an egg, adds Dr. Hofer. Men who used marijuana more than once a week had a nearly 30% decrease in sperm count compared to those men not using THC, and a 5% decrease compared to those with less frequent use.

Besides the impact on sperm count and mobility, it was also found to fundamentally change the sperm itself.

And a study published in the journal Epigenetics found that marijuana actually mutates DNA in sperm.

Plus, cannabis use has also been found to decrease men's ability to orgasm.

If the evidence seems stacked against marijuana use, there have also been some studies that negate marijuana's negative effects on fertility.

And a 2019 study published in the journal Human Reproduction found that men who reported using cannabis had "significantly higher" sperm counts than men who reported never using cannabis.

One study also showed that cannabis use was associated with—but did not necessarily cause—higher testosterone levels.

While this can complicate a finite answer, doctors do believe more research needs to be done.

"While the scientific evidence that THC negatively impacts fertility at many levels is abundant, it should be noted that some of these studies are limited by low patient numbers and that a subset of studies found contradictory results," says Dr. Hofer. "Clinical trials, the highest quality study type producing the most reliable results, have not yet been performed and would provide further clarification."

But if you do smoke marijuana and have difficulty conceiving, it may not be the sole root cause of your infertility issues.

"Fertility can be affected by many factors and THC is just one of them," says Dr. Hofer. "Although there is ample evidence that sperm count and quality is affected by THC, if considering fertility overall (lower sperm count may still be sufficient for conception) it appears that there is no difference in the probability of couples getting pregnant among those using marijuana compared to those that did not, according to a recent study."

Another note: the method of marijuana consumption (i.e. smoking vs. edibles), is likely has the same impact on sperm.

"Resorption of THC occurs after inhalation and also after ingestion and the effect on sperm can be assumed to be similar," says Dr. Hofer.

However, adds Dr. Stember, "No studies comparing the effects of smoking, vaping, or eating marijuana have been performed."

So should men stop using marijuana if they're trying to conceive with their partner?

While the research has gone both ways about marijuana's impact on sperm, doctors do not recommend men using marijuana.

"Based on the current evidence, it may be advisable to stop THC intake when conception is planned, even if the sperm count would likely be sufficient in absence of other factors associated with decreased sperm count," says Dr. Hofer.

And Dr. Stember agrees.

"Men who are worried about their fertility potential should stop or reduce their marijuana use. The impact of marijuana on sperm seems to be dose-dependent. The more marijuana used, the more likely a man is to have sperm problems," says Dr. Stember.

RELATED: Factors That Affect Fertility

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