Does Marijuana Lower Testosterone? A Male Infertility Expert Explains

Trying to unwind at the end of a long day? Or maybe you want a little motivation boost during your workout, or some help getting in the mood on date night? For all of these, research suggests that a little weed can help — and that it’s safe, especially compared to other mood-altering substances. But safe doesn’t mean “without any negative health effects.” Some medical professionals are concerned about the potential effect of marijuana on men’s testosterone and reproductive health. But what that means for your weed habit is complicated — and depends on your relationship to cannabis, your health, and your goals.

First things first: What does research say about the connection between marijuana and testosterone? Right now, the evidence is murky. Much of it is dated, or was conducted in animals, or is based on participants’ account of their marijuana use. In short, there’s very little tightly controlled science out there, says Alexander Pastuszak, M.D., Ph.D., a urologist specializing in male infertility at the University of Utah Health. “We’re working with pretty limited data,” he says.

Some of the first studies that looked into the association appeared to demonstrate a clear negative effect of marijuana on testosterone. In the 1970s, researchers compared 20 regular marijuana smokers to men who had never smoked. On average, testosterone levels in the smokers were more than 30% lower than the non-smokers — but were still within a normal range.

Recent research is more ambiguous. In a 2017 study published in the journal Andrology, scientists followed more than 1,500 young men and found no difference in average testosterone between men who smoked marijuana frequently and those who didn’t smoke at all. However, cannabis actually appeared to spike testosterone levels in men who had recently smoked, even though it didn’t have a long-term effect.

Still, the data we have is enough to raise concern for doctors studying men’s hormonal health and fertility. “They certainly suggest that there may be a negative effect,” Pastuszak says. Particularly convincing to him was a 2022 study on macaques in which scientists fed the primates edible THC, which allowed them to standardize what the study subjects were taking and avoid unreliable self-report data. The study, published in the journal Fertility and Sterility, found a small decrease in testosterone levels and a more than 50% decrease in testicular size — a sign that something was off in the stoner primates, hormonally.

Some research also indicates a link between weed and other parts of the male reproductive system, including testicle size, sperm health, and other hormone levels, some of which play a direct role in testosterone production, Pastuszak says. However, similar to the research on cannabis and testosterone, the evidence here is wishy-washy. “Right now, the conversation among clinicians is we’re not really sure, but there are definitely some studies” finding a negative effect on testosterone and fertility, Pastuszak says.

So, given all this uncertainty, should you be smoking less weed? Pastuszak says maybe, if you’re having symptoms of low testosterone — which include fatigue, muscle weakness, low libido, and more — or are trying to conceive.

Although the research we have on the connection between cannabis and testosterone is far from conclusive, cutting down on cannabis isn’t going to hurt you — and there’s just enough evidence to suggest it might help. Of course, it’s not easy, or even necessary, to cut out cannabis cold turkey. “Every patient has their own perspective. Some will be like ‘no problem.’ Some will be like ‘oh, heck no,’” Pastuszak says.

If you’re part of the “no problem” crowd, quitting cannabis would be Pastuszak’s recommendation. But if weed is an important part of your quality of life, think about switching to edibles rather than smoking weed — because in terms of testosterone and hormonal health, “there’s a negative impact of smoking anything,” he adds. “If you want to optimize your health, you probably want to cut down.”