Q&A: "Does Smoking Weed or Vaping Affect Sperm?"

It’s best to pass on the grass when trying to conceive. Moderate and high cannabis/marijuana use may not only has a negative effect on sperm parameters and reproductive hormone levels, but also increases the chance of pregnancy loss for his partner. Chronic use has also been associated with erectile dysfunction.  

As for vaping — while there is good, definitive data showing cigarette smoking is bad for sperm and egg health, the data on vaping is limited. What we do have suggests a negative impact, so our advice would be to avoid vaping as well.

The truth is, the influence of marijuana use on human fertility has not been well studied and the results are mixed. Though some individual studies show little associate between male marijuana use and fertility, most meta studies (aka. a review of many studies on the topic) show there may be a bigger risk.

Two of the more recent meta-analysis (here and here) concluded that cannabis use during preconception has been associated with decreased semen parameters, erectile dysfunction, abnormal spermatogenesis, and testicular atrophy.

Watch our medical advisor and Stanford Professor Dr. Michael Eisenberg break down these and other concerns with cannabis:

• Pregnancy Loss — One study, for example, found that couples with male partners who used marijuana ≥1 time/week during pre-pregnancy had greater risk of miscarraige than couples with males who did not use marijuana. This higher risk of loss may also be true for couples undergoing fertility treatments like IVF.
  
• Sperm Count — Cannabis use is strongly associated with reductions in sperm count and concentration in animal and human studies. In 20 chronic marijuana users who smoked marijuana at least 4 days per week, those who smoked 10 or more times per week had a significantly lower sperm count than men who smoked 5 to 9 marijuana cigarettes per week. This research suggests the more you use marijuana, the slower your sperm counts might be. A Danish cohort study on marijuana use in 1,215 participants revealed similar changes: Men who reported using marijuana more than once per week had a 28% lower sperm concentration and a 29% lower sperm count than men who had never used marijuana.
  
• High Levels of Testosterone — Marijuana smokers may have higher levels of testosterone, and in fact these levels are comparable to those of cigarette smokers. 

Studies have also reported the presence of cannabinoid receptors in the male reproductive tract (including on sperm), suggesting that the endocannabinoid system plays a role in regulating reproduction. Cannabis acts directly on these receptors, and this may be one mechanism by which it impacts various reproductive outcomes.

What about specific cannabis forms?

The truth is, we just don't have good enough evidence on what forms, and how much, harms male or female fertility. We recommend — as do our advisors who have run some of the largest studies we do have on the topic — avoiding cannabis use in all of its forms in the preconception period.

How long after quitting weed does male fertility improve?

But sperm can bounce back! Since you are always producing sperm (it takes about 2-3 months to create a sperm), it's likely that 2-3 months after you quit, your new sperm will be unimpacted. This timeline might be slightly longer for chronic users, since marijuana lingers in the body and can take a few weeks to leave your system. If you're a casual user, sperm may rebound more quickly.

Will one puff kill all your sperm?

Probably not. Most of the research we have showing harm has been done on people who use cannabis often, or chronically (though how many times a week is meant by these defintions is not consistent).

Toxins from tobacco smoking can potentially affect sperm development and function, with a negative effect on semen parameters. Watch our medical advisor and Stanford Professor Dr. Michael Eisenberg break it down!

The big things correlated to smoking when it comes to men's fertility are:

• Decreased sperm paramters — In a review of 20 of the top studies on the link between smoking and sperm, exposure to cigarette smoking was associated with reduced sperm count, motility, and morphology. There might also be an outsized impact of smoking on sperm for people who already have borderline or low parameters.
  
• DNA damage to sperm — the harmful chemicals from cigarettes causes genetic and epigenetic alternations in male reproductive function. This can lead to more chromosomal abnormalities.
  
• Reduced fertilization rates — in IVF studies like this one, cigarette smoking appears to reduce not only semen quality, but fertilisation and blastocyst formation rates.

People often ask if vaping is a "safer" alternative, and the answer is that we just don't have enough data, espeially in humans, yet. The limited data we do have points to an overall harmful effect on fertility, since many of the chemical components of e-cigarettes are known to have a negative effect on reproduction. Most doctors and scientists would suggest abstaining from vaping if you can. This is because we have no evidence of a safe amount at this point.

How long after quitting smoking does male fertility improve?

Good news — this study in Nature is one of many showing that smoking cessation had a positive effect on sperm concentration, semen volume, and total sperm count.

So, how long should you try to quit before TTC? The answer here is the same as cannabis: since men produce sperm all the time and sperm take about three months to mature, we recommend quitting at least three months before trying for a baby. This will help make sure the sperm is healthy when the baby is conceived.