Marijuana and Male Fertility: Does Weed Lower Sperm Count?

Man smoking a marijuana joint

Does Marijuana Decrease Male Fertility?

While further research is needed on cannabis use and sperm health, the current evidence strongly suggests that marijuana does have a negative impact on male fertility. This conclusion is supported by a good deal of evidence.

Studies have been conducted for many years showing that sperm contain cannabinoid receptors. This suggests that cannabis may be able to cause disruptions in sperm function.

Research now shows that marijuana’s impact can effect sperm health in a number of ways, including:

  • Lowering sperm count
  • Decreasing sperm concentration
  • Altered sperm morphology and motility (shape and movement)
  • Reduction in sperm viability, or lifespan
  • Hormonal changes
  • Decrease in sexual drive and performance

Additionally, several of these effects can last for several weeks or even months after stopping marijuana use.

How Does Marijuana Affect Sperm Count?

Research indicates that marijuana use lowers sperm count. Studies have also shown that marijuana use is associated with a reduction in sperm concentration.

Men who smoke marijuana more often than once per week experience a nearly 30% decrease in sperm count and concentration. This effect has been demonstrated to persist for up to six weeks, even after the marijuana use is stopped.

For example, one study involving over 1,200 young men between the ages of 18 and 28 found that smoking marijuana more than once per week was linked with a 28% lower sperm concentration and a 29% lower sperm count than non-using participants.

Men who used marijuana more often than once per week along with other recreational drugs had a 52% lower sperm concentration and a 55% lower sperm count than non-using participants.

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How Does Cannabis Affect Sperm Motility?

Sperm motility refers to the sperm’s ability to swim. Sperm motility is important to fertilization because the sperm has to be able to move properly in order to reach the egg. Both recreational and medicinal marijuana use are associated with a decrease in sperm motility.

According to one review, there a large amount of evidence to indicate that marijuana impairs sperm motility. However, the studies cited in the review were with animals, so more testing with human participants is necessary for more accurate findings.

How Does Cannabis Affect Sperm Morphology?

Sperm morphology refers to the size and shape of the sperm cell. The shape of the sperm, with its round head and long tail, allows it to make its way to the egg in order to fertilize it. It can be difficult for pregnancy to occur if the sperm cells are abnormally shaped.

Research from the UK and the US has shown that men who used cannabis three months prior to providing a semen sample had abnormal sperm morphology. Even younger men, those who were age 30 or less, experience this phenomenon.

One research review examined nearly 50 different studies involving marijuana and fertility. It concluded that studies involving both animals and humans suggest that marijuana may cause abnormal sperm morphology, which can negatively impact fertility.

Does Marijuana Affect Sperm DNA?

Although there hasn’t been enough research, it is possible that marijuana could affect the genetic makeup of sperm cells.

A study from Duke University reviewed experiments with rats and study involving 24 men. The researchers discovered that THC can alter a process known as DNA methylation. This could potentially cause autism, according to the researchers.

Other Side Effects

Hormonal Changes

Not only have the effects on sperm count, quality and viability been shown, but cannabis also has an impact on the production of reproductive hormones, like luteinizing hormone (LH).

Because it regulates testosterone levels, this hormone is a key component necessary for fertility. Studies show that testosterone levels in men are affected more by recent use as opposed to the frequency of use.

Testicular Atrophy

An additional adverse effect that men may experience from frequent long-term marijuana use is testicular atrophy. This condition causes the testes to shrink in size, and may even result in the loss of function.

This can happen because of damage that occurs to the tubes where sperm production take place (seminiferous tubules). Although this condition is often reversible, it is something to be aware of when assessing male fertility in men who may have used marijuana consistently for a long period of time.

Erectile Dysfunction

Finally, there is compelling evidence to suggest that marijuana use can also lead to ED, or erectile dysfunction. Although it has long been considered an aphrodisiac in many cultures, current studies show that marijuana actually has an adverse effect on sexual performance. .

For example, one study showed that 78% of the male participants who experienced ED used cannabis on a regular basis, while only 3% of the men with ED did not. Researchers believe that marijuana use promotes ED because of damage that occurs to the endothelial cells. The endothelial cells are cells that are located on the inside of blood vessels that help to keep an erection.

How Long After Quitting Smoking Weed Will Sperm Improve?

You may be wondering if smoking cannabis could be affecting you or your partner’s ability conceive. If so, how long does it take for fertility to improve after quitting smoking marijuana?

A recent study found that those men who had stopped using marijuana for 77 consecutive days no longer produced sperm that exhibited the negative effects seen while they were still using it.

While the average time it takes for sperm to develop is 74 days, it can take up to 90 days for sperm to fully mature. Therefore, quitting weed for 3 months prior to trying to conceive will greatly improve sperm quality and your odds for pregnancy.


Research suggests that cannabis use can potentially decrease male fertility. Much of the available studies highlight the need that more research is necessary.

It is important to understand the potential effects of marijuana on fertility if you plan on having children in the near future. However, this doesn’t mean that regular users are infertile.

It might be a smart idea to consult a doctor if you use cannabis regularly before you try to conceive. You can talk to your provider about lifestyle changes that can be made to increase fertility.

In the meantime, men who are concerned about their fertility may want to cut back on their marijuana use.

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