Sex is more addicting than illegal drugs

Sex, Drugs & Infertility

Around 300 million male germ cells are sent on their way with each ejaculation, and they have only one goal: to find the egg cell and fertilize it. But only one sperm will reach its destination - or it won't. Because not every man is biologically fertile. According to studies, the consumption of cannabis, speed and co. Could be a reason for the hormonal balance in men being permanently upset and resulting in infertility.

Image: no more lookism /

For once it's only about men. Because their lifestyle sometimes leaves something to be desired. Men drink and smoke more than women and when it comes to illegal drugs, one or the other also likes to let it rip. Even if some men consider themselves invulnerable at a young age, studies show that there could be a rude awakening if the desire to have a child arises later.

What many men do not know: The biological clock is ticking not only with women, but also with men. From around the age of 35, the quality of the semen deteriorates. But fertility can already be impaired in young men. The production of a sufficient number of healthy sperm is crucial for fertility. This process depends on complex hormonal controls that can be disrupted by drugs. This applies to drugs from the chemistry laboratory as well as to "natural" substances such as cannabis.

Male infertility is now common among many unwanted childless couples a problem. An American research team has therefore investigated the question of how illegal drugs can affect male fertility. Carolyn Fronczak and her team have compiled all relevant studies in a review article.

THC curbs testosterone

Because of its widespread use, cannabis is of great importance when it comes to male fertility. In the body, THC, the main active ingredient in cannabis, attaches to the same receptors that are occupied by the body's own substances, the endocannabinoids. It is known that endocannabinoids play an important role in reproduction. Endocannabinoid receptors are found in the testes, among other places, and are involved in controlling sperm production there. There are even receptors for endocannabinoids in the sperm itself.

When you smoke weed, you get THC not only to the brain, but is via the bloodstream also to the testicles transported, where it binds to the corresponding receptors and thus can disrupt the so-called hypothalamus-pituitary-testicular axis. The hypothalamus and the pituitary gland are two structures in the human brain that work together with the testes to regulate the production of the sex hormone testosterone. One guess is that if THC binds to the receptors in the testicles, it could reduce testosterone production. Testosterone plays a central role in sperm production.

In fact, during their research, Fronczak and her team came across studies in which the Testosterone levels in the blood of chronic cannabis users are significantly lower was than in abstinent control persons. In addition, the testosterone level was dependent on the amount consumed: the more the subjects smoked, the less testosterone they had in their blood. The decreased production of testosterone, in turn, presumably had greatly reduced the number of sperm in the stoner's ejaculate. This so-called oligospermia was detected in over a third of the chronic cannabis users examined.

Impaired sperm quality

However, not only does the number of sperm cells decrease, but also their quality. As further studies have shown, THC also restricts the sperm's ability to move. This could be due to the fact that THC promotes so-called programmed cell death (apoptosis). There is then a in the ejaculate large proportion of immobile sperm.

The negative influence of THC may also be exacerbated by its relatively long-term availability in the body. The body's own endocannabinoids are normally made available quickly as needed and broken down again just as quickly. When smoking weed, however, the body is literally flooded with THC. The plant cannabinoid is also stored in adipose tissue and gradually released from there. Such “THC reservoirs” in the testes could overstimulate the cannabinoid receptors there and have the negative consequences described for the quality of the sperm.

Ecstasy & Speed: Damage to DNA

Similar to cannabis, ecstasy and speed also impair the normal activity of the hypothalamic-pituitary-testis axis and thus also the production of testosterone. So far, however, the effects of amphetamines have only been investigated in animal studies. In one experiment, male rats were given ecstasy in an amount that is said to be roughly equivalent to the amount of recreational use in humans. The rats' testosterone levels were then reduced by 50 percent.

More detailed studies of the effects of ecstasy on the testes and the quality of the sperm cells of rats also showed significantly more frequent damage to the genetic material (DNA) contained in the sperm and to the testicular tubules in which the sperm are produced. Unlike THC, however, ecstasy did not lead to reduced mobility or other external abnormalities in the sperm.

Cocaine: degenerate cells

As with amphetamines, most of the knowledge about the effects of cocaine on male fertility comes from animal studies. Rats that were given cocaine for several months in the experiment had about a half the probability of producing offspring compared to their abstinent conspecifics. In order to find out the reasons for these differences, these test animals were also examined in detail after the end of the experiment.

The researchers found degenerate and abnormal cells in the sperm-producing tubules of the test animals treated with cocaine. In both high and low doses, cocaine had acute negative effects on sperm production. High doses of cocaine also impaired the blood supply to the testicles for several hours. This reduced blood flow could also partly explain the negative effects of cocaine on fertility.


In their review article, Fronczak and her team were able to show that a large number of studies have shown a negative influence of drug consumption on sperm production and sperm quality. However, it remains unclear in how many cases substance abuse actually plays a relevant role in existing male infertility. According to the Robert Koch Institute, around 5 to 10 percent of couples in Germany are currently involuntarily childless, and around 3 percent have a long-term unfulfilled desire to have children.

Lana Burkman, a researcher at Buffalo University in the United States, also worked on a study of the effects of cannabis use on male fertility. She points out that smoking weed doesn't necessarily mean infertility. For men who are already on the verge of infertility, cannabis could be the deciding factor in getting them over the infertility threshold.


  • Federal Center for Health Education (2005). When a dream does not come true ... Desire for children and infertility. Brochure (order number 13622001). PDF
  • Fronczak C., Kim, E. & Barqawi, A. (2011). The Insults of Illicit Drug Use on Male Fertility. Journal of Andrology. Published-Ahead-of-Print on July 28, 2011. Summary
  • Federal health reporting. Robert Koch Institute in cooperation with the Federal Statistical Office. Issue 20 (April 2004). Unwanted childlessness. report
  • - Infertility in men and women
  • Pabst, A., Piontek, D., Kraus, L. & Müller, S. (2010). Substance use and substance-related disorders. Results of the epidemiological addiction survey 2009. Sucht, 56 (5), 327-336. items
  • Press release Ruhr University Bochum (March 28, 2003)
  • Press release University at Buffalo (13.10.2003)