Background: While cannabis is the most widely used recreational drug in the world, the effects of phytocannabinoids on semen parameters and reproductive hormones remain controversial. Cannabinoid receptors are activated by these compounds at each level of the hypothalamus-pituitary-gonadotropic axis.

Objectives: To assess the impact of the consumption of Δ-9-tetrahydrocannabinol and cannabidiol on semen parameters, as well as on male reproductive hormone and endocannabinoid levels, in a cohort of young Swiss men.

Materials and methods: The individuals in a Swiss cohort were divided according to their cannabis consumption. In the cannabis user group, we determined the delay between the last intake of cannabis and sample collection, the chronicity of use and the presence of cannabidiol in the consumed product. Urinary Δ-9-tetrahydrocannabinol metabolites were quantified via gas chromatography-mass spectrometry. Blood phytocannabinoids, endocannabinoids and male steroids were determined via liquid chromatography-mass spectrometry/mass spectrometry, and other hypothalamus-pituitary-gonadotropic axis hormones were determined via immunoassays. Semen parameters such as sperm concentration and motility were recorded using computer-assisted sperm analysis.

Results: Anandamide, N-palmitoyl ethanolamide, androgens, estradiol and sex hormone binding globulin levels were all higher in cannabis users, particularly in chronic, recent and cannabidiol-positive consumers. Gonadotropin levels were not significantly different in these user subpopulations, whereas prolactin and albumin concentrations were lower. In addition, cannabis users had a more basic semen pH and a higher percentage of spermatozoa with progressive motility. However, the two latter observations seem to be related to a shorter period of sexual abstinence in this group rather than to the use of cannabis.

Conclusions: Because both cannabidiol and Δ-9-tetrahydrocannabinol are frequently used by men of reproductive age, it is highly relevant to elucidate the potential effects they may have on human reproductive health. This study demonstrates that the mode of cannabis consumption must be considered when evaluating the effect of cannabis on semen quality.