In clinical practice, we often encounter patients with fertility requirements who are also taking medications for other diseases. So, does taking medication have an effect on sperm? Under normal circumstances, there is a protective layer between the testicular tissue and the blood supplying nutrients to the testes, which is medically known as the blood-testis barrier, and this barrier can prevent certain substances in the blood from entering the testes. However, a number of drugs can pass through the blood-testis barrier, thus affecting testicular function, interfering with sperm formation and affecting healthy sperm-egg union in two ways. Drugs affect male fertility in four ways: first, they act directly on the male gonads, affecting the function of the sperm-producing spermatogenic cells of the testes and a type of cell in the testes called Leydig cells; second, they act on the hypothalamic-pituitary-gonadal axis, affecting the normal secretion of hormones in the body leading to changes in gonadotropin and testosterone levels, ultimately affecting fertility; third, they impair ejaculatory function and erectile function of the penis, making it impossible for semen to enter the spouse, thus causing sperm disorders; fourthly, it negatively affects male libido, causing a lack of normal sexual life between couples. Specific drugs can be divided into the following categories: i. Chemotherapy drugs: The effect of chemotherapy drugs on fertility is related to the type of chemotherapy drug, the dose and the time of use of the drug. Commonly used chemotherapy drugs that have an impact on fertility are: adriamycin, genomycin, vincristine, nitrogen alkylamine, nitrogen mustard, vincristine sulfate, procarbazine hydrochloride, cisplatin, etoposide, etc. Second, blood pressure drugs: most blood pressure drugs on fertility are through the impairment of sexual function, some diuretics can cause erectile dysfunction by reducing vascular resistance and thus lead to inadequate blood supply to the penis, beta-blocker insulin can affect libido and erectile function. Antiseptic can affect fertility by affecting erectile function and libido as well as the potential effect on semen quality. Calcium channel blockers can inhibit the normal process of fertilization. Hormonal drugs: The use of anti-androgen drugs can also cause fertility problems because they can affect the normal physiological function of androgens in the body (decreased libido and sperm production disorders). An increasing number of athletes abuse anabolic steroids. Heavy use of anabolic androgens can lead to hypogonadism with low gonadotropins. Normal gonadal function can be restored after discontinuation of the drug in most cases. Fourth, other drugs; some of the commonly used drugs such as: neomycin, erythromycin, gentamicin and other antibacterial agents may cause a decrease in semen quality. Immunosuppressants used in organ transplant patients, such as: cyclosporine, can also cause a decrease in sperm density and viability. Colchicine and allopurinol for the treatment of gout also have adverse effects on male fertility. Furacilin, cimetidine, salazosulfadiazine, cocaine, nicotine, and marijuana can impair spermatogenesis. However, spermatogenesis and/or sperm function may return to normal after discontinuation of the drug. Exposure to environmental toxins such as pesticides should also be noted. IV. Other: Some studies have pointed out that interferon, lamivudine, adefovir and other drugs for hepatitis B can significantly reduce the density, vitality and viability of sperm, but adefovir is effective in treating hepatitis B and has the least effect on the quality of sperm in patients, and the best time for fertility in hepatitis B patients is 12 weeks after stopping the drug.