What Are the Available Male Contraceptives?

Most people are quite familiar with contraceptive pills—but today, contraceptive pills for men also exist. These male contraceptives generally cause less harm to the body than those used by women. However, very few men actually take them. In essence, male contraceptives work by suppressing sperm production, thereby ensuring that ejaculated semen contains no sperm and preventing conception.

What Are the Available Male Contraceptives?

Animal studies have demonstrated that gossypol acetate—a male contraceptive—damages spermatozoa, spermatocytes, and spermatogonia within the seminiferous tubules of the testes, thereby inhibiting spermatogenesis and resulting in azoospermia (absence of sperm in semen). After short-term administration, fertility in animals is fully restored upon discontinuation. Clinical trials indicate an efficacy rate exceeding 99%. However, approximately 1% of users develop hypokalemic muscular weakness during treatment, which has prevented its widespread clinical adoption.
Contraceptive pills generally refer to oral contraceptives, including both female and male formulations. In practice, oral contraceptives are more commonly used by women. Over two decades of clinical experience reveal variable individual responses: some women prefer this method, while others avoid it altogether.

Male contraceptives exert their effects through the following distinct mechanisms:
　　(1) Long-term, high-dose administration of gonadotropin-releasing hormone (GnRH) induces downregulation of pituitary gonadotropins—follicle-stimulating hormone (FSH) and luteinizing hormone (LH)—thereby suppressing spermatogenesis.
　　(2) Administration of antibodies targeting FSH and LH to block their biological activity. However, since both hormones share an identical alpha subunit—and this same subunit is also present in thyroid-stimulating hormone (TSH)—non-specific antibody binding may lead to unintended side effects if selectivity cannot be ensured.
　　(3) Use of endogenous hormones—for example, testosterone alone or in combination with progestins—to suppress pituitary gonadotropin secretion via negative feedback, thereby inhibiting spermatogenesis. Regular intramuscular injections of testosterone enanthate effectively induce reversible infertility and represent a promising candidate for male contraception.
　　All the above agents interfere with spermatogenesis by suppressing the hypothalamic–pituitary–gonadal (HPG) axis. However, they are costly, inconvenient to administer, and concurrently impair Leydig cell function—leading to reduced testosterone levels, diminished libido, or sexual dysfunction—necessitating further research to resolve these limitations. Although testosterone itself suppresses Leydig cell function, its exogenous replacement preserves sexual function, making it particularly promising for clinical development.
　　(4) Selective inhibitors of spermatogenic epithelium—such as gossypol—were first identified by Chinese researchers for their antifertility properties and have since undergone extensive preclinical and clinical investigation in China. This work has attracted significant international attention. Gossypol is an orally administered male contraceptive that is inexpensive and easy to use, though it does carry certain adverse effects.