While medicines can have an adverse impact on spermatogenesis, this may not always lead to infertility. Research showing links to infertility can be based on animal studies but there is often a lack of human data or the clinical impact may be unclear.²⁰

Examples of drugs having at least a theoretical risk of human male infertility include:^{1,9,10,12,17,20,21,22}

·      sulfasalazine;

·      antidepressants such as SSSRIs;

·      nitrofurantoin in high doses;

·      HIV antiretroviral therapy;

·      lamotrigine;

·      clomipramine;

·      paroxitine;

·      methadone;

·      nifedipine;

·      sirolimus;

·      cannabis;

·      cocaine;

·      androgenic anabolic steroids;

·      amphetamines and MDMA;

·      Tripterygium wilfordii (known as thunder god vine, seven-step vine. or lei gong teng in Chinese herbal medicine).

Medicines linked to RE include alpha blockers (which may be being prescribed for benign prostatic hyperplasia or BPH), SSRIs and some antipsychotics.^15,16

Hormonal agents with data showing an effect on spermatogenesis, quality or semen volume in humans include danazol, dutasteride, finasteride, leuprorelin/leuprolide, nandrolone and testosterone (dose dependent).²⁰

Prostate cancer cells usually rely on testosterone for growth. While not a cure, hormone therapy can suppress testosterone production or block receptors and inhibit cancerous prostate cell proliferation. This can shrink tumours, at least until malignant cells develop ‘resistance’ to such treatments. However, side effects include negative impacts on male characteristics, such as testicle and penis size and function, erections and libido.²³

Chemotherapy and cytotoxic drugs can reduce male fertility temporarily or permanently depending on dose, treatment duration and age. Men may be advised to consider sperm banking before chemotherapy commences.^9,24,25