Merck Manual

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What Causes Infertility in Men?

What Causes Infertility in Men?



Reduced sperm production

Increased temperature of the testes

Excessive heat

Disorders that cause a prolonged fever

Hormonal disorders

Hyperprolactinemia (high levels of prolactin, a hormone that stimulates milk production)

Hypothalamic disorders (the hypothalamus is the part of the brain that controls the pituitary gland, which controls testosterone production)

Genetic disorders

Other disorders that cause an abnormality in the sex chromosomes

Disorders of the testes


Injury to the testes

Shrinking of the testes (as can occur when excess alcohol is regularly consumed)

Tumors in the testes


Alcohol, when consumed in large amounts

Anabolic steroids

Androgens (male hormones such as testosterone)

Antiandrogens (drugs that counteract the effects of androgens, such as bicalutamide, cyproterone, and flutamide)

Antimalarial drugs

Aspirin when taken for a long time

Caffeine when consumed in excessive amounts (possibly)

Chlorambucil (a chemotherapy drug)

Cimetidine (used to treat stomach ulcers)

Colchicine (used to treat gout)

Corticosteroids taken by mouth (such as prednisone)

Cotrimoxazole (an antibiotic)

Cyclophosphamide (a chemotherapy drug)

Drugs used to treat malaria

Estrogens taken to treat prostate cancer



Medroxyprogesterone (a synthetic female hormone)

Methotrexate (a drug that suppresses the immune system)

Monoamine oxidase inhibitors (MAOIs—a type of antidepressant)

Nitrofurantoin (an antibiotic)

Opioids (narcotics)

Spironolactone (a diuretic)

Exposure to industrial or environmental toxins

Heavy metals, such as lead

Pesticides (which can have effects similar to those of female hormones or decrease the effects of male hormones)

Phthalates (chemicals used to make plastics more flexible)

Polychlorinated biphenyl compounds (PCBs)

Absence of sperm in semen

Disruption of the sperm’s passage out of the body

Blocked or missing vasa deferentia (tubes from the epididymides to the ejaculatory ducts), usually in men with cystic fibrosis

Missing seminal vesicles (which provide nourishment for sperm)

Blockage of both ejaculatory ducts

Diabetes mellitus

Nervous system dysfunction

Pelvic surgery, such as prostate removal

Blood vessel disorders

Diabetes mellitus

Brain and nerve (neurologic) disorders, such as Alzheimer or Parkinson disease, multiple sclerosis, stroke, and nerve damage due to prostate surgery

Psychologic problems, such as performance anxiety or depression

Certain drugs, such as some antidepressants, certain hormonal drugs, and drugs used to treat high blood pressure (including beta-blockers)

Recreational drugs (such as cocaine, heroin, and amphetamines)

Unknown causes (idiopathic)