Prolactin, a globular protein secreted by the pituitary gland, is a type of sex hormone and is doubly regulated by the hypothalamus. Under physiological conditions, the hypothalamus secretes dopamine to inhibit the secretion of prolactin, while the hypothalamus secretes thyrotropin-releasing hormone and pentraxin to stimulate the secretion of prolactin. Prolactin secretion can also fluctuate under normal conditions, for example, strenuous exercise, nipple stimulation, and sexual intercourse can raise prolactin. Some medications can affect dopamine secretion and thus prolactin levels, such as phenothiazines, tricyclic antidepressants, antipsychotic drugs such as monoamine oxidase inhibitors, and gastrointestinal drugs such as metoclopramide and domperidone. In addition, commonly used blood pressure lowering drugs such as verapamil and reserpine, and angiotensin-converting enzyme inhibitors such as enalapril can also promote the release of prolactin. There are also pathological factors that can produce hyperprolactinemia, such as pituitary prolactinomas. Non-prolactinomas of the pituitary gland can also stimulate secretion of prolactin from pituitary lactating cells, as in some patients with acromegaly who also have hyperprolactinemia. In hypothyroidism, excessive secretion of thyroid stimulating hormones can also lead to hyperprolactinemia. There are also patients with liver disease who have high prolactin levels due to impaired inactivation and metabolism of prolactin. Prolactin in men can affect male libido and sexual function, and also has an effect on the spermatogenesis process. Therefore, hyperprolactinemia can affect male reproduction, depending on the etiology of prolactin, the degree of elevation, and the duration of prolactin. The mechanism of this effect may be interference with the pulsatile release of secondary hypogonadotropic hormones, reducing the synthesis of gonadotropins and sex hormones. Hyperprolactin can also directly inhibit gonadal synthesis of sex hormones. The clinical manifestations of hyperprolactinemia are mainly sexual dysfunction, such as low libido, erectile dysfunction and retrograde ejaculation, resulting in the inability of men to deliver sperm into the female reproductive tract. In addition, some patients show spermatogenic dysfunction, few sperm or even no sperm, softened testicular texture or mild atrophy. Testicular biopsy in these patients may show thickening or fibrosis of the boundary membrane of the varicocele, and hypospermatogenic function or blockage. The treatment of hyperprolactinemia should first identify the cause and discontinue drugs that affect prolactin levels. Patients with asymptomatic hyperprolactinemia can have their prolactin levels monitored regularly, while those with symptoms should be treated with medications. Commonly used drugs are dopamine agonists, and bromocriptine is the clinical drug of choice. Bromocriptine inhibits the secretion of prolactin and does not affect the secretion of other hormones by the pituitary gland. Since bromocriptine can cause hypotension, it should be started at a small dose (1.25 mg per day), given at night before bedtime, and gradually increased in the morning and midday until the blood prolactin stabilizes at normal levels. After satisfactory efficacy is achieved, the dose of bromocriptine can be gradually reduced to the minimum effective dose for long-term maintenance treatment. Patients with pituitary tumors may be seen in neurosurgery and, if necessary, treated surgically. Men with pituitary lactinomas should be treated with a combination of surgery and medication. After surgical or pharmacological treatment, the patient’s sex hormone level and sexual function will return to normal in about 2 months.