In women, a high blood level of prolactin often causes hypoestrogenism with anovulatory infertility and a decrease in menstruation. In some women, menstruation may disappear altogether (amenorrhea). In others, mensturation may become irregular or menstrual flow may change. Women who are not pregnant or nursing may begin producing breast milk. Some women may experience a loss of libido (interest in sex). Intercourse may become painful because of vaginal dryness.

In men, the most common symptoms of prolactinoma are impotence, decreased libido, erectile dysfunction, and infertility. Because men have no reliable indicator such as menstruation to signal a problem, many men with hyperprolactinemia being caused by an adenoma may delay going to the doctor until they have headaches or eye problems caused by the enlarged pituitary pressing against nearby eye nerves. They may not recognize a gradual loss of sexual function or libido. Only after treatment do some men realize they had a problem with sexual function.

Because of hypoestrogenism, hyperprolactinaemia can lead to osteoporosis.