What should you know about prolactin and irregular periods?

Prolactin is a hormone involved in breast milk production. When levels are higher than expected outside pregnancy or breastfeeding, it can interfere with the signals between the brain and ovaries. Ovulation may become infrequent or stop, leading to cycles that are widely spaced, unpredictable, or absent. Breast discharge, reduced fertility, headaches, or vision changes can provide additional clues, although some people have no extra symptoms.

Irregular periods have several possible explanations. Anovulation, polycystic ovary syndrome, perimenopause, and premature ovarian insufficiency can each affect cycle timing, so prolactin is only one part of the assessment.

Arrange a clinical review if cycle changes persist or pregnancy is possible. A clinician may repeat a prolactin blood test under suitable conditions, review medicines and symptoms, and check related hormones. Further evaluation is guided by the result and examination rather than by the cycle pattern alone.

Keep a record of bleeding dates, breast discharge, headaches, medicines, and breastfeeding. Do not start or stop prescribed treatment without advice. Hormonal contraception such as the Combined Pill and medicines such as Metformin for PCOS may be considered for particular situations, not as treatment for every cause.

Seek urgent assessment for a sudden severe headache, new vision loss or double vision, fainting, or severe pelvic pain. Contact a clinician soon for missed periods with breast discharge outside breastfeeding, persistent headaches, or irregular bleeding with symptoms of pregnancy or anaemia.

Ask whether your medicines or symptoms could raise prolactin, whether the test should be repeated, and which examinations are appropriate if the level remains high.