Prolactin

Prolactin supports milk production, but a raised level outside pregnancy and breastfeeding can suppress ovulation and cause irregular or absent periods, and occasionally milky nipple discharge. Causes include stress at the time of the blood draw, some medicines, an underactive thyroid and benign pituitary tumours. Treatment of the cause often restores ovulation.

Also known as: high prolactin, hyperprolactinaemia

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.