Prolactinoma: The Commonest Pituitary Tumor, and the One Treated With a Tablet
Last updated September 4, 2026.
Your periods have gone missing and there is milky discharge from your nipples, and now the blood test shows a hormone called prolactin far above normal, and the word pituitary tumor has entered your life. Or you are a man whose libido has quietly left the building, and the same hormone explains it. The word tumor deserves its weight and also its context: prolactinomas are benign, they are the most common hormone-making tumor of the pituitary, and uniquely among pituitary tumors, most of them are treated with a tablet rather than surgery.
What it is and what it does
A prolactinoma is a small benign growth of the pituitary gland that secretes prolactin, the hormone that normally drives milk production after childbirth. Excess prolactin does two things: it can trigger milk discharge from breasts that have no business lactating, and it suppresses the hormones that run the ovaries and testes. That suppression is why the condition presents as missing or irregular periods, infertility, or low libido and erectile problems rather than as anything brain-related. The tumor itself is usually small, called a microadenoma when under a centimeter, and many small ones never grow.
Severe new headache or loss of the outer edges of your vision with a known pituitary tumor: emergency department now. Everything else about this condition is a routine appointment.
Start a free AI doctor consult →How it is found
One blood test for prolactin starts the story, repeated to confirm and checked against medication lists, because common drugs, including several antidepressants, antipsychotics, and anti-nausea medicines, raise prolactin without any tumor at all. When the level is clearly high and medications are not the explanation, an MRI of the pituitary shows the growth and measures it. Very high levels, or a large tumor, also earn a vision test, because a big adenoma can press on the optic nerves crossing just above the gland.
The treatment is usually a tablet, and it usually works
Dopamine agonists, cabergoline taken once or twice a week is the common one, lower prolactin and shrink the tumor in the large majority of patients, often within weeks for the hormone and months for the size. Periods and fertility typically return, milk discharge stops, and in men testosterone recovers. Surgery is reserved for the minority who cannot tolerate or do not respond to the tablets, or whose tumor threatens vision. After a couple of years of normal levels, many patients can trial off the medication under supervision, and a fair share stay in remission.
The warnings and the life questions
Two things get fast attention: new severe headache, and any loss of the outer edges of vision, which together can mean the tumor is pressing on the optic nerves or, rarely, bleeding. Those go to the emergency department. Everything else is a conversation: pregnancy is very much possible once prolactin normalizes, and the team adjusts medication around conception with a plan already written for it. Men are diagnosed later on average, because low libido gets endured rather than investigated, which is why men more often arrive with larger tumors. If you are the man in this story, the blood test that found it was the hard part; the treatment ahead is the easy part.
If you are weighing the risks and benefits of any medicine mentioned here, our overview of how medicines are tested and monitored for safety explains what those conversations are built on.
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Common questions
Will the milk discharge stop?
In most cases, yes, and often within weeks of starting a dopamine agonist, because the discharge is driven directly by the prolactin level. As the level normalizes, the discharge dries up, periods return, and fertility follows. A practical note while you wait: repeated nipple checking and squeezing stimulates more production, so the advice is to notice it and then leave it alone. If discharge continues after prolactin has been normal for months, that is worth re-discussing, because other causes of discharge exist.
Can I still get pregnant?
Yes, and this is one of the happiest treatment stories in endocrinology. High prolactin suppresses ovulation; normalize it and ovulation typically resumes, often within weeks to months of treatment. Many women conceive on cabergoline, and the teams managing this have an established routine: medication is usually stopped once pregnancy is confirmed for small tumors, with specific plans for larger ones. Tell your team before you start trying so the plan is written in advance rather than improvised.
Does a high prolactin always mean a tumor?
No, and this is why the workup has steps. Strenuous exercise, stress, sleep disruption, nipple stimulation, and an underactive thyroid all nudge prolactin up, as do a long list of common medications, including many antidepressants, antipsychotics, and stomach remedies. Levels from those causes are usually modest. Very high levels point strongly to a prolactinoma. The doctor's first move on a raised result is often to repeat it calmly and audit the medication list before any scan is ordered.
Do men really get this?
Yes, and they tend to arrive later with bigger tumors, because the male symptoms, fading libido, erectile problems, sometimes enlarged breast tissue, are endured privately for years before anyone tests a hormone. The treatment works the same way in men: prolactin falls, testosterone recovers, and sexual function usually follows. If you are a man reading this after finally being tested, the delay is the common male pattern, not a personal failure, and the treatment ahead is straightforward.
Will I be on the tablets for life?
Not necessarily. Guidelines support a supervised trial off medication after about two years, if prolactin has stayed normal and the tumor has shrunk on imaging, and a substantial share of patients, roughly a third to a half in studies, remain in remission without it. Others restart when levels creep back, which is a routine event, not a failure. Either way, the medication is well tolerated by most people once the early nausea window passes, so the long-term version of this condition is manageable.
What is the difference between micro and macro, and why does it matter?
A microadenoma is under ten millimeters, a macroadenoma ten or more, and the line changes the management more than the prognosis. Small tumors rarely grow, almost never threaten vision, and are usually treated for their symptoms or even just monitored. Large tumors can press on the optic nerves, which is why they come with vision testing, stricter pregnancy planning, and a lower threshold for surgery if tablets do not shrink them. Both are benign; the size decides how closely the team watches.