Prolactin is a hormone made by the pituitary gland, a pea-sized organ tucked underneath the brain. Its main job is to prepare the breast for milk and to maintain milk production once a baby is born. In pregnancy and breastfeeding, prolactin levels rise many-fold and that is entirely normal and expected.

Outside of pregnancy and breastfeeding, prolactin should stay low — usually below 25 nanograms per millilitre (ng/mL) on a fasting morning blood test. When the level is higher than this without a baby on the way, doctors call it hyperprolactinemia and look for a reason.

Prolactin matters for fertility because it speaks directly to the part of the brain that controls ovulation. When prolactin is high, the brain reduces the signal that tells the ovaries to release an egg each month — so periods become irregular, ovulation stops, and pregnancy does not happen. The good news is that this whole chain reverses once prolactin is brought back to normal.

A single high prolactin reading is not the whole story. Stress, a recent breast exam, recent sex, a heavy meal, exercise just before the test, or a poor night's sleep can all push prolactin up briefly. That is why a borderline result is usually repeated, with a calm fasting morning sample and no breast stimulation in the hour beforehand.

As a rough guide: values below 25 ng/mL are normal for non-pregnant women, 25 to 50 ng/mL is mildly elevated and often medication or stress related, 50 to 100 ng/mL is moderately elevated and needs a careful workup, and values above 100 ng/mL strongly suggest a prolactinoma and usually prompt an MRI of the pituitary. In pregnancy, levels up to several hundred ng/mL are normal and need no treatment.

If your prolactin comes back high, the next questions are simple: Is it really high (repeat the test), what is causing it (medications, thyroid, tumour, lifestyle), and is it affecting your periods or fertility?

• A small benign tumour of the pituitary gland called a prolactinoma — this accounts for roughly half of all confirmed cases of hyperprolactinemia, and the great majority are tiny micro-adenomas under 10 millimetres.
• Medications: antipsychotics (especially risperidone), domperidone (very common in India for nausea or to boost breast milk), metoclopramide, certain antidepressants in the SSRI family, opioid painkillers, and some hormone preparations.
• Hypothyroidism — when the thyroid is underactive and TSH is high, prolactin often rises along with it, and simply treating the thyroid brings prolactin back to normal.
• Stress and pain — usually a small, transient rise that disappears once the trigger settles; this is one reason a single borderline reading is repeated rather than acted on immediately.
• Chest wall stimulation — nipple piercings, breast surgery, herpes zoster on the chest wall, or repeated chest trauma can all signal the brain to release prolactin.
• Polycystic ovary syndrome (PCOS) is sometimes associated with mildly raised prolactin, though usually not the high values seen with a prolactinoma.
• Chronic kidney or liver disease can raise prolactin because the body clears it more slowly.
• Idiopathic — sometimes the workup finds no clear cause, the level is mildly elevated, and the doctor either monitors or treats based on symptoms.

The most common signs are reproductive: periods that become irregular, very light, or stop altogether (oligomenorrhea or amenorrhea); milk-like discharge from one or both breasts even though you are not pregnant or breastfeeding (galactorrhea); difficulty getting pregnant despite regular sex; and a noticeable drop in sex drive. Not every woman has every symptom — some discover their high prolactin only on a routine fertility workup.

When the cause is a larger pituitary tumour, additional symptoms can appear: persistent headaches, especially behind the eyes or at the front of the head, and changes in side vision because the growing tumour presses on the optic nerves above. These are uncommon and are signals to seek care urgently rather than wait.

If your periods have been irregular for several months and there is no obvious cause, what irregular periods can mean walks through how to think about the pattern; prolactin is one of the standard tests in that workup.

The basic test is a simple blood draw for serum prolactin. The sample is best taken in the morning, after an overnight fast, without any breast examination, intercourse or intense exercise in the hour before. A single high value is not enough — most clinicians repeat a borderline result on a different day to rule out a stress spike. Typical cost in Indian private labs (Thyrocare, Metropolis, SRL, Lal PathLabs) is ₹400 to ₹1000 for prolactin.

A thyroid test (TSH) is almost always added, because an underactive thyroid is a common and easily treatable cause of raised prolactin. Typical TSH cost is ₹250 to ₹500. Many clinicians order both together as a small panel.

If the prolactin value is high — usually above 100 ng/mL, or persistently elevated despite no medication cause — an MRI of the pituitary is the next step, to look for a micro- or macro-adenoma. MRI cost in India ranges from ₹5000 to ₹15,000 depending on city, machine and contrast use. Government and trust hospitals offer the same test at significantly lower cost, sometimes free.

For most women, treatment is a tablet, not surgery. The first-line medication in India is cabergoline (brand names Caberlin, Dostinex and others), usually started at 0.25 mg twice a week and titrated up over a few weeks depending on the response. It works by mimicking dopamine and switching off prolactin production at the source. Monthly cost is typically ₹500 to ₹1500. The older medication bromocriptine (Parlodel) is cheaper at around ₹200 to ₹500 a month, but causes more nausea and dizziness, so cabergoline is usually preferred when affordable.

Side effects in the first weeks are usually mild — nausea, light-headedness on standing, a touch of constipation or stuffy nose. Starting at a low dose with food and increasing slowly almost always settles this. If a particular cause is identified, treating that cause is the priority: stopping or switching a triggering medication (always with the prescribing doctor's involvement — never stop psychiatric medication on your own), or treating an underactive thyroid often brings prolactin back to normal without needing cabergoline at all.

Surgery — a trans-sphenoidal operation that removes the tumour through the nose — is reserved for the small number of cases where medication does not work, the tumour is very large, or vision is being threatened. For most women, the journey is from a blood test to a tablet to a return of regular periods within a few months.

Prolactin and fertility are tightly linked. High prolactin suppresses the brain's release of GnRH, which in turn dampens the signals that drive ovulation. With no egg released each month, pregnancy cannot happen. This is one reason hyperprolactinemia is part of the routine workup for couples who have been trying for a year or more without success, and shows up in roughly a third of female infertility evaluations.

The encouraging part is how quickly this reverses. Once cabergoline is started, prolactin usually drops within 2 to 4 weeks, periods often return within 4 to 8 weeks, and ovulation resumes in roughly 80 percent of women within 8 to 12 weeks. Many couples then conceive in the months that follow — sometimes very quickly, especially if there are no other fertility factors at play.

If you are wondering whether your body is ready, is my body ready to conceive is a calm starting place that includes prolactin alongside the other hormonal checks worth doing before active TTC.

Several medications widely used in India can raise prolactin without anyone connecting the dots. Domperidone (Domstal, Domperi, Vomistop) is sold for nausea, indigestion and reflux, and is sometimes prescribed informally to new mothers to boost milk supply. Used for a few days it is usually fine, but longer courses can quietly push prolactin up.

Antipsychotic medicines — used in conditions such as schizophrenia, bipolar disorder and severe anxiety — are another important group. Risperidone, haloperidol and several others raise prolactin as part of how they work, and this is one of the most common reasons a young Indian woman on psychiatric medication develops irregular periods or milk discharge.

Other contributors include metoclopramide (Perinorm) for nausea, certain SSRIs (the antidepressant family that includes sertraline, fluoxetine and others), opioid painkillers used after surgery or for chronic pain, and oestrogen-based hormones. The key principle is that you should never stop a psychiatric or seizure medication on your own — instead, take the prolactin result to both the gynaecologist and the prescribing doctor and let them decide whether to switch the drug, add cabergoline, or simply monitor.

The word tumour is alarming, but a prolactinoma is almost always a small, benign, slow-growing collection of cells inside the pituitary gland — not a cancer. Most are micro-adenomas under 10 millimetres in size and many never grow further. A smaller number are macro-adenomas (over 10 millimetres), which can press on nearby structures and cause headaches or vision changes.

Cabergoline is remarkably effective even when a tumour is present. In most women, the tablet not only brings prolactin back to normal but also shrinks the tumour over months to years. A repeat MRI is usually arranged after a year or so to confirm the shrinkage. Many women eventually wean off cabergoline once the tumour has shrunk and prolactin has stayed normal for an extended period — so it is not necessarily a lifelong medication.

Macro-adenomas are managed more carefully, with closer monitoring of vision and earlier consideration of higher doses or surgery if there is any threat to the optic nerves. In either case, the team is usually a gynaecologist plus an endocrinologist, and sometimes a neurosurgeon if the tumour is large.

Pregnancy itself raises prolactin to high levels — sometimes several hundred ng/mL — and this is entirely normal because the body is preparing the breast for milk. A high prolactin in a confirmed pregnancy is not hyperprolactinemia in the disease sense and does not need treatment. The same is true of the early months of breastfeeding.

If you have a known prolactinoma and become pregnant, the standard advice is to discuss next steps with your endocrinologist as soon as you have a positive test. Cabergoline is usually stopped in early pregnancy in women with a micro-adenoma, because the medication is no longer needed and the tumour rarely grows in pregnancy. Women with a macro-adenoma may continue medication and have closer monitoring throughout pregnancy.

After birth, decisions about restarting cabergoline are made in line with your breastfeeding plans — cabergoline can dry up milk, so most women on cabergoline who want to breastfeed wait until weaning before restarting. None of this needs to be figured out alone; a gynaecologist working with an endocrinologist will guide the timing.

Myth: any milk-like discharge from the nipple means you must be secretly pregnant. Fact: galactorrhea is very often hormonal and not a sign of pregnancy at all. A simple urine pregnancy test plus a prolactin and TSH blood test will sort this out in a day.

Myth: stress alone causes permanent high prolactin. Fact: stress can push prolactin up briefly, but a true, sustained high needs a real cause — medication, thyroid, prolactinoma or another medical reason — which is why your doctor will repeat the test and look further rather than blame stress.

Myth: once you start cabergoline, you are on it for life. Fact: many women wean off cabergoline successfully after the tumour has shrunk and prolactin has stayed normal for a year or two, especially with micro-adenomas. The plan is reviewed with your endocrinologist and is rarely a forever decision.

If your high prolactin sits alongside PCOS-type symptoms, PCOS isn't your fault is worth reading — the two conditions can overlap and benefit from being looked at together. And if you have already had a child and are now struggling to conceive again, secondary infertility in India covers the broader workup that includes prolactin.