Prolactinoma: Complete Guide to the Most Common Pituitary Tumor, Symptoms, Causes, and Treatment

5 days ago

8 min read

Updated: 2 days ago

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

TL;DR

A prolactinoma is a noncancerous tumor of the pituitary gland — the small, bean-shaped gland at the base of the brain — that causes it to overproduce the hormone prolactin. It is the most common type of pituitary tumor that makes hormones. Although it is not life-threatening, it lowers estrogen and testosterone, causing missed or irregular periods and milky breast discharge in females, erectile dysfunction and gynecomastia in males, and infertility or osteoporosis in anyone. Untreated, it can grow large enough to press on the optic nerve (first sign: loss of side vision). It is more common in females, and it is usually treated with medicines that shrink the tumor — surgery is needed only in some cases.

Quick Answer

Prolactinoma is a tumor of the pituitary gland that is not cancer. The tumor causes the pituitary gland to make too much of a hormone called prolactin — a condition called hyperprolactinemia. This lowers the body's levels of the sex hormones estrogen and testosterone, and the tumor itself can press on nearby tissue when it grows large. Prolactinoma is the most common type of pituitary gland tumor that can make hormones. Symptoms are often sex-specific: females typically notice missed or irregular periods first (so symptoms are caught earlier, when tumors are smaller), while males and postmenopausal females tend to notice symptoms later, when tumors are larger. It is more common in females, rare in children, and usually treatable with medicines that shrink the tumor and bring prolactin levels down.

What Is a Prolactinoma?

Prolactinoma is a tumor of the pituitary gland that is not cancer. This tumor causes the pituitary gland to make too much of a hormone called prolactin.

A prolactinoma isn't life-threatening. But it can cause health concerns, including vision problems. Having a prolactinoma also can make it hard to get pregnant. That's because it lowers the body's levels of the sex hormones estrogen and testosterone.

Prolactinoma is the most common type of pituitary gland tumor that can make hormones. The pituitary gland is a small bean-shaped gland at the base of the brain. Although it is small, the pituitary gland has an effect on nearly every part of the body. Its hormones help control important work in the body, such as growth, metabolism, blood pressure, and reproduction.

A prolactinoma often can be treated with medicines to shrink the tumor and bring the prolactin level in the body down. Some people need surgery to remove the tumor.

Symptoms

A prolactinoma might not cause any symptoms. But too much of the hormone prolactin in the blood due to a prolactinoma may lead to symptoms. This condition is called hyperprolactinemia. A large tumor also can put pressure on the tissue around it, causing symptoms too.

Too much prolactin can cause health concerns within the reproductive system — a condition called hypogonadism. Because of that, some of the symptoms of a prolactinoma are specific to females or males.

In females, prolactinoma can cause menstrual periods that are not regular or no menstrual periods, milky discharge from the breasts when a person is not pregnant or breastfeeding, sore breasts, painful sex due to vaginal dryness, and acne and extra body and facial hair.

Female symptom	What it looks like
Irregular or absent periods	Menstrual periods that are not regular or no menstrual periods
Milky breast discharge	Discharge from the breasts when not pregnant or breastfeeding
Sore breasts	Breast tenderness
Painful sex	Due to vaginal dryness
Acne and extra hair	Acne and extra body and facial hair

In males, prolactinoma can cause erectile dysfunction, less body and facial hair, smaller muscles, and larger breasts, called gynecomastia.

Male symptom	What it looks like
Erectile dysfunction	Difficulty achieving or maintaining an erection
Less hair	Less body and facial hair
Smaller muscles	Muscle loss or weakness
Gynecomastia	Larger breasts

In anyone, prolactinoma can cause difficulty getting pregnant (infertility), weak and brittle bones that break easily (osteoporosis), and loss of interest in sex. Pressure from a large tumor can cause vision problems, headache, and the pituitary gland to make less of other hormones.

Timing matters: females who haven't gone through menopause tend to notice symptoms earlier, when tumors are smaller — probably because of missed periods or periods that aren't regular. Females who have gone through menopause and males are more likely to notice symptoms later, when tumors are larger and more likely to cause headaches or vision problems.

When to See a Doctor

If you have symptoms that may be caused by a prolactinoma, see your health care professional.

If you have a prolactinoma and you want to become pregnant or already are pregnant, talk to your health care professional. How the prolactinoma is treated may need to change.

Causes

The cause of a prolactinoma often can't be found.

A prolactinoma causes the pituitary gland to make too much of the hormone prolactin. This lowers the amount of the sex hormones estrogen and testosterone in the body.

It is important to know that the pituitary gland can make a high amount of prolactin for reasons other than a prolactinoma. When a prolactin level comes back high, doctors consider several other possibilities:

Other cause of high prolactin	What it is
Medicines	Certain drugs can raise prolactin levels
Other pituitary tumors	Tumors other than prolactinoma can trigger prolactin overproduction
Kidney disease	Impaired kidneys can allow prolactin to build up
Thyroid problems	The thyroid gland not working correctly can raise prolactin
Pregnancy and breastfeeding	Normal, temporary increases in prolactin

Risk Factors

Risk factors for a prolactinoma include sex and genetics.

More prolactinomas happen in females than in males. The condition rarely happens in children.

Rarely, an inherited disorder such as multiple endocrine neoplasia type 1 (MEN1) — a condition that causes tumors in glands that make hormones — may raise the risk of a prolactinoma.

Risk factor	Detail
Sex	More common in females than males
Age	Rarely happens in children
Genetics	Rarely, the inherited disorder MEN1 raises the risk

Complications

Health concerns linked to a prolactinoma, called complications, may include infertility, bone loss, pregnancy-related concerns, vision problems, and low levels of other pituitary hormones.

Complication	How it develops
Infertility	Too much prolactin lowers estrogen and testosterone; it also can keep the body from releasing an egg during a menstrual cycle — a condition called anovulation — and can lower the amount of sperm the body makes
Osteoporosis	Less estrogen and testosterone causes a loss of bone strength, leading to weak and brittle bones that can break easily
Health concerns during pregnancy	Estrogen rises during pregnancy, which can cause a prolactinoma to grow; the growth may lead to headaches and vision changes in pregnant people who have a large prolactinoma
Vision problems	If not treated, the tumor may grow large enough to press on the optic nerve; the first sign of pressure on the optic nerve often is a loss of side vision, called peripheral vision
Low levels of other pituitary hormones	Larger prolactinomas can press on the healthy part of the pituitary gland, lowering thyroid hormone, growth hormone, and cortisol

Treatment Overview

Prolactinoma often can be treated with medicines to shrink the tumor and bring the prolactin level in the body down. Some people need surgery to remove the tumor.

Because a large prolactinoma can press on the optic nerve and lower other pituitary hormones, treatment aims to reduce both the tumor's size and the excess prolactin it produces. Related procedures used in the workup and treatment of pituitary tumors include MRI (imaging of the brain and pituitary), surgery through the nose and sinuses to remove the tumor (transsphenoidal surgery), and, in some cases, radiation therapy.

Preparing for Your Appointment

If you have symptoms that may be caused by a prolactinoma — missed or irregular periods, milky breast discharge, erectile dysfunction, unexplained infertility, or changes in your vision — start by seeing your health care professional. You may be referred to a doctor who specializes in hormone disorders, called an endocrinologist.

When you make the appointment, ask whether there are any pre-appointment restrictions, such as fasting before blood tests. Write down all your symptoms, including any that seem unrelated. Make a list of all medicines, vitamins, and supplements you take — because certain medicines can raise prolactin on their own, this list is especially important. If you are pregnant or trying to become pregnant, tell your health care professional, because treatment may need to change.

Questions worth bringing to the appointment include what may be causing your symptoms, what tests are needed, what treatment options are available, the benefits and risks of each option, and — if you have a prolactinoma — how it may affect pregnancy or how pregnancy may affect it.

Conclusion

Prolactinoma is a noncancerous tumor of the pituitary gland and the most common hormone-producing pituitary tumor. Although it is not life-threatening, it overproduces prolactin, lowering estrogen and testosterone and producing symptoms that differ by sex: missed or irregular periods and milky breast discharge in females, erectile dysfunction and gynecomastia in males, plus infertility, osteoporosis, and loss of interest in sex in anyone. If untreated, the tumor can press on the optic nerve — with loss of side vision often the first sign — and lower thyroid hormone, growth hormone, and cortisol. Risk factors are few: it is more common in females, rare in children, and rarely tied to the inherited MEN1 disorder. The good news is that medicines can often shrink the tumor and normalize prolactin, with surgery reserved for cases where medicines are not enough.

CTA: If you have unexplained changes in your menstrual cycle, milky breast discharge, erectile dysfunction, or difficulty getting pregnant, make an appointment with a health care professional — a simple blood test can check your prolactin level. If you already have a prolactinoma and want to become pregnant or already are pregnant, talk to your care team promptly, because treatment may need to change. Explore more Rinnit guides on hormone and brain health to understand how your endocrine system works and what to do when it does not.

Frequently Asked Questions

What is a prolactinoma?

Prolactinoma is a tumor of the pituitary gland that is not cancer. The tumor causes the pituitary gland to make too much of a hormone called prolactin, which lowers the body's levels of estrogen and testosterone.

Is a prolactinoma dangerous?

A prolactinoma isn't life-threatening. But it can cause health concerns, including vision problems, and it can make it hard to get pregnant by lowering estrogen and testosterone levels.

Is prolactinoma the most common pituitary tumor?

Yes — prolactinoma is the most common type of pituitary gland tumor that can make hormones.

What are the symptoms in females?

Females may have menstrual periods that are not regular or no menstrual periods, milky discharge from the breasts when not pregnant or breastfeeding, sore breasts, painful sex due to vaginal dryness, and acne and extra body and facial hair. Females before menopause tend to notice symptoms earlier, when tumors are smaller.

What are the symptoms in males?

Males may have erectile dysfunction, less body and facial hair, smaller muscles, and larger breasts, called gynecomastia. Males tend to notice symptoms later, when tumors are larger.

Can a prolactinoma cause infertility?

Yes. Too much prolactin lowers estrogen and testosterone, can keep the body from releasing an egg during a menstrual cycle (anovulation), and can lower the amount of sperm the body makes.

What happens if prolactinoma is not treated?

Untreated, it may grow large enough to press on the optic nerve — the first sign is often a loss of side (peripheral) vision — cause headaches, and press on the healthy part of the pituitary gland, lowering thyroid hormone, growth hormone, and cortisol. It can also cause osteoporosis and pregnancy-related complications, since rising estrogen during pregnancy can make the tumor grow.

How is a prolactinoma treated?

It often can be treated with medicines to shrink the tumor and bring the prolactin level in the body down. Some people need surgery to remove the tumor. If you want to become pregnant or are already pregnant, tell your health care professional, because treatment may need to change.