Types

Polycystic Ovary Syndrome

Choose a preferred language

Polycystic ovary syndrome (PCOS) causes harmless, small cysts in the ovaries and other symptoms. PCOS is caused by certain hormones being out of balance. The word syndrome means a group of symptoms. Women with PCOS may have no periods, irregular periods, or very long or heavy periods.


Your ovaries

Women store their eggs in their ovaries. Each egg is in a capsule called a follicle. Normally during the reproductive years, one follicle grows to make a mature egg each month. This egg is released during ovulation and the follicle dissolves.

Front view of female reproductive tract with insets showing normal ovary and polycystic ovary.


Hormones out of balance

With PCOS, the hormones that control ovulation are out of balance. These include estrogen, progesterone, and androgen. As a result, ovulation may not occur. Instead, the follicle stays enlarged. This is a fluid-filled sac called a cyst. Over time, the ovaries fill with many small cysts. This is why they are called poly or many cystic ovaries. In some women, the ovaries also make too much androgen.


Symptoms of PCOS

Women with PCOS may also have one or more of these symptoms:

  • Acne

  • Hair growth on the face and other parts of the body

  • Patches of thick, velvety, dark skin (acanthosis nigricans), often on the neck or groin area

  • Trouble getting pregnant (fertility problems)

  • Weight gain, often around the waist 

Women with PCOS are also at greater risk of having cancer of the uterine lining, diabetes, and heart disease.

Featured in

Online Medical Reviewer: Donna Freeborn PhD CNM FNP

Online Medical Reviewer: Heather M Trevino BSN RNC

Online Medical Reviewer: Howard Goodman MD

Date Last Reviewed: 05/01/2025

© 2000-2025 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
doctor icon

Find the right provider to meet your needs

From primary care to specialty services and more.

Find a Doctor
appointment clock icon

Call for an Appointment

Offering personalized care at more than 20 clinics across three cities and two states.

Call Now
Related Articles
Read article
Metabolic Conditions
Thyroid Disorders in Those Born Female

Detailed information on thyroid disorders and how they affect women, including puberty, pregnancy, and menopause.

Read article
Metabolic Conditions
Hyperthyroidism

Hyperthyroidism means your thyroid gland is too active. This tiny gland is found in your neck. An overactive thyroid gland makes too much thyroid hormone. This makes your metabolism work at a faster rate.

Read article
OB/GYN
Hysterosalpingogram (HSG)

HSG is an X-ray test used to view your uterus and fallopian tubes. It's most often used to help diagnose why you are not able to get pregnant.

Read article
OB/GYN
Primary Ovarian Insufficiency

Primary ovarian insufficiency, or POI, is when the ovaries stop working normally before the age of 40. With POI, the ovary does not release an egg each month as it should. POI has been called premature ovarian failure and premature menopause.