What is PCOS?

Polycystic ovary syndrome (PCOS) is a hormone imbalance that can cause irregular periods, unwanted hair growth, and acne. PCOS begins during a girl’s teen years and can be mild or severe.

Some of the most common signs of PCOS include:

  • Irregular periods that come every few months, not at all, or too frequently
  • Extra hair on your face or other parts of your body, called hirsutism (her-suit-is-em)
  • Acne
  • Weight gain and/or trouble losing weight
  • Patches of dark skin on the back of your neck and other areas, called acanthosis nigricans (a-can-tho-sis ni-gri-cans)

Check out our PCOS health guides.

Do you think you might have PCOS? Take our quiz to find out.


Our health guides are developed through a systematic, rigorous process to ensure accuracy, reliability, and trustworthiness. Written and reviewed by experienced healthcare clinicians from Boston Children's Hospital, a Harvard Medical School teaching hospital and consistently ranked as a top hospital by Newsweek and U.S. News & World Report, these guides combine clinical expertise, specialized knowledge, and evidence-based medicine. We also incorporate research and best practices from authoritative sources such as the CDC, NIH, PubMed, top medical journals, and UpToDate.com. Clinical specialists and subject matter experts review and edit each guide, reinforcing our commitment to high-quality, factual, scientifically accurate health information for young people.