What is the difference?

Endometriosis vs PCOS

Endometriosis and PCOS are both common long-term conditions that can affect periods and fertility, and both are often diagnosed late. They are quite different, though: endometriosis is mainly about tissue growing in the wrong place and pain, PCOS mainly about hormones and irregular cycles.

General information, not medical advice. For advice about your own situation, talk to a clinician, pharmacist or sexual health clinic.

Body & health

Endometriosis

Endometriosis is a long-term condition in which tissue similar to the lining of the uterus grows elsewhere in the body, most often in the pelvis, causing inflammation, pain and sometimes fertility problems.

Full entry
Body & health

PCOS

Polycystic ovary syndrome (PCOS) is a common hormonal condition that can cause irregular or absent periods, higher levels of androgens, and many small follicles on the ovaries.

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Side by side

EndometriosisPCOS
What it isEndometriosisTissue similar to the lining of the uterus grows elsewhere, most often in the pelvis.PCOSA hormonal condition involving irregular ovulation, higher androgen levels and insulin resistance.
Typical periodsEndometriosisOften very painful, sometimes heavy.PCOSOften irregular, infrequent or absent.
Other common signsEndometriosisChronic pelvic pain, pain during sex or when using the toilet, fatigue.PCOSExcess facial or body hair, acne, scalp hair thinning, weight changes.
How it is diagnosedEndometriosisSymptom history and imaging; keyhole surgery (laparoscopy) may be needed to confirm it.PCOSSymptom history, blood tests for hormones and sometimes an ultrasound scan.
Long-term healthEndometriosisOngoing pain that can affect daily life and mental health.PCOSHigher risk of type 2 diabetes, high blood pressure and heart disease.
Other namesEndometriosisSometimes shortened to endo.PCOSSome services, including the NHS, now use the name polyendocrine metabolic ovarian syndrome (PMOS).

In short

Endometriosis usually shows up as pain; PCOS usually shows up as irregular cycles and hormone-related signs. Period pain or irregularity that affects daily life deserves a doctor's attention.

What they have in common

Each affects roughly one in ten women and girls of reproductive age, according to the WHO; both can make getting pregnant harder; neither has a cure; and both can be managed with treatment, including hormonal medication. Some people have both.

Sources

  1. WHOEndometriosis fact sheet
  2. WHOPolycystic ovary syndrome fact sheet
  3. NHSPolyendocrine metabolic ovarian syndrome (PMOS)

More comparisons

Last reviewed 16 October 2026. Spotted a mistake?