What are the key differences between PCOS and endometriosis?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Polycystic ovary syndrome (PCOS) and endometriosis are two distinct conditions that affect women's reproductive health, though they share overlapping symptoms like pelvic pain and irregular periods. PCOS is a hormonal disorder marked by elevated androgen levels, irregular ovulation, and small ovarian cysts. Endometriosis, by contrast, occurs when tissue similar to the uterine lining grows outside the uterus, causing inflammation, scarring, and often severe pain. Because their symptoms can mimic each other, accurate diagnosis is essential for effective treatment.

If you're experiencing symptoms and unsure whether PCOS, endometriosis, or another condition may be the cause, taking a free, instant, online symptom check can help clarify your next steps. It's a fast, private way to understand what your body may be signaling and get personalized guidance on when to see a doctor—so you don't have to navigate the uncertainty alone.

Reviewed for medical accuracy: 07/15/2026

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Explanation

Polycystic Ovary Syndrome (PCOS) and endometriosis are both conditions that affect women, but they are quite different in how they present and affect the body.

PCOS:

PCOS is a hormonal disorder that often leads to irregular periods, excess hair growth, and sometimes cysts on the ovaries.
It is associated with higher levels of male hormones, which can cause symptoms like acne and weight gain.

Endometriosis:

Endometriosis involves the growth of tissue similar to the lining inside the uterus, but it grows outside the uterus.
It can cause painful periods, pain during intercourse, and sometimes fertility issues.

Both conditions can affect fertility, but they do so in different ways. PCOS is more about hormonal imbalances, while endometriosis is about tissue growing where it shouldn't. If you're experiencing any of these symptoms and want personalized guidance, you can use our free AI symptom checker to better understand what might be happening with your body and determine the right next steps for treatment.

(References)

Dinsdale NL, & Crespi BJ. (2021). Endometriosis and polycystic ovary syndrome are .... Evolutionary applications, 34295358.
Kirkegaard S, Uldall Torp NM, Andersen S, & Andersen SL. (2024). Endometriosis, polycystic ovary syndrome, and the thyroid. Endocrine connections, 38078917.
Petraglia F, Musacchio C, Luisi S, & De Leo V. (2008). Hormone-dependent gynaecological disorders. Best practice & research. Clinical obstetrics & gynaecology, 17804298.

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