- Endometriosis is tissue similar to the uterine lining growing outside the uterus, driving painful periods, chronic pelvic pain, and pain with sex; PCOS is a hormonal and metabolic condition marked by irregular periods, excess androgens, and often insulin resistance.
- The conditions overlap on irregular cycles, fatigue, and infertility, which is why they are frequently confused — but severe, cyclical pelvic pain points more to endometriosis, while acne, excess hair growth, and weight changes point more to PCOS.
- You can have both conditions at the same time, so a diagnosis of one does not rule out the other.
- PCOS is usually diagnosed from history, blood tests, and ultrasound (the Rotterdam criteria), while endometriosis is often confirmed with laparoscopy and can take years to identify.
- Treatment differs — pain control and cycle suppression for endometriosis, and lifestyle, cycle regulation, and metabolic care for PCOS — and your clinician tailors any medication and dosing to you.
- See a gynecologist for persistent pelvic pain, irregular periods, or trouble conceiving, and seek emergency care for sudden severe pain or very heavy bleeding.
Pelvic pain, irregular periods, and trouble getting pregnant — these symptoms could point to endometriosis, PCOS, or both. Endometriosis vs PCOS is one of the most common diagnostic dilemmas in women’s reproductive health, partly because the two conditions share several overlapping symptoms. According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development, roughly 6% to 10% of women of reproductive age have endometriosis, while the CDC estimates PCOS affects between 6% and 12% of the same population. Understanding what sets them apart — and where they overlap — is the first step toward getting the right diagnosis. This article is general education, not medical advice. For a broader look at gynecological and hormonal conditions, visit our medical conditions guide.
What Is Endometriosis?
Endometriosis occurs when tissue similar to the uterine lining (endometrium) grows outside the uterus — on the ovaries, fallopian tubes, bowel, or pelvic lining. Each menstrual cycle, this misplaced tissue responds to hormones much like the lining inside the uterus: it thickens, breaks down, and bleeds. But because that blood has no way to leave the body, it triggers inflammation, scar tissue (adhesions), and pain. The World Health Organization estimates that endometriosis affects roughly 190 million women and girls globally.
Severity varies widely, and symptom intensity does not reliably track the amount of visible disease. Some women have extensive lesions with minimal pain, while others have a few small implants that cause debilitating symptoms. According to Mayo Clinic, diagnosis has traditionally required laparoscopic surgery, though imaging is improving. You can learn more in our guide to symptoms of endometriosis.
What Is PCOS?
Polycystic ovary syndrome (PCOS) is a hormonal disorder characterized by excess androgen (male-type hormone) activity, irregular or absent ovulation, and — though not always — multiple small follicles on the ovaries. The CDC identifies PCOS as one of the most common causes of female infertility.
Unlike endometriosis, PCOS is fundamentally a hormonal and metabolic condition. Insulin resistance plays a central role in many cases, which is why women with PCOS face higher risks for type 2 diabetes, cardiovascular disease, and metabolic syndrome over time. Diagnosis commonly follows the Rotterdam criteria, which require at least two of three features: irregular periods, signs of elevated androgens (by exam or blood test), and polycystic-appearing ovaries on ultrasound, after other causes are excluded. Our detailed breakdown of symptoms of PCOS covers these signs in more depth.
Symptoms That Overlap
Part of the reason endometriosis vs PCOS confuses so many patients — and even some clinicians — is the symptom overlap. Both conditions can cause irregular menstrual cycles, though for different reasons. Endometriosis is more often associated with heavy or prolonged bleeding, while PCOS more often causes infrequent or absent periods because ovulation does not happen regularly.
Fertility challenges affect both groups. Endometriosis can distort pelvic anatomy, damage fallopian tubes, or create an inflammatory environment that makes conception harder. PCOS impairs fertility primarily by preventing regular ovulation. According to the American College of Obstetricians and Gynecologists, both rank among the leading causes of infertility. Fatigue, mood changes, and bloating appear in both conditions as well — chronic pelvic inflammation in endometriosis and hormonal imbalance in PCOS each take a real toll on energy and mental health.
Key Differences in Symptoms
Despite the overlap, several symptoms clearly distinguish one condition from the other. Recognizing these differences can help you have a more productive conversation with your doctor.
Pain Patterns
Endometriosis is defined by pain — often severe, cyclical pelvic pain that worsens around menstruation. Many women also experience pain during intercourse (dyspareunia), bowel movements, or urination. PCOS does not typically cause significant pelvic pain. When PCOS patients do feel discomfort, it is usually mild, and persistent or severe pelvic pain should prompt an evaluation for endometriosis or another cause.
Androgen-Related Symptoms
Signs of excess androgen are a hallmark of PCOS but not of endometriosis. Women with PCOS often develop acne (especially along the jawline), hirsutism (excess hair growth on the face, chest, or abdomen), and thinning hair on the scalp. These features are uncommon in endometriosis unless the two conditions coexist.
Weight and Metabolic Changes
Weight gain, particularly around the midsection, is closely associated with PCOS and its underlying insulin resistance, though not everyone with PCOS carries excess weight and the condition occurs in lean women too. Endometriosis has no direct link to weight gain, although some hormonal treatments can cause fluctuations. If metabolic symptoms dominate, PCOS is the more likely explanation.
Can You Have Both Endometriosis and PCOS?
Yes — and it happens more often than many patients realize. Research has reported that women with PCOS can also be diagnosed with endometriosis, and having both complicates the picture because symptoms can mask or mimic each other. If you have been diagnosed with one condition and your symptoms do not fully fit or your treatment is not working as expected, ask your provider about the possibility of a concurrent diagnosis. Some therapies that help PCOS (such as combined hormonal contraceptives) can also ease endometriosis symptoms, but targeted management of each condition tends to produce better outcomes.
Diagnosis: How Doctors Tell Them Apart
Diagnosing endometriosis vs PCOS calls for different approaches. For PCOS, clinicians typically take a menstrual and symptom history, order blood tests (which may include androgen levels and markers of blood sugar and insulin), and use a pelvic ultrasound that can reveal the characteristic “string of pearls” pattern of many small follicles. Because it relies on history, labs, and imaging, PCOS is frequently identified in a standard office visit once other conditions are ruled out.
Endometriosis is harder to confirm. While MRI and transvaginal ultrasound can detect deep lesions or endometriomas (“chocolate cysts”), a definitive diagnosis has traditionally required laparoscopy — a minimally invasive procedure in which a camera is inserted through a small abdominal incision. The NICHD notes that diagnosis is often delayed by years from the onset of symptoms, partly because imaging can miss smaller implants. Your doctor may also rule out other conditions that share symptoms, including uterine fibroids, pelvic inflammatory disease, thyroid dysfunction, and irritable bowel syndrome.
Treatment Approaches Compared
Treatment strategies share some common ground — hormonal contraceptives are used in both — but the overall goals differ. The options below are described in general terms; a clinician chooses and doses any medication based on your health, your goals (such as pain relief versus pregnancy), and other conditions. Do not start, stop, or adjust a prescription on your own.
Endometriosis Treatment
Pain management is a primary goal for many people with endometriosis. Over-the-counter anti-inflammatory pain relievers may help milder symptoms. Hormonal therapies — including combined birth control, progestin-based options, GnRH medications, and the hormonal IUD — aim to suppress the menstrual cycle and slow the growth of implants. Surgery (laparoscopic excision or ablation) may be considered for severe disease or when fertility is a priority. According to ACOG, treatment choices depend on symptom severity and whether you want to become pregnant.
PCOS Treatment
Because PCOS is a hormonal and metabolic condition, lifestyle measures — balanced nutrition, physical activity, and weight management when appropriate — form the foundation of care and can improve ovulation and insulin sensitivity. Medications that improve insulin sensitivity are sometimes used to address metabolic features. For cycle regulation, hormonal contraceptives are a common first-line option, and anti-androgen medications may help with acne and excess hair growth. When pregnancy is the goal, ovulation-induction medications are typically used under a clinician’s supervision. Your provider individualizes the plan and any dosing.
Frequently Asked Questions
Is pelvic pain always endometriosis and not PCOS?
Not necessarily, but chronic, severe pelvic pain that worsens during your period is far more characteristic of endometriosis. PCOS can occasionally cause mild pelvic discomfort, but persistent pain should prompt a discussion with your gynecologist about possible endometriosis or another cause.
Can a single ultrasound diagnose both conditions?
An ultrasound can support a PCOS diagnosis by showing polycystic-appearing ovaries, and it may detect endometriomas caused by endometriosis. However, most endometriosis implants are too small to appear on ultrasound, so a normal scan does not rule endometriosis out.
Does having endometriosis or PCOS mean I can’t get pregnant?
Neither condition automatically means infertility. Many women with endometriosis or PCOS conceive naturally or with medical assistance, and early diagnosis and appropriate treatment improve outcomes for both. The American Society for Reproductive Medicine generally suggests seeing a specialist after about 12 months of trying (or 6 months if you are 35 or older, or sooner with known risk factors).
Are there blood tests that tell endometriosis from PCOS?
Blood tests for androgens, blood sugar, and insulin can help support a PCOS diagnosis. There is no single reliable blood test that confirms endometriosis; CA-125 is sometimes elevated but is not a diagnostic test. Researchers continue to study biomarkers, but none had replaced clinical and surgical diagnosis of endometriosis as of 2026.
When to See a Doctor
If you experience persistent pelvic pain, irregular periods, difficulty conceiving, or any combination of the symptoms described above, schedule an appointment with a gynecologist or reproductive endocrinologist. Bring a symptom diary noting pain levels, cycle patterns, and any androgen-related changes like acne or hair growth — this information helps your provider distinguish between endometriosis vs PCOS more efficiently.
When to seek emergency care: Call 911 or go to the nearest emergency room if you have sudden, severe abdominal or pelvic pain, heavy vaginal bleeding that soaks through a pad every hour, or signs of ovarian torsion (sharp one-sided pain with nausea and vomiting).
The Bottom Line
Endometriosis and PCOS are distinct conditions with different root causes — tissue growth outside the uterus versus a hormonal and metabolic imbalance — but their overlapping symptoms make misdiagnosis common. Pain is the cardinal symptom of endometriosis, while androgen excess and metabolic disruption define PCOS, and some women have both. The most important step you can take is to track your symptoms carefully and advocate for thorough testing, because a correct diagnosis means targeted treatment and a clearer path to your goals.
This article is general education and is not medical advice or a substitute for care from a qualified clinician. Endometriosis and PCOS can look alike, and only a licensed healthcare provider can diagnose your condition and recommend or dose any treatment. Talk to a gynecologist about your symptoms, and call 911 or go to the nearest emergency room for sudden severe pelvic pain or very heavy bleeding.
Sources
- Mayo Clinic — Endometriosis and PCOS: symptoms, diagnosis, and treatment overviews
- American College of Obstetricians and Gynecologists (ACOG) — Endometriosis and PCOS FAQs
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD/NIH) — endometriosis condition information and diagnostic delay
- Centers for Disease Control and Prevention (CDC) — PCOS and infertility
- World Health Organization (WHO) — endometriosis fact sheet
- American Society for Reproductive Medicine (ASRM) — guidance on when to see a reproductive endocrinologist