What Is PCOS?
Polycystic Ovary Syndrome is the most common hormonal disorder in women — yet most women go years without a diagnosis. Here's everything you need to understand it.
Last reviewed: June 25, 2025
HerPCOS Editorial Team
Evidence-based health content for women with PCOS
Last reviewed
June 25, 2025
This content is for general informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and treatment.
PCOS in Plain Language
PCOS (Polycystic Ovary Syndrome) is a hormonal condition in which the ovaries produce too many androgens — the hormones often thought of as "male hormones," like testosterone. Every woman produces some androgens naturally, but in PCOS, levels are higher than normal, which disrupts the hormonal signals needed for regular ovulation.
PCOS affects approximately 1 in 10 women of reproductive age worldwide — around 200 million women globally. It is the most common endocrine disorder in women and the leading cause of ovulatory infertility. Despite being so common, up to 70% of women with PCOS go undiagnosed, often for years.
The name "polycystic" refers to the appearance of the ovaries on ultrasound — many small follicles (immature eggs) that didn't develop fully. Importantly, these aren't true cysts and don't always cause pain. You can also have PCOS without them showing up on an ultrasound at all.
1 in 10
Women affected
70%
Go undiagnosed
#1
Cause of ovulatory infertility
What Causes PCOS?
PCOS doesn't have a single cause — it results from a combination of genetic predisposition and metabolic dysfunction. Two mechanisms are central to most cases:
Insulin Resistance
Up to 70% of women with PCOS have insulin resistance — their cells don't respond well to insulin, so the body produces more of it to compensate. High insulin levels directly signal the ovaries to produce excess testosterone and other androgens, triggering the hormonal cascade behind most PCOS symptoms. This is why insulin resistance is considered the primary driver of PCOS in most women.
Abnormal Brain–Ovary Signalling
The hypothalamus (brain) sends signals (GnRH pulses) to the pituitary gland, which releases LH and FSH to control the menstrual cycle. In PCOS, these pulses are faster than normal, causing LH levels to stay chronically elevated. High LH stimulates the ovaries to overproduce androgens and prevents the LH surge needed for ovulation — which is why periods become irregular or absent.
Genetics
PCOS runs in families. If your mother or sister has PCOS, your risk is significantly higher. Multiple genes involved in insulin signalling, androgen production, and gonadotropin regulation have been linked to PCOS. Environmental factors — diet, stress, exposure to endocrine disruptors — can trigger or worsen PCOS in those who are genetically predisposed.
The 4 Types of PCOS
Not all PCOS is the same. Understanding which type you have helps explain your specific symptoms and guides which treatments are most likely to work.
Insulin-Resistant PCOS
Most common~70% of cases
The most common type. High insulin levels stimulate the ovaries to overproduce androgens. Responds well to dietary changes, Metformin, and inositol. Often associated with weight gain but can occur in lean women too.
Adrenal PCOS
~10% of cases
Driven by elevated DHEAS (an adrenal androgen) rather than ovarian androgens. Often triggered by stress. Testosterone and insulin may be normal. Requires a different management focus — stress reduction and adrenal support.
Inflammatory PCOS
~10–20% of cases
Chronic low-grade inflammation stimulates the adrenal glands and ovaries to produce excess androgens. Often associated with fatigue, headaches, skin issues, and bowel problems. An anti-inflammatory diet is key.
Post-Pill PCOS
Temporary condition
Some women develop PCOS-like symptoms after stopping hormonal contraception as the body recalibrates. Androgens can temporarily surge and periods may become irregular. Usually resolves within 3–6 months without treatment.
Note: These categories are based on common clinical patterns and are not official WHO classifications. Many women have features of more than one type.
Common PCOS Symptoms
PCOS presents differently in every woman — you may have all, some, or only a few of these symptoms. Their severity also varies widely. See our full PCOS symptoms guide for detailed explanations of each.
Irregular or absent periods
Cycles longer than 35 days, or fewer than 8 per year
Excess hair growth (hirsutism)
On face, chest, abdomen, or back — driven by androgens
Acne
Hormonal acne, typically along the jawline and chin
Scalp hair thinning
Androgenic alopecia — thinning at the part or crown
Weight gain or difficulty losing weight
Especially around the abdomen — linked to insulin resistance
Fatigue
Often related to blood sugar instability and poor sleep
Mood changes
Anxiety and depression are 2–3× more common in PCOS
Difficulty getting pregnant
Irregular ovulation is the main cause of PCOS-related infertility
How Is PCOS Diagnosed?
There is no single test for PCOS. Diagnosis is based on the Rotterdam Criteria — the internationally accepted standard since 2003. You need to meet at least 2 of the following 3 criteria, after ruling out other conditions that could explain your symptoms:
Irregular or Absent Ovulation
Cycles that are consistently longer than 35 days, shorter than 21 days, or absent. This is the hallmark feature and the most common.
Elevated Androgens
Either clinically (symptoms like acne, hirsutism, or scalp hair loss) or biochemically (elevated testosterone or DHEAS on blood tests).
Polycystic Ovaries on Ultrasound
12 or more small follicles (2–9mm) in at least one ovary, or an ovarian volume greater than 10 mL. Despite the name, true 'cysts' are rarely present.
Before diagnosing PCOS, your doctor should rule out other conditions with similar symptoms: thyroid disease, hyperprolactinaemia, congenital adrenal hyperplasia, and Cushing's syndrome. Our lab results guide covers all the tests involved.
How Is PCOS Treated?
PCOS management is personalised — your treatment depends on your symptoms, whether you want to conceive, and your underlying metabolic picture. There is no one-size-fits-all approach, but these are the main tools available:
Diet & Lifestyle
A low-GI, anti-inflammatory diet is the foundation of PCOS management. Even modest improvements in diet and exercise can restore ovulation and reduce symptoms.
Read the diet guide →Metformin
The most commonly prescribed medication for PCOS — improves insulin sensitivity, lowers androgens, and may restore regular periods.
Read the Metformin guide →Inositol
A natural supplement with strong research support for improving insulin sensitivity, restoring ovulation, and reducing androgen levels without a prescription.
Read the inositol guide →Hormonal Contraceptives
Combined oral contraceptives regulate periods and reduce androgen-driven symptoms like acne and hirsutism. They don't treat the underlying cause but manage symptoms effectively.
See all symptom treatments →Fertility Treatments
If pregnancy is the goal, letrozole (ovulation induction) is first-line. IVF is available if simpler treatments don't work. PCOS responds well to fertility treatment.
Read the fertility guide →Monitoring with Labs
Regular blood tests track hormone levels, insulin, and metabolic health. Understanding your results helps you measure progress and guide treatment decisions.
Read the lab results guide →Long-Term Health With PCOS
PCOS is a lifelong condition. Beyond reproductive symptoms, women with PCOS carry an elevated risk of several long-term health conditions — especially if insulin resistance is not managed:
Type 2 Diabetes
Women with PCOS have 5–10× higher lifetime risk. Up to 10% have type 2 diabetes by age 40.
Cardiovascular Disease
Higher rates of high blood pressure, high triglycerides, and low HDL cholesterol increase heart disease risk.
Endometrial Cancer
Infrequent or absent periods mean the uterine lining builds up without regular shedding, raising cancer risk if untreated.
Sleep Apnoea
5–10× more common in women with PCOS, even in those who are not overweight. Often underdiagnosed.
Mental Health
Anxiety and depression are 2–3× more prevalent in PCOS. The chronic nature of the condition and body image concerns contribute.
The good news: managing PCOS proactively — through diet, lifestyle, and appropriate treatment — significantly reduces all of these long-term risks. Early diagnosis and management matter.
Frequently Asked Questions
What does PCOS stand for?+
Is PCOS common?+
What causes PCOS?+
Can you have PCOS without cysts on your ovaries?+
Can thin or lean women get PCOS?+
Is PCOS the same as having polycystic ovaries?+
Does PCOS go away after menopause?+
Can PCOS be cured?+
Medical References
- [1]Azziz R, et al. (2016). Polycystic ovary syndrome. Nat Rev Dis Primers. 2:16057.
- [2]March WA, et al. (2010). The prevalence of polycystic ovary syndrome in a community sample assessed under contrasting diagnostic criteria. Hum Reprod. 25(2):544–551.
- [3]Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. (2004). Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome. Fertil Steril. 81(1):19–25.
- [4]Teede HJ, et al. (2018). International evidence-based guideline for the assessment and management of polycystic ovary syndrome. Hum Reprod. 33(9):1602–1618.
- [5]Dunaif A. (1997). Insulin resistance and the polycystic ovary syndrome: mechanism and implications for pathogenesis. Endocr Rev. 18(6):774–800.
This content is for general informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and treatment.
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