If you have ever searched painful periods or irregular cycles, two terms come up repeatedly: PCOS and endometriosis. They are both common, both underdiagnosed, and both capable of affecting fertility and quality of life. Yet they are very different conditions, which is why understanding the distinction matters. It helps you track the right symptoms, ask better questions, and push for the right tests and treatment.
What PCOS is
Polycystic ovary syndrome is a hormonal condition that affects how the ovaries function. It is often linked to higher levels of androgens, hormones that everyone produces but that can be elevated in PCOS. Ovulation may not happen regularly, eggs may not mature as they should, and an ultrasound can show enlarged ovaries with many small follicles.
PCOS often shows up through cycle changes and skin or hair clues. Periods may be irregular or absent. You might notice persistent acne, oily skin, thinning hair on the scalp, or increased hair growth on the face, chest or abdomen. Many people with PCOS also have insulin resistance, which can make weight management harder and raise the long-term risk of type 2 diabetes and metabolic complications.
Pain is not usually the headline symptom. Some people feel discomfort from enlarged ovaries, but severe cyclical pelvic pain is less typical.
What endometriosis is
Endometriosis is a condition where tissue similar to the lining of the uterus grows outside the womb. This tissue can attach to the ovaries, fallopian tubes, bladder, bowel or other pelvic structures. It responds to hormonal shifts across the menstrual cycle, which can trigger inflammation, scarring and adhesions.
The signature feature is pain. Many people experience severe period pain, chronic pelvic pain, pain during or after sex, and pain when opening the bowels or passing urine during their period. Heavy or prolonged bleeding can occur, and fertility challenges are common. Symptoms vary widely. Some have mild signs, while others have debilitating pain that interrupts daily life.
The difference in plain language
PCOS is primarily hormonal and metabolic. Endometriosis is primarily inflammatory and structural.
If your main pattern is irregular cycles paired with acne, hair growth changes or weight and insulin issues, PCOS becomes more likely. If your main pattern is severe cyclical pain, deep pelvic pain and pain linked to sex or bowel movements, endometriosis rises higher on the list.
Both can affect fertility, but they do so for different reasons. PCOS tends to interfere with regular ovulation. Endometriosis can disrupt pelvic structures and create inflammation that affects implantation and egg quality.
How diagnosis usually works
PCOS is typically diagnosed through a combination of symptom history, blood tests and ultrasound. Many clinicians use the Rotterdam criteria, which require any two of the following: irregular or absent ovulation, evidence of raised androgens, or polycystic-appearing ovaries on ultrasound.
Endometriosis can be harder to confirm. Ultrasound and MRI can detect some forms, particularly ovarian endometriomas, but a definitive diagnosis often relies on laparoscopy, a minor surgical procedure that allows visual inspection and biopsy. Because symptoms can overlap with other conditions, keeping a clear symptom and cycle record helps clinicians make faster, better decisions.
Can you have both
Yes, though it is not common. One does not cause the other, and having one does not protect you from developing the other. If your symptoms feel mixed, such as irregular cycles combined with severe pelvic pain, it is worth pushing for a thorough assessment rather than trying to fit everything into one label.
Why the right diagnosis changes treatment
PCOS management often focuses on regulating cycles, improving insulin sensitivity, reducing androgen-related symptoms, and supporting fertility when needed. Lifestyle changes can play a meaningful role alongside medical options, particularly around blood sugar regulation, strength training, sleep and stress.
Endometriosis treatment often combines hormonal therapies to suppress tissue activity, pain management strategies, and sometimes surgery for severe disease or persistent symptoms. Fertility support may be needed depending on severity and goals.
Both conditions benefit from a long-term plan, but the plan is not the same.
When to seek medical advice
Speak to a healthcare professional if you have periods that are consistently irregular, pain that disrupts work or daily life, signs of raised androgens such as excess hair growth or persistent acne, or difficulty conceiving. Early assessment can improve symptom control and reduce long-term complications.
PCOS and endometriosis can look similar on the surface because both affect periods and fertility, but they have different causes and different treatment paths. PCOS centres on hormone imbalance and ovulation disruption. Endometriosis centres on tissue growth outside the womb and inflammation that often drives pain. Tracking your cycle and symptoms, then taking that record to a GP or gynaecologist, is one of the most powerful first steps towards clarity and proper care.
ALSO SEE:
Hormone-friendly habits every woman in her 20s–40s should know
Featured Image: Pexels
