Endometriosis vs PCOS: how the two conditions differ

If the main problem is pain, especially severe period pain, pelvic pain, or pain when having sex or going to the toilet, endometriosis is the condition most associated with it. If the main problem is that periods are irregular or very far apart, with changes such as excess hair growth, acne or weight gain, PCOS is the condition most associated with it. Both can cause trouble getting pregnant, tiredness and low mood, which is where the confusion arises.

They are different conditions with different causes. Endometriosis is a disorder of where womb-lining-like tissue grows. PCOS is a disorder of hormone balance in which, the NHS says, hormones such as insulin and testosterone may not be working properly. The NHS notes that the cause of PCOS is unknown, and that it is also not known what causes endometriosis.

In endometriosis, the NHS says, cells similar to those in the lining of the womb grow in other parts of the body, often areas around the womb such as the ovaries, fallopian tubes and lining of the pelvis, and sometimes the bladder, bowel or even the chest. Symptoms happen when patches of endometriosis break down and bleed but cannot leave the body. It can affect anyone who has or had a womb.

PCOS, which the NHS now calls polyendocrine metabolic ovarian syndrome (PMOS), usually starts at puberty and continues until menopause. It can affect anyone who has ovaries. The NHS says it is linked with hormones such as insulin and testosterone not working properly, and that you may be more likely to have it if a close relative has it or you are from an Asian background.

The table uses the symptoms listed on the NHS pages and by Endometriosis UK. Having a symptom from one list does not rule out the other condition.

Both conditions can take time to diagnose. For endometriosis, the NHS says you might need several different tests because the symptoms can be similar to other conditions, including adenomyosis, fibroids, pelvic inflammatory disease and irritable bowel syndrome. A GP will ask about your symptoms and family history and may carry out a physical examination, including an internal vaginal exam, and blood tests. Further tests include an ultrasound scan, an MRI scan and a laparoscopy, a camera test through a small cut in the tummy that can confirm endometriosis and sometimes allows areas to be removed.

For PCOS, the NHS says a GP who thinks you may have it may arrange tests with a gynaecologist or endocrinologist. These include blood tests to check hormone levels and insulin resistance and an ultrasound scan of the ovaries, which is only done if you are over 18. Endometriosis UK reminds people that symptoms of endometriosis can also be symptoms of other health conditions, so it is important to seek medical advice to clarify the cause.

For endometriosis, the NHS says medicines are often the first treatment: painkillers such as paracetamol and ibuprofen, and hormones such as the combined contraceptive pill or other medicines that change hormone levels, which can help ease pain. You will not be given hormones if you are trying to get pregnant. If other treatments are not working, you have a lot of endometriosis or it is affecting your ability to have children, surgery may be offered to remove areas of endometriosis or cysts, or in some cases to remove the womb, ovaries or part of the bladder or bowel. More surgery may be needed if symptoms return.

For PCOS, the NHS lists the combined pill, progestogen-only pill or an intrauterine system for irregular periods, clomifene to improve fertility, spironolactone or eflornithine to reduce hair growth, weight loss medicines if you are overweight, metformin for tiredness and weight problems and skin creams or tablets for acne. If other treatments have not worked for fertility, a procedure called laparoscopic ovarian drilling may be suggested. Lifestyle measures such as a balanced diet, regular exercise and talking therapy are also listed.

Hormonal contraception is a shared tool, which is one reason people with either condition may be offered a similar first medicine for different reasons. It does not mean the conditions are the same.

The NHS says PCOS can sometimes increase the risk of type 2 diabetes, high blood pressure, cardiovascular disease, non-alcoholic fatty liver disease and womb cancer, and that regular check-ups can reduce that risk. Endometriosis is described by Endometriosis UK as not cancer, not an STI and not contagious. It states that up to 70% of those with endometriosis will be able to get pregnant naturally. Both conditions can affect mental health, and support is available from your GP and charities.

The NHS advice is the same for both: see a GP if you think you might have the condition or your symptoms are affecting your everyday life, work and relationships. For endometriosis it adds that you should return if treatment from a GP does not help or your symptoms get worse. Giving your GP as much detail as you can about the pattern of your periods, pain and any other symptoms makes it easier to decide which tests to arrange.