Endometriosis: everything you need to know

Endometriosis is one of the most common gynaecological conditions, affecting around one in 10 women and people assigned female at birth of reproductive age in the UK.^1,2 Although it's common, it can still take years for people to receive an accurate diagnosis, with endometriosis symptoms often being mistaken for other conditions.

Endometriosis is a condition where tissue similar to the lining of the womb (endometrium) grows outside the uterus.³ These growths are most commonly found on the ovaries, fallopian tubes, the lining of the pelvis and surrounding organs – although they can occasionally occur elsewhere in the body.³ Like the lining of the womb, this tissue responds to hormonal changes during the menstrual cycle. However, due to this tissue sitting outside the uterus, it can lead to inflammation, irritation and the formation of scar tissue (adhesions) and cysts in some people.⁴ Endometriosis affects everyone differently. Some people experience severe endometriosis symptoms despite having relatively small areas of endometriosis, while others have more of an extensive condition but with few or no symptoms.⁵ Meaning, symptoms don't always reflect how advanced the condition is.

The exact answer to what causes endometriosis isn't fully understood. Researchers believe it's likely to develop due to a combination of genetic, hormonal, immune and environmental factors rather than a single cause.^3,6 Several theories have been proposed to explain why endometriosis develops, including menstrual tissue travelling backwards through the fallopian tubes (known as retrograde menstruation), changes in cells outside the womb and differences in how the immune system responds.^3,7 However, none of these theories fully explains every case. Importantly, endometriosis isn’t caused by anything you've done – and there's currently no known way to prevent it. Some factors linked with a higher likelihood of developing endometriosis include:

Endometriosis symptoms vary from person to person.^3,5 Some people notice symptoms from their teenage years, while others don't develop them until later in life. Although fertility can be affected by endometriosis, many people with the condition can still conceive naturally.¹⁰ Others may benefit from fertility treatment if needed, so a diagnosis doesn't automatically mean you'll experience infertility. Common symptoms of endometriosis include:³

Endometriosis pain isn't just ‘bad period pain’. It can happen at different times throughout the month and affect different parts of the body, depending on where the endometriosis is located. Some people describe the pain as sharp, stabbing, throbbing, cramping or aching.¹¹ Others experience constant pelvic pain that doesn’t just happen during their period. The amount of pain someone experiences doesn't always match the stage of their endometriosis. Pain may be felt in the:

Healthcare professionals may classify endometriosis into four stages based on the location, depth and extent of endometriosis tissue and scar tissue. It's important to remember that these stages don't predict how painful symptoms will be or whether you’ll have fertility difficulties. 

Getting an endometriosis diagnosis can sometimes take time because the symptoms overlap with other conditions, including irritable bowel syndrome (IBS), pelvic inflammatory disease and common menstrual pain.⁵ Your GP will usually begin by discussing your symptoms and medical history before carrying out an examination if appropriate. Depending on your symptoms, you may then be referred to a gynaecologist.³ Further investigations may include:

Many people notice that their symptoms come and go in flare-ups. Keeping a symptom diary can help identify personal patterns and support conversations with your healthcare team. While triggers vary between individuals, common factors include:

“Some people notice that certain triggers seem to worsen symptoms, particularly during flare-ups, but these are highly individual," says Molly. "Keeping a simple diet, lifestyle and symptom diary can help you identify patterns, although it's important not to unnecessarily restrict large food groups without professional advice."

There isn't currently a cure for endometriosis, but there are several effective treatment options that can help manage symptoms. Treatment of endometriosis is tailored to each person and depends on factors including symptoms, age, whether pregnancy is planned and the severity of the condition. Treatment options may include:

Living with endometriosis can be physically and emotionally exhausting. Flare-ups may affect your work, social life, relationships and confidence, and many people describe feeling frustrated by the unpredictability of their symptoms. If that's how you're feeling, you're not alone.

Stay active where possible

Eat a balanced diet

Prioritise sleep 

Manage stress

Build a support network

Most importantly, be kind to yourself

Living with endometriosis can feel overwhelming, particularly if you've spent years searching for answers. It can affect your body, your mental wellbeing, your relationships and your day-to-day life in ways that aren't always visible to others. While there isn't currently a cure, earlier diagnosis and the right endometriosis treatment can help many people manage their endometriosis symptoms and improve their quality of life. If something doesn't feel right, trust what your body is telling you and don't be afraid to seek medical advice.

Disclaimer – This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.