If you live with endometriosis, you’ve probably had moments where your body throws something new at you that seems to have nothing to do with your pelvis at all: dizziness when you stand up too fast, a heart that races for no obvious reason, exhaustion that doesn’t match how much you’ve actually done.

A new study published in the journal Autonomic Neuroscience: Basic & Clinical gives solid, data-backed weight to what so many of you have been saying for a long time: endometriosis doesn’t stay in one place. This week’s Fact Friday breaks down what the researchers actually did, what they found, and what it might mean for you or someone you care about.

Before getting into the study, it’s worth resetting some of the basics, because endometriosis is still widely misunderstood, even within parts of the medical system.

Endometriosis is a full-body, systemic inflammatory disorder. It is not simply a “reproductive disease” or a condition confined to the pelvis, and it is not accurately described as a gynaecological condition: that framing, while common, undersells what is actually happening in the body. Endometriosis affects the reproductive system, but it is not a reproductive disease that happens to affect the rest of the body; it works the other way around. It is a whole-body inflammatory condition that happens to also affect the reproductive system, alongside the bowel, bladder, nervous system, and immune system, and, as this new research highlights, potentially the autonomic nervous system that controls things like heart rate and blood pressure.

It’s also important to clear up a persistent myth: endometriosis is not simply “oestrogen-dependent” in the way it’s often described. Endometriosis lesions don’t just respond passively to oestrogen made by the ovaries; they can actually produce their own oestrogen locally, fuelling inflammation and lesion growth independently. This is part of why endometriosis can persist or flare even when someone’s ovarian hormone levels are low, and why treatments that only target ovarian oestrogen don’t always bring full relief. Understanding endometriosis as a systemic inflammatory condition, rather than a narrowly hormonal or “gynaecological” one, is exactly why studies like this new POTS research matter so much.

POTS stands for Postural Orthostatic Tachycardia Syndrome. In plain terms, it’s a condition affecting the autonomic nervous system, the part of your nervous system that runs things automatically in the background, including your heart rate, blood pressure, digestion, and temperature regulation.

People with POTS experience a sharp increase in heart rate when they move from lying or sitting to standing, along with symptoms like dizziness, lightheadedness, fainting or near-fainting, brain fog, fatigue, and heart palpitations. Doctors typically confirm POTS using a “tilt table test,” where a person is strapped to a table that slowly tilts them upright while their heart rate and blood pressure are monitored.

Clinicians working in chronic pain and autonomic (nervous system) clinics have noticed, anecdotally, that an unusually high number of their POTS patients also seem to have endometriosis. This new study set out to actually measure that overlap properly, using real patient data rather than impressions from the clinic floor.

The research team, led by Adeline Y. Chin and colleagues at the Cleveland Clinic in the United States, carried out a retrospective case-control analysis, meaning they looked back through existing medical records rather than running a new experiment from scratch.

They reviewed the records of patients who had presented to their autonomic specialty centre for tilt table testing between 2018 and 2024. POTS was defined using the standard clinical criteria: symptoms of orthostatic intolerance (feeling unwell when upright) combined with a heart rate increase of at least 30 beats per minute within the first ten minutes of the tilt table test.

For each patient, the researchers also checked whether there was a documented diagnosis of endometriosis, confirmed either through surgical pathology (tissue removed and examined under a microscope, the gold-standard way of diagnosing endometriosis) or through clinical documentation by a gynaecologic specialist.

Crucially, the study didn’t just look at people who tested positive for POTS. It also included a comparison group of patients who were tested for POTS but had a negative result (a “tilt-negative” cohort), which allows the researchers to see whether endometriosis really clusters specifically around POTS, rather than just around people who attend autonomic clinics in general.

The numbers here are striking. Among 1,322 female patients with a confirmed POTS diagnosis:

• 229 patients (17.3%) also had a diagnosis of endometriosis.
• This is significantly higher than the roughly 10% prevalence of endometriosis estimated in the general female population.
• It’s also significantly higher than the 10.2% prevalence found in the tilt-negative comparison group, people tested at the same clinic who did not meet criteria for POTS.
• Both of these differences were statistically significant (p < 0.001), meaning they’re very unlikely to be down to chance.

Just as interesting is the order in which people were diagnosed. Among patients who ended up with both conditions:

• 68% (156 patients) were diagnosed with endometriosis first, before their POTS diagnosis.
• 32% (73 patients) were diagnosed with POTS first, before endometriosis was identified.

In other words, there’s no single, simple direction to this relationship. It seems to run both ways, with each condition sometimes acting as an early clue that the other might also be present.

So what do you actually do with this information if you’re living with endometriosis, caring for someone who is, or wondering whether your own unexplained symptoms might be connected?

1. It validates whole-body symptoms that are often dismissed. If you’ve mentioned dizziness, racing heart, fainting spells, or extreme fatigue on standing to a clinician and felt brushed off, this research adds weight to the idea that these symptoms deserve proper investigation, not automatic dismissal as anxiety or unrelated issues.
2. It’s a two-way street worth knowing about. If you already have an endometriosis diagnosis and you’re experiencing symptoms of orthostatic intolerance, feeling faint or your heart pounding when you stand, especially if it’s a regular pattern rather than a one-off, it may be worth raising POTS as a possibility with your doctor, potentially with a referral for tilt table testing.
3. The reverse applies too. If you have a POTS diagnosis and also experience pelvic pain, very painful periods (dysmenorrhea), or other symptoms consistent with endometriosis that haven’t been formally investigated, this research suggests it may be worth pursuing that conversation rather than assuming the two are unconnected.
4. It reinforces that endometriosis is systemic. This is really the heart of why this study matters for Fact Friday. An overlap this strong with a condition of the autonomic nervous system, not the reproductive organs, is further evidence that endometriosis is a full-body inflammatory condition, not a disease that stays neatly contained to the pelvis. The exact biological mechanism linking endometriosis and POTS isn’t nailed down yet (the researchers don’t claim to have solved that puzzle), but the strength and consistency of the association is hard to ignore.
5. It may help explain “invisible” exhaustion. Many people with endometriosis describe a bone-deep fatigue that doesn’t match their activity levels. Undiagnosed POTS, which causes real physiological fatigue through blood pressure and heart rate dysregulation, could be a contributing factor worth ruling in or out for some people.

As with any single study, it’s important to understand what this research can and can’t tell us:

• It’s retrospective. The researchers looked back at existing records rather than tracking people forward over time, which means the findings describe an association, not a proven cause-and-effect relationship.
• It’s a specialist clinic sample. The patients studied had already been referred to a specialist autonomic centre for tilt table testing, which may not reflect the general population of people with POTS or endometriosis. People referred to specialist centres often have more complex or severe symptom profiles.
• Diagnosis methods varied. Endometriosis diagnosis in the study came from either surgical pathology or clinical documentation by a gynaecologic specialist; these aren’t identical standards, and clinical diagnosis without surgery can sometimes be less certain than a pathology-confirmed one.
• It doesn’t explain the “why” yet. This study establishes that the two conditions co-occur far more than chance would predict, and gives us a sense of diagnostic order, but it does not identify the underlying biological mechanism connecting them. Future research will need to dig into that.
• Single-centre data. The findings come from one autonomic specialty centre in the United States; results could vary in other populations, healthcare systems, or countries.

Studies that connect endometriosis to conditions well outside the reproductive system are exactly the kind of research that helps reshape outdated ideas about what endometriosis is. For a long time, the narrative has been narrow and incomplete, treating endometriosis as a straightforward “period problem” rather than recognising it as the complex, whole-body inflammatory condition it is. Research like this gives both patients and clinicians a stronger evidence base for taking whole-body symptoms seriously and investigating them properly, rather than treating the pelvis in isolation from the rest of the body.

• A new retrospective study found that 17.3% of patients with POTS also had endometriosis, nearly double the estimated prevalence in the general female population and significantly higher than in a comparison group who tested negative for POTS.
• Among people with both conditions, endometriosis was diagnosed first in most cases (68%), with POTS diagnosed first in the remainder (32%), suggesting either condition can be an early signal to look for the other.
• The study adds further evidence that endometriosis is a systemic, full-body inflammatory condition, consistent with its ability to affect the autonomic nervous system, not just the reproductive system.
• If you have dizziness, fainting, or a racing heart on standing (with or without an endometriosis diagnosis), or pelvic pain and heavy or painful periods (with or without a POTS diagnosis), it may be worth discussing both possibilities with your healthcare provider.
• This is one retrospective study from a single specialist centre. It points to an important association, not a confirmed cause, and more research is needed to understand the mechanism behind it.

This Fact Friday breakdown is based on: Chin AY, Rilinger RG, Levine M, Nowacki AS, Brant AR, Cameron C, Gubbels A, Wilson R. “The endometriosis-POTS connection: A retrospective analysis.” Autonomic Neuroscience: Basic & Clinical, 2026;267:103469.

https://doi.org/10.1016/j.autneu.2026.103469

This article summarises a single piece of research and is provided for general information and education only. It is not medical advice. Everyone’s body and situation is different, so if anything here resonates with your own experience, please raise it with your own GP, gynaecologist, cardiologist, or autonomic specialist, who can properly assess your individual symptoms and history.