Can Endometriosis Cause Joint Pain?

Endometriosis can contribute to joint pain, though the relationship is indirect and runs through several overlapping pathways rather than a single straightforward mechanism. Women with a history of endometriosis report more musculoskeletal pain sites and lower pain tolerance than women without the condition, even at areas far from the pelvis. The reasons involve systemic inflammation, changes in how the nervous system processes pain, a higher risk of autoimmune conditions that attack joints directly, and in rare cases, endometriotic tissue physically growing in or near a joint. Understanding which pathway is driving the pain matters, because each calls for a different approach.

How Endometriosis Spreads Pain Beyond the Pelvis

Endometriosis is defined by tissue similar to the uterine lining growing outside the uterus, and the most recognized symptoms are pelvic pain, painful periods, and pain during sex. But a growing body of evidence shows that the disease’s effects reach well beyond the pelvis. A large population-based study following women to age 46 found that those with endometriosis reported significantly more pain sites across the body and rated their pain as more troublesome and intense than women without the condition. Roughly a quarter of the endometriosis group reported pain in five to eight different body areas, compared with about one in five controls.¹ That kind of widespread pain pattern often includes joints, though endometriosis itself is not eating away at cartilage the way arthritis does. Instead, several biological mechanisms converge to make the whole body more pain-prone.

Chronic Inflammation That Does Not Stay Local

Endometriotic lesions are not quiet tissue. They provoke an ongoing immune response that raises inflammatory signals throughout the bloodstream. Research has shown that women with endometriosis have significantly higher blood levels of key inflammatory molecules, including IL-1β, IL-6, and TNF-α, compared with women free of the disease.² These are the same cytokines implicated in joint inflammation, cartilage breakdown, and the pain of conditions like rheumatoid arthritis. When they circulate at elevated levels for months or years, they can sensitize tissues throughout the body, including joint capsules, tendons, and the connective tissue surrounding joints.

Inside endometriotic lesions themselves, the inflammatory environment also stimulates the growth of new nerve fibers and blood vessels, a process that amplifies local pain signaling and can feed into the broader nervous system.³ So the disease is not just producing inflammation; it is actively rewiring pain pathways in ways that make discomfort spread.

When the Nervous System Turns Up the Volume

One of the most important reasons endometriosis causes pain far from the pelvis is a phenomenon called central sensitization. Think of it as the nervous system’s volume knob being turned up. After months or years of constant pain signals arriving from endometriotic lesions, the spinal cord and brain become more responsive to all incoming pain signals, not just those from the pelvis. A controlled study demonstrated that women with endometriosis had significantly lower pressure-pain thresholds than controls, both at areas where pelvic pain typically refers and at distant body sites that have no anatomical connection to the pelvis.⁴ In practical terms, the same amount of pressure on a knee or shoulder that a healthy person barely notices might register as painful for someone whose nervous system has been recalibrated by chronic endometriosis.

Sleep quality plays into this loop as well. Women with endometriosis report significantly poorer sleep, and research has found a direct correlation: the worse the pain, the worse the sleep, and the lower the pain threshold measured at body sites like the hip and abdomen.⁵ Poor sleep is independently known to lower pain thresholds, so the relationship feeds on itself. Joint aches that might be tolerable with good rest become grinding and persistent when sleep is disrupted night after night.

The Mast Cell and Histamine Connection

A newer area of research points to mast cells as a bridge between endometriosis and widespread pain. Mast cells are immune cells loaded with histamine and other inflammatory molecules. In endometriotic lesions, mast cells are abundant and overactive. When they release histamine, it does not just cause local inflammation; it sensitizes nerve fibers in a way that amplifies pain signaling up through the spinal cord.⁶ Animal studies have demonstrated that knocking out mast cells alleviates the heightened pain response seen in endometriosis models, and that blocking the histamine pathway reverses nerve sensitization.⁷

Serum histamine levels are significantly higher in people with endometriosis than in controls.⁸ Histamine circulating at high levels can provoke symptoms well beyond the pelvis, including joint swelling, muscle aches, and heightened sensitivity to pressure. If you have endometriosis and notice that your joint pain flares alongside other histamine-related symptoms like flushing, headaches, or gut issues, this pathway could be part of the explanation. Some clinicians have begun exploring antihistamine strategies, though this area remains early-stage.

Autoimmune Diseases That Target Joints Directly

Perhaps the most concrete link between endometriosis and joint pain is the elevated risk of autoimmune diseases that directly attack joints and connective tissue. A large case-control study comparing nearly 200,000 endometriosis patients with over 700,000 matched controls found that endometriosis roughly doubled or tripled the odds of being diagnosed with rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s syndrome, and several other autoimmune conditions within two years of an endometriosis diagnosis.⁹ The odds ratios for rheumatoid arthritis specifically ranged from about 2.3 to 2.8, meaning the risk was more than double that of the general population.¹⁰

A meta-analysis combining data from cohort studies confirmed this pattern and went further with Mendelian randomization, a genetic technique that helps distinguish true causal relationships from mere associations. The analysis found that a genetic predisposition to endometriosis was causally associated with increased risk for both systemic lupus erythematosus and rheumatoid arthritis.¹¹ This matters because rheumatoid arthritis causes painful, swollen joints, especially in the hands, wrists, and knees, while lupus and Sjögren’s syndrome can both produce joint pain alongside other symptoms. If you have endometriosis and develop persistent joint swelling, morning stiffness lasting more than 30 minutes, or symmetric pain in small joints, it is worth asking your doctor specifically about autoimmune screening rather than assuming the pain is “just” endometriosis.

Fibromyalgia and Chronic Widespread Pain

The connection between endometriosis and fibromyalgia deserves its own attention because fibromyalgia is one of the most common causes of widespread body pain, including joint pain, and endometriosis significantly raises the risk. A study tracking diagnostic records found that women with endometriosis had roughly three times the rate of later fibromyalgia diagnosis compared with women without endometriosis, and five times the rate of chronic widespread pain.¹² Fibromyalgia involves pain at many body sites, including joints, along with fatigue, sleep disturbance, and cognitive difficulties. The central sensitization described earlier is thought to be a key driver of fibromyalgia, which helps explain why the two conditions co-occur so often: years of endometriosis-driven pain signaling may push the nervous system into a state where widespread musculoskeletal pain takes hold.

Clinically, this overlap creates a diagnostic puzzle. A person with endometriosis who develops aching knees, sore shoulders, and stiff hips might have fibromyalgia, an autoimmune condition, referred pain from pelvic nerve involvement, or some combination. Sorting these out usually requires attention to the pattern: fibromyalgia pain tends to be diffuse and fluctuates with stress, sleep, and weather, while autoimmune joint pain often involves visible swelling and specific blood markers.

Can Endometriotic Tissue Actually Grow in a Joint?

Rarely, but yes. A systematic review of endometriosis affecting the skeletal and muscular system found that joints accounted for about 6% of such cases, with the rest involving abdominal muscles, pelvic floor muscles, and limb muscles.¹³ When endometriotic tissue does settle in or around a joint, it can cause pain that worsens cyclically with the menstrual cycle, a hallmark clue that the pain is endometriosis-related rather than ordinary arthritis. Reported sites include the hip, knee, and even the spine. This is a zebra diagnosis, vanishingly uncommon, but it exists and is worth considering when joint pain follows a clear menstrual pattern and standard rheumatologic workups come back negative.

Endometriosis can also involve pelvic nerves directly. MRI studies have documented endometriotic tissue encasing or compressing nerves in the pelvis, producing symptoms like pain, numbness, weakness, and in extreme cases, difficulty walking.¹⁴ When the sciatic nerve is affected, the resulting leg pain can mimic hip or knee joint problems, leading people (and sometimes their doctors) down the wrong diagnostic path.

The Hypermobility Question

You may have seen claims online that endometriosis and hypermobile Ehlers-Danlos syndrome frequently overlap, which would provide another route to joint pain. The reality is more nuanced than social media suggests. A cohort study of 386 women with hypermobile EDS found that endometriosis was diagnosed in about 6%, which is within the range for the general population and actually less than expected for women with chronic pelvic pain.¹⁵ The authors suggested that endometriosis may be over-diagnosed in hypermobile patients because chronic pain and heavy bleeding, symptoms common in EDS, prompt clinicians to suspect endometriosis. A separate review similarly concluded that the overlap between endometriosis and EDS may be less common than previously thought.¹⁶ That said, if you are hypermobile and have endometriosis, the joint pain you experience likely has contributions from both conditions, and sorting out which is causing what can be genuinely difficult.

Leg Pain, Laparoscopy, and What Surgery Can and Cannot Fix

Cyclic leg pain is common enough in endometriosis to have been studied specifically. A study comparing leg pain in women with confirmed endometriosis versus controls found that laparoscopic surgery improved leg pain intensity in both groups, but the difference in improvement between the endometriosis group and the control group was not statistically significant.¹⁷ This suggests that while removing endometriotic lesions may help pelvic pain, the widespread musculoskeletal pain that many patients experience is driven by systemic processes — inflammation, central sensitization, mast cell activation — that persist even after lesions are excised. It is one of the more frustrating aspects of the disease: surgery can be transformative for localized symptoms but may not address the body-wide pain amplification that has already taken root.

Hormonal treatments used for endometriosis can also have musculoskeletal side effects of their own. GnRH antagonists, a newer class of drugs used to suppress the hormonal fuel for endometriotic tissue, carry dose-dependent risks of bone mineral density loss.¹⁸ When bone density drops, joint pain can worsen, and the risk of stress fractures rises. Hot flashes and headaches are the most common side effects of these medications, but the bone-density issue is particularly relevant for someone already dealing with joint pain, because it can muddy the picture further.

Approaches That Address the Whole Pattern

Because joint pain in endometriosis usually stems from systemic processes rather than local joint damage, management strategies that address the nervous system and inflammation broadly tend to be more helpful than treating one joint at a time. A network meta-analysis of non-drug interventions for endometriosis-related pain found that physical therapy ranked highest for reducing overall pain, followed by acupuncture and psychological interventions. All three were significantly better than standard care alone, and both physical therapy and acupuncture also improved quality of life substantially.¹⁹ Physical therapy here does not mean generic stretching; it typically involves pelvic floor work, graded exercise, and manual therapy aimed at both pelvic and extra-pelvic pain areas.

For people whose joint pain is driven by an autoimmune condition diagnosed alongside endometriosis, disease-specific treatment — such as disease-modifying drugs for rheumatoid arthritis — can make a dramatic difference. The key is identifying the autoimmune component rather than attributing all symptoms to endometriosis and stopping there. Similarly, if fibromyalgia is part of the picture, medications and behavioral strategies specifically targeting central sensitization (exercise, sleep hygiene, certain classes of antidepressants) tend to help more than anti-inflammatories alone.

The Gut Microbiome and Systemic Inflammation

An emerging area of research explores whether disruption of the gut microbiome in endometriosis contributes to the chronic inflammatory state that drives distant symptoms, including joint pain. Dysbiosis — an imbalance in gut bacterial communities — has been documented in people with endometriosis, and proposed mechanisms include impaired gut barrier function leading to increased immune activation, altered estrogen metabolism, and elevated proinflammatory cytokines.²⁰ This is still early-stage science, and no one should be taking specific probiotics expecting their joint pain to resolve. But it highlights how endometriosis is increasingly understood not as a localized pelvic disease but as a systemic condition with immunological ripple effects that can reach joints, muscles, and connective tissue throughout the body. That broader framing is likely the most useful takeaway for anyone trying to understand why their endometriosis seems to hurt everywhere, not just where the lesions are.