How EDS, POTS & MCAS Are Connected
Updated: Oct 15
If you've been diagnosed with Ehlers-Danlos syndrome (EDS), postural orthostatic tachycardia syndrome (POTS) or mast cell activation syndrome (MCAS), you may have heard that the three often travel together. Some of that is well supported by research. Some of it is still debated. Here's what we know, what we don't & why it matters for your care.
A Quick Look at Each Condition
Ehlers-Danlos syndrome (EDS)
The Ehlers-Danlos syndromes are a group of inherited connective tissue disorders. There are 13 types, and hypermobile EDS (hEDS) is by far the most common. Connective tissue supports your skin, joints, blood vessels & organs, so EDS can affect the whole body. There's no genetic test for hEDS yet; diagnosis is clinical, based on established criteria.
POTS
POTS is a form of dysautonomia, a disorder of the nervous system that runs automatic functions like heart rate & blood pressure. With POTS, your heart rate rises sharply when you stand: by 30 beats per minute or more in adults (40 or more for patients under 19) within 10 minutes, without a drop in blood pressure. Common symptoms include dizziness, a racing heart, fatigue & brain fog.
MCAS
Mast cells are part of your immune system. With MCAS, they release chemicals like histamine too easily, causing repeated episodes of symptoms in two or more body systems, such as flushing, hives, cramping, low blood pressure or wheezing. MCAS is different from systemic mastocytosis & from histamine intolerance.
What the Research Says About the Overlap
EDS & POTS: the strongest link. The connection between hypermobile EDS & POTS is the best established of the three. A review in the Cleveland Clinic Journal of Medicine describes a strong overlap between the two, and the Ehlers-Danlos Society notes that dysautonomia is among the conditions often seen in people with EDS.
MCAS: still debated. This is where experts disagree.
The Ehlers-Danlos Society lists mast cell diseases among the conditions often seen in people with EDS.
Cleveland Clinic takes the opposite view, listing "linked to conditions like POTS or EDS" among common misconceptions about MCAS. It also describes MCAS as believed to be rare & warns that overdiagnosis can delay finding the true cause of symptoms.
The Cleveland Clinic Journal of Medicine review calls the relationship between mast cell activation & POTS poorly understood.
Why the numbers vary so much. A 2025 study in Frontiers in Neurology looked at 100 young patients with POTS. How many also had MCAS depended almost entirely on which diagnostic criteria were used: 2% under the strictest criteria, 37% under a more moderate standard & 87% using clinical criteria. Hypermobility rates shifted the same way, from 13% to 34%.
In other words, part of the disagreement comes down to definitions. That's why a careful, evidence-based workup matters more than a label.
Why This Matters for Your Care
Whether or not researchers settle the debate, many patients live with symptoms from more than one of these conditions at once. That creates real challenges:
Symptoms overlap, so it's hard to tell which condition is causing what
Care gets split across rheumatology, cardiology, neurology, allergy & GI, with no one connecting the dots
Patients often spend years searching for answers
A treatment for one condition can affect another
What helps most is a physician who knows all three conditions, takes the time to sort through overlapping symptoms & coordinates with your specialists.
How PICM Can Help
At Phoenix Integrative Concierge Medicine, our physicians bring added focus to Ehlers-Danlos syndrome, POTS & MCAS within full-service concierge primary care. Extended visits give us time to review your full history, and we coordinate with your specialists so your care works as one plan.
Frequently Asked Questions
If I have EDS, will I develop POTS or MCAS?
Not necessarily. The conditions often appear together, but having one doesn't mean you'll develop the others.
Can one doctor manage all three conditions?
A primary care physician can coordinate your care across all three & manage much of the day-to-day. You'll likely still see specialists for testing or specific treatments, and your physician helps keep everyone on the same page.
How is MCAS diagnosed?
MCAS can't be diagnosed from symptoms alone. Diagnosis generally requires repeated symptoms in two or more body systems, lab evidence of mast cell activation during a flare & improvement with mast cell-targeted treatment.
Have Questions?
If you're living with EDS, POTS or MCAS & want a physician who sees the whole picture, we'd love to talk. Schedule an intro call to learn more about PICM.
Sources
This article is for general information & isn't medical advice. Talk with your doctor about your specific situation.
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