Four conditions. Four different sets of symptoms. Four completely different mechanisms — or so the research initially suggested.
And yet: they travel together. People with POTS often have ME/CFS. People with ME/CFS often have fibromyalgia. MCAS frequently appears alongside all three. Researchers are increasingly convinced they're looking at overlapping expressions of a common underlying dysfunction, rather than four separate conditions that happen to co-occur.
Here is what each one actually is, why each one is so frequently missed, and what that means for the people living with them.
POTS: Postural Orthostatic Tachycardia Syndrome
POTS is a form of dysautonomia — a dysfunction of the autonomic nervous system, which regulates heart rate, blood pressure, digestion, and dozens of other automatic processes. In POTS, the autonomic system fails to adequately compensate when the body moves from lying to standing. The heart rate accelerates abnormally — typically by 30 beats per minute or more within ten minutes of standing — while blood pressure may or may not drop.
The result: dizziness, near-fainting, heart pounding, extreme fatigue, brain fog, and a host of secondary symptoms. It can make standing in a queue — standing at all — profoundly difficult.
POTS is most commonly diagnosed in women between 15 and 50. The average time to diagnosis is several years. It is still not routinely tested for in primary care, often attributed to anxiety, and significantly undertreated even after diagnosis.
ME/CFS: Myalgic Encephalomyelitis / Chronic Fatigue Syndrome
ME/CFS is a complex, multi-system illness characterised primarily by post-exertional malaise (PEM): a worsening of symptoms that follows exertion — physical, cognitive, or emotional — which is not proportional to the effort expended and is not relieved by rest.
The name "chronic fatigue syndrome" is widely regarded as a poor descriptor that contributes to the trivialisation of the condition. "Fatigue" implies tiredness. ME/CFS produces a profound, systemic impairment that extends across neurological, immune, autonomic, and metabolic systems. Patients who are severely affected may be unable to leave their beds or tolerate light and sound.
ME/CFS affects an estimated 17-24 million people in the US alone. It remains without an approved treatment in most countries, and has historically received dramatically less research funding than conditions of comparable prevalence and severity.
Fibromyalgia
Fibromyalgia is a condition characterised by widespread musculoskeletal pain, fatigue, sleep disturbance, and cognitive difficulties. It is understood to involve altered pain processing — the brain and nervous system amplify pain signals, a phenomenon called central sensitisation.
Because fibromyalgia does not produce measurable tissue damage and tests typically return normal results, it was long classified as a psychiatric condition or attributed to somatisation. That classification is now regarded as incorrect — fibromyalgia is a neurological condition with identifiable pathophysiology — but the cultural residue remains. People with fibromyalgia are still frequently told their symptoms are psychosomatic.
MCAS: Mast Cell Activation Syndrome
Mast cells are immune cells involved in allergic response and defence against pathogens. In MCAS, mast cells activate inappropriately and release chemical mediators — histamine, tryptase, and others — in response to triggers that should not normally cause a response. These triggers can include food, temperature changes, emotional stress, medications, and infections.
The symptoms of MCAS are wide-ranging — affecting the skin, gut, cardiovascular system, neurological system, and respiratory system — which makes it particularly difficult to recognise. It is frequently mistaken for allergies, irritable bowel syndrome, anxiety, or idiopathic (unknown cause) symptoms.
Why these conditions are so often missed
All four conditions share a set of diagnostic challenges: they present with normal standard tests, they are highly variable (symptoms change day to day and person to person), and they are disproportionately diagnosed in women — a demographic whose pain and symptom reports have been historically undertreated in medicine.
They also require specialist knowledge that is unevenly distributed. A general practitioner who is not familiar with POTS may not know to do a ten-minute standing heart rate test. A cardiologist focused on structural heart disease may not think to investigate dysautonomia. The conditions fall between specialties, and patients spend years being referred between departments without anyone connecting the picture.
“The problem isn't just that these conditions are hard to diagnose. It's that the system isn't looking for them.”
Living with one (or more) of these conditions
Many people who have one of these conditions have two or three. The day-to-day reality involves managing unpredictable symptoms, navigating a medical system that is often dismissive, and trying to maintain a life — career, relationships, identity — around an illness that most people around them cannot see.
This is not a small thing. And it is not a personal failure. These are real, complex, systemic conditions. Getting a diagnosis is not a starting line — it's often just the end of one long fight and the beginning of another.
Spooniversity was built by Roi Shternin, who has POTS, ME/CFS, fibromyalgia, MCAS, and CPTSD. It's designed around the reality of living with these conditions — not around the theoretical good day.