For years, sufferers of postural orthostatic tachycardia syndrome (POTS) and related forms of orthostatic intolerance (OI) were told it was “all in their head.” But growing evidence shows these are real, often disabling conditions rooted in the body’s nervous system, blood volume, and sometimes the immune system.
Standing Up Shouldn’t Hurt
When we stand, gravity pulls blood toward the legs. In a healthy person, the autonomic nervous system constricts blood vessels and keeps blood flowing to the brain. In people with POTS, this system falters. Blood pools in the lower body. The heart races to compensate. And dizziness, palpitations, nausea and fatigue follow.
It is not anxiety. It is measurable physiology and it can be life-changing.
What It Looks Like
Patients often describe:
- Light-headedness or near-fainting on standing
- Rapid heartbeat or palpitations
- Fatigue and “brain fog”
- Headaches or migraines
- Gastrointestinal issues such as nausea, bloating, constipation or diarrhoea
- Temperature swings and sweating abnormalities
- Trembling or shakiness
- Sleep disturbance and anxiety-like symptoms (usually secondary)
Why It Happens
POTS is not a single disease. It is a syndrome with several overlapping mechanisms:
- Neuropathic POTS damage to small autonomic nerve fibres in the legs prevents proper blood vessel constriction.
- Hypovolaemic POTS low blood volume; adding salt and fluids often helps.
- Hyperadrenergic POTS the sympathetic nervous system overreacts, causing palpitations, tremor, and anxiety-like surges.
- Autoimmune mechanisms antibodies targeting muscarinic or adrenergic receptors may disrupt blood pressure and heart rate regulation.
- Deconditioning prolonged inactivity or illness weakens the heart and blood vessels’ ability to respond to standing.
Often, more than one mechanism is at play.
Comorbidities and Autoimmune Connections
POTS rarely exists in isolation. Recognising associated conditions can guide treatment:
- Hypermobility spectrum / Ehlers–Danlos syndrome (hEDS): Loose connective tissue can worsen blood pooling.
- Mast cell activation syndrome (MCAS): Flushing, rashes, and digestive symptoms often overlap.
- Small-fibre neuropathy: Can cause burning pain, abnormal sweating, and autonomic symptoms.
- Sjögren’s syndrome: This autoimmune disorder, better known for dry eyes and mouth, frequently affects autonomic nerves. Patients may develop dizziness, palpitations, and fatigue even before classic dryness appears.
- Systemic lupus erythematosus (SLE): Lupus can disrupt autonomic function through autoantibodies or nerve damage. Orthostatic symptoms may worsen during flares.
- Chronic fatigue syndrome / ME and long COVID: Post-viral autonomic dysfunction often mimics or overlaps with POTS.
How It’s Diagnosed
GPs can screen for POTS using a simple active stand test:
- Rest lying down for 5–10 minutes, measuring heart rate and blood pressure.
- Stand and record immediately, then at 1, 3, 5, and 10 minutes.
- Diagnostic threshold: Heart rate increase ≥30 bpm in adults (≥40 bpm in teenagers), without a significant blood pressure drop.
Specialist tests may include tilt-table testing, heart-rate variability, QSART, plasma catecholamines, skin biopsy for small-fibre neuropathy, and autoimmune panels.
Managing POTS
There is no universal cure, but most patients benefit from a combination of lifestyle measures and, where appropriate, medication:
Lifestyle first:
- Drink 2–3 litres of water daily
- Increase salt intake under supervision
- Use compression garments
- Avoid prolonged standing, heat, and large meals
- Elevate the head of the bed slightly
- Gradually build up exercise, starting with recumbent activities
Medications, used carefully: Fludrocortisone, midodrine, low-dose beta-blockers, ivabradine, pyridostigmine, clonidine, or antihistamines for MCAS. Immunotherapy may help in autoimmune cases such as Sjögren’s or lupus under specialist guidance.
Outlook
With proper recognition and management, some patients improve over a few years. Some remain symptomatic but can lead functional lives with careful pacing and treatment. Early diagnosis avoids years of misattribution to anxiety or stress.
Bottom Line
POTS and orthostatic intolerance are real, measurable, and treatable. They sit at the intersection of neurology, rheumatology, and immunology. For patients, understanding their condition is empowering. For clinicians, believing the symptoms and measuring heart rate and blood pressure can make all the difference.
Disclaimer
This article is for information and awareness only. It is not medical advice and should not replace professional assessment or treatment. Always consult a qualified healthcare professional before making changes to your medication, salt or fluid intake, exercise routine, or management plan. If you experience fainting, chest pain, severe dizziness, or other urgent symptoms, seek medical help immediately.
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