Orthostatic intolerance and ME/CFS
Orthostatic intolerance (OI) means symptoms worsen when upright — sitting or standing — and improve when lying flat. It affects most people with ME/CFS, and under NICE NG206 it is one of two symptoms, alongside cognitive impairment, that can satisfy the fourth diagnostic criterion.
For some people, OI is the most disabling feature of the illness — the reason sitting up, working at a desk, or queuing for ten minutes is impossible. For others it is one symptom among many.
What orthostatic intolerance feels like
OI is not the same as feeling dizzy when standing up too quickly. It is a persistent intolerance of being upright. Common signs include:
- Lightheadedness or dizziness that does not pass after a few seconds.
- A racing or pounding heart on standing.
- Nausea, sometimes severe.
- Weakness in the legs, or a sense of needing to sit or lie down urgently.
- Pain across the upper back and base of the neck — sometimes called “coathanger” pain.
- Visual changes — greying out, tunnel vision, flickering.
- Worsening brain fog when upright that lifts on lying down.
- In some cases, fainting.
Symptoms can come on within minutes of standing, or build slowly over half an hour or more. They tend to be worse first thing in the morning, after hot showers, after meals, and in warm rooms.
Related conditions
Orthostatic intolerance is an umbrella term. Two specific conditions sit underneath it and are commonly diagnosed alongside ME/CFS.
Postural tachycardia syndrome (POTS)
A heart-rate increase of 30 beats per minute or more within 10 minutes of standing — 40 in teenagers — without a corresponding drop in blood pressure. POTS is increasingly recognised in ME/CFS and Long Covid populations.
Neurally-mediated hypotension (NMH)
A drop in blood pressure when upright, sometimes leading to fainting. Less commonly diagnosed than POTS, but can occur in ME/CFS.
What may help
Most management of OI in ME/CFS is non-medical and focused on reducing the load on the autonomic nervous system.
Daily habits
- More salt and fluid. Around two to three litres of water a day, with additional salt at meals, can help expand blood volume. Check with a GP first if you have high blood pressure or kidney problems.
- Compression garments. Waist-high compression tights (20 to 30 mmHg) are more effective than knee-highs at reducing blood pooling.
- Head-of-bed elevation. Raising the head of the bed by 10 to 15 cm can ease morning symptoms.
- Slow position changes. Sitting on the edge of the bed for a minute before standing, and pausing again before walking.
Adapting daily life
- Recline rather than sit upright. A reclining chair or sofa with feet up shifts load off the autonomic system without lying flat.
- Sit to do tasks. Showering, cooking, brushing teeth — anywhere standing can be replaced with sitting, it helps.
- Avoid prolonged standing. Queues, public transport, and standing-only events are common triggers.
Medications such as fludrocortisone, midodrine, ivabradine, or beta blockers are sometimes prescribed for POTS or significant OI. These need specialist input and are not first-line for everyone.
When to push for further assessment
If standing or sitting upright reliably worsens your symptoms — particularly where a racing heart, fainting, or persistent lightheadedness are part of the picture — it is worth raising orthostatic intolerance with your GP directly. A NASA Lean Test, a referral to cardiology, or a tilt table test may be appropriate.
OI is treatable in ways that some other ME/CFS symptoms are not. Identifying it specifically often opens up management options that broader fatigue management does not.
Related pages
ME/CFS symptoms — the main symptoms explained in plain language.
How ME/CFS is diagnosed — what doctors look for, including OI assessment.
Managing ME/CFS — pacing, radical rest, and symptom management.
Severity levels — how OI tends to worsen at moderate to severe levels.