Orthostatic intolerance and ME/CFS

Orthostatic intolerance (OI) means symptoms worsen when upright, whether sitting or standing, and ease when lying flat.

It affects most people with ME/CFS. Under NICE NG206 it is listed among the associated symptoms that support suspicion and assessment, rather than one of the four core diagnostic criteria.

For some people, OI is the most disabling feature of the illness. Sitting up, working at a desk, or queuing for ten minutes is impossible.

For others, it is one symptom among many.

Orthostatic intolerance (OI) is not the same as feeling dizzy when standing up too quickly. It is a persistent intolerance of being upright.

• 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 such as greying out, tunnel vision, or 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.

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, or 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 it can occur in ME/CFS.

Getting a diagnosis

A formal diagnosis usually involves a tilt table test, where heart rate and blood pressure are monitored during a controlled period of being upright.

The NASA Lean Test is a simpler version that can be done in a GP surgery, and it provides useful evidence.

The autonomic nervous system controls heart rate, blood pressure, and blood flow without conscious input.

Research suggests this system does not respond properly to changes in posture in ME/CFS. Blood pools in the legs, the heart compensates inadequately, and the brain receives less blood than it needs.

The result is a body that can lie down, but cannot reliably stand.

Most management of OI in ME/CFS is non-medical.

It focuses on reducing the load on the autonomic nervous system, through daily habits and through adapting how tasks get done.

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 down 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.

Medication options

Medications are sometimes prescribed for POTS or significant OI. Fludrocortisone, midodrine, ivabradine, and beta blockers are the most common.

These need specialist input, and they are not first-line for everyone.

If standing or sitting upright reliably worsens your symptoms, it is worth raising orthostatic intolerance with your GP directly.

This matters particularly where a racing heart, fainting, or persistent lightheadedness are part of the picture. 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.