ME/CFS vs POTS: How Do They Differ, and Can You Have Both?

What's the Difference Between ME/CFS and POTS?

POTS is a sustained heart rate rise of 30 or more beats per minute within 10 minutes of standing (40 or more in teens), with symptoms and no drop in blood pressure. ME/CFS is diagnosed from symptoms: profound fatigue, post-exertional malaise (a crash that often comes a day or more after effort), unrefreshing sleep, and trouble thinking or being upright. POTS is defined by what your heart does when you stand. ME/CFS is defined by how you feel, including after effort.

Because ME/CFS is a name for how you feel, it doesn't say what's driving it, so our team looks for the mechanism underneath the label.

The same trouble standing can happen without the fast heart rate. When brain blood flow falls with normal heart rate and blood pressure, it's called OCHOS, and when low CO2 drives it, HYCH (Novak, 2024).

On a standard tilt, heart rate is where the 2 usually look different. In many orthostatic intolerance syndromes, including ME/CFS and long COVID, heart rate and blood pressure are frequently normal despite significant drops in brain blood flow (Khan, 2025). Our team sees the fast heart rate in POTS as a compensation that keeps blood moving to the brain, which makes POTS the compensation succeeding.

Can You Have ME/CFS and POTS at the Same Time?

Orthostatic intolerance is common in ME/CFS and may worsen daily functioning (Yamazaki, 2026). A 2026 review says the majority of people with ME/CFS have it, and that it's the main thing limiting their daily function (Miwa, 2026).

Studies that tested people directly give more specific numbers. In 49 adults with ME/CFS who did a 10-minute lean test with capnography, 55.1% had at least 1 abnormality. The most common was POSH (40.8%), the postural orthostatic syndrome of hypocapnia, which the study defined as normal CO2 lying down with any leaning value below 34 mmHg (Yamazaki, 2026).

In a 2026 study of 170 adults with ME/CFS referred for autonomic testing, 19% met POTS criteria, while 88% had reduced brain blood flow when upright (Novak, 2026). Those were patients referred to an autonomic lab, so the rates are likely higher than in ME/CFS overall.

55.1%of 49 adults with ME/CFS had at least 1 lean-test abnormalityYamazaki, 2026

40.8%had POSH, low CO2 on leaning, the most common abnormalityYamazaki, 2026

7 of 18adolescents with ME/CFS were diagnosed with POTS, against 0 of 18 healthy controlsLeone, 2026

19%of 170 adults with ME/CFS referred for autonomic testing met POTS criteria, while 88% had reduced brain blood flow uprightNovak, 2026

The adolescent study compared 18 teenagers with ME/CFS to 18 matched healthy controls. In interviews, 15 of the 18 with ME/CFS (83%) reported a history of orthostatic intolerance, against 3 of the 18 controls (17%) (Leone, 2026). Both studies are small, and they show the 2 conditions occurring together without saying which comes first.

Blood volume didn't explain the lean-test findings. In the 49 adults above, static blood-volume categories weren't associated with lean-test abnormalities, which the authors read as a sign of autonomic, vascular, respiratory or cerebrovascular contributions (Yamazaki, 2026). The volume question has its own page: Is IV Saline the Cure for ME/CFS and Dysautonomia?

Why Can a Tilt Test Look Normal in ME/CFS?

A standard tilt records heart rate and blood pressure and uses them as stand-ins for brain blood flow (Khan, 2025), and in our team's experience heart rate gets most of the attention. When both stay normal while brain blood flow falls, that "often leads to the incorrect conclusion that there is nothing hemodynamically abnormal in these patients" (Khan, 2025). We compare the 2 patterns on POTS vs OCHOS.

POTS pattern Compare both

Replay

A 2025 systematic review of 118 articles found brain blood flow significantly reduced versus controls in 12 of the 26 that studied ME/CFS alone. In 4 of 11 studies that looked at both, flow was lower still in people with ME/CFS and orthostatic intolerance, and the authors warn that orthostatic intolerance may explain part of the drop seen in ME/CFS studies (Christopoulos, 2025).

Our team's approach to long COVID is on the long COVID treatment page.

Are ME/CFS and POTS the Same Problem?

A 2026 study ran the same autonomic tests on people with ME/CFS and people with long COVID. Brain blood flow dropped on standing in 88% of the ME/CFS group, and only 19% met the criteria for POTS. Long COVID looked almost the same, at 92% and 22% (Novak, 2026). That puts the common thread at brain blood flow, and POTS is the form it takes in about 1 in 5.

An earlier paper placed POTS and HYCH on 1 spectrum of the same disorder, though it didn't include ME/CFS (Novak, 2024).

POTSHYCH

• Reduced orthostatic brain blood flow
• Hypocapnia
• Mild autonomic failure
• Small fiber neuropathy

Our team's position is that the label you leave with matters less than the mechanism you measure, because 2 people with the same label can have different drivers, and 2 different labels can share one.

What Does Our Team Measure on a Tilt?

The clinic starts from the mechanism behind the symptoms. For someone with a fatigue diagnosis, 2 tests our team looks at right away are transcranial Doppler on a tilt, which follows blood flow speed in the brain's arteries, and end-tidal capnography, which measures the CO2 at the end of each breath.

Brain blood vessels respond to CO2: high CO2 widens them and low CO2 narrows them, so less blood reaches the brain (more on CO2 and brain blood flow). In the video below, a patient recovering from post-viral dysautonomia has a heart rate rise too small to qualify as POTS, and the capnography trace shows CO2 running low through the tilt.

When the picture points elsewhere, the team checks other systems. For post-concussion symptoms, that means vestibular function, eye movements, reflexes and cognition. For suspected craniocervical instability (CCI), a dynamic motion X-ray (DMX) can reproduce symptoms, and CCI can be measured in a way a symptom cluster can't.

The principle is to provoke the system and see which mechanism reproduces your symptoms, instead of counting how many checklist boxes you meet. Heart rate and blood volume medications can ease POTS symptoms and serve as a bridge, and they have a ceiling, and the mechanism underneath is what we look for.

ME/CFS vs POTS: FAQ

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