Chronic fatigue syndrome (ME/CFS):
we start with symptoms that worsen after activity
If fatigue lasts a long time after going out or working, or your head feels foggy or standing is hard, we look at how the symptoms started and how they worsen and recover.
If this is a follow-up visit or you'd like to give more detail, please fill out the detailed questionnaire.
Chronic fatigue and ME/CFS evaluation: three things to know first
Persistent fatigue has many causes
Many causes can lead to fatigue, including anemia, thyroid disease, sleep disorders, depression or anxiety, post-infectious conditions, medication side effects, and nutritional deficiencies. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is one diagnosis among them; not all long-lasting fatigue is ME/CFS. The name is historical and does not mean that inflammation of the brain and spinal cord has been confirmed in any individual patient.
We look at post-exertional worsening, sleep, cognition, and orthostatic symptoms together
In an ME/CFS evaluation, we check whether daily functioning has clearly declined, whether symptoms worsen after activity (PEM), whether sleep is unrefreshing, whether concentration and memory are difficult, and whether symptoms appear when standing. Both the 2015 Institute of Medicine (IOM) criteria presented by the U.S. Centers for Disease Control and Prevention (CDC) and the guideline of the UK National Institute for Health and Care Excellence (NICE) center evaluation on these symptoms.
There is no single confirmatory test, so we judge comprehensively
There is currently no test that confirms or rules out ME/CFS on its own. So we judge by putting together your history and symptom course, examination, tests to rule out other causes, and evaluation of coexisting problems. We do not dismiss your symptoms just because previous test results were normal.
Do you have these symptoms?
We have written down, as they are, expressions patients often use in the clinic. The number of items that apply is not used to judge diagnosis or severity; we check them together with your course at the visit.
Fatigue and symptoms that get worse after activity
"The day after I go out, I can't get up at all." "After a single meeting, I'm in bed for two days."After physical or mental activity that used to be no problem, not only fatigue but also pain, fogginess, and flu-like symptoms worsen together, and that state continues.
Sleep that doesn't refresh you even when you sleep enough
"Even after 8 hours of sleep, I feel like I stayed up all night." "I can fall asleep, but mornings are the hardest."You don't feel recovered after sleeping even though you sleep enough hours. We also check whether there are accompanying sleep problems such as difficulty falling asleep, frequent waking, or snoring and apnea.
Brain fog: difficulty concentrating, remembering, and organizing thoughts
"Words won't come to me." "I read, but nothing goes in."Your head feels foggy, and sustaining concentration, remembering, and organizing thoughts into speech or writing have become harder than before. It often worsens together when activity or fatigue increases.
Dizziness or palpitations when standing
"If I stand in line, I break into a cold sweat and everything goes dark." "I only feel okay when I'm lying down."When standing or sitting for a long time, you get dizziness, palpitations, nausea, or blurred vision, which improve when you lie down or sit. Coexisting problems such as postural orthostatic tachycardia syndrome (POTS) or orthostatic hypotension may need to be checked. If orthostatic symptoms are prominent, you can read more on the POTS information page.
A timeline for understanding post-exertional malaise (PEM)
Post-exertional malaise (PEM) is a worsening of symptoms that can appear not only after physical activity but also after cognitive or emotional activity such as concentrating, talking, or emotional strain. It may appear right after the activity or some time later, and how long the worsening lasts differs from person to person.
Activities that used to be manageable, such as walking, going out, work, conversation, or screen time
Fatigue, pain, fogginess, sore throat or flu-like feelings, or worse sleep appear or intensify
A period when you can't do what you usually can. It may be short or may continue for a long time
The return to your previous state. Sometimes you don't fully return, so keeping records matters
Four questions worth remembering before your visit
- What activity did you do?
- When did the worsening start?
- Which symptoms got worse?
- How long did it take to recover?
What we look at in ordinary fatigue versus an ME/CFS evaluation
The table below explains what we look at differently at the visit. You cannot diagnose yourself from the table alone; each item is interpreted together with your history, examination, and tests.
| Item | Ordinary fatigue | What an ME/CFS evaluation checks |
|---|---|---|
| Duration and change in daily functioning | The cause, such as overwork, lack of sleep, or stress, is relatively clear, and daily functioning tends to recover once the cause is resolved. | We check whether functioning has clearly declined to the point that it is hard to keep up previous work, study, or social activities. The 2015 IOM criteria presented by the CDC look at whether this state has lasted 6 months or longer. |
| Change after rest | It generally improves with enough rest or sleep. | We check whether the fatigue does not clearly improve with rest or sleep. |
| Post-exertional worsening | You may be tired right after activity, but daily activities are generally possible the next day. | We check whether multiple symptoms worsen together and persist after activity that used to be no problem (PEM), and when it begins and how long recovery takes. |
| Sleep | When lack of sleep is the cause, catching up on sleep brings recovery. | We check whether sleep is unrefreshing even when you sleep enough hours, and whether there are accompanying sleep problems (insomnia, apnea, etc.). |
| Cognitive and orthostatic symptoms | Temporary difficulty concentrating can occur, but symptoms when standing tend not to be prominent. | We check whether at least one of brain fog (difficulty concentrating, remembering, and organizing thoughts) or dizziness and palpitations on standing (orthostatic intolerance) is present. |
| Diagnostic approach | We find and correct the lifestyle factors or conditions causing it. | There is no single confirmatory test, so we combine history, examination, necessary tests to rule out other causes, and evaluation of coexisting problems. Even if tests are normal, we do not deny the symptoms themselves. |
The duration criterion follows the 2015 Institute of Medicine (IOM) diagnostic criteria presented by the U.S. Centers for Disease Control and Prevention (CDC). The UK NICE guideline (NG206) uses different criteria, such as reviewing the diagnosis 3 months after symptoms begin, so this page does not mix the two.
How we evaluate chronic fatigue and ME/CFS at our clinic
Drawing on experience in ENT care and in evaluating autonomic and orthostatic symptoms, Yonsei DANA ENT Clinic looks at the symptom patterns and coexisting problems of patients with chronic fatigue. The order below is the general flow, and tests are decided within the necessary scope according to each patient's condition.
Checking onset, infection history, previous tests, and medications
We check when and how the symptoms started (including whether they began after an infection), the results of tests you have had, and the medications and supplements you currently take.
Checking changes before and after activity, and sleep, cognitive, and orthostatic symptoms
We organize in time order how symptoms change after activity, how refreshed you feel after sleep, changes in concentration and memory, and symptoms when standing.
Examination, and review of needed differential tests and autonomic evaluation
Including an ENT examination, we review whether more tests are needed to rule out other causes, and when needed we perform blood pressure and pulse evaluation on standing and heart rate variability (HRV) evaluation.
Explaining results, individual management, and a follow-up plan
We explain what was found, decide on activity–rest adjustment and how to manage coexisting problems, and follow your course together. If evaluation by another department is needed, we will guide you.
Fill out the pre-visit symptom questionnaire (short form)
The scope of testing is decided by each patient's condition. Even if you have been tested elsewhere, all tests needed for our evaluation are done at our clinic, and previous results are reviewed as reference material for comparing your course.
What tests can show, and their limits
The items used in an ME/CFS evaluation each have a different purpose, and none of them confirms a diagnosis on its own. Knowing the limits of interpretation helps you understand the results.
| Evaluation item | Purpose | Limits of interpretation |
|---|---|---|
| History, symptom, and daily-function evaluation Done at our clinic | We check how symptoms began and progressed, the pattern of post-exertional worsening, and how much daily functioning has declined. This is the central step of an ME/CFS evaluation. | It depends on memory, so accuracy drops without records. Activity and symptom logs before your visit help a great deal. |
| Review of previous blood tests and necessary differential tests Done at our clinic | We rule out other causes of fatigue, such as anemia, thyroid dysfunction, liver and kidney function, inflammation, blood sugar, and nutritional status. | A normal result means other causes are less likely; it does not confirm or rule out ME/CFS. We do not deny your symptoms just because previous tests were normal. |
| Blood pressure and pulse evaluation on standing Done at our clinic | We check how blood pressure and pulse change after standing up from lying down, looking for coexisting problems such as postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension . | Results can vary with hydration, medications, meals, and time of day on the day of measurement, so we do not draw conclusions from a single measurement. |
| Heart rate variability (HRV) evaluation Done at our clinic | We measure changes in the intervals between heartbeats as a reference for the state of autonomic function. It is used to look at coexisting autonomic problems and to compare your course. Measurement methods and preparation are described in Autonomic testing information. | HRV alone does not confirm or rule out ME/CFS. HRV is affected by many factors, including breathing, posture, time of measurement, medications, sleep, and caffeine. |
| Review of sleep, nutrition, and accompanying symptoms Done at our clinic | We check problems that need to be managed together, such as sleep problems, nutritional deficiencies, digestive symptoms, pain, and mood changes. | When needed, additional tests at other institutions, such as polysomnography, or evaluation by other departments may be required. |
"Done at our clinic" means an evaluation actually performed in our clinic's care; whether it is done depends on the patient's condition and previous results.
Management after evaluation
There is currently no established treatment that cures ME/CFS. So management focuses on reducing post-exertional worsening and protecting daily functioning by addressing confirmed coexisting problems one at a time.
Activity–rest adjustment that respects your individual limits
We find the range in which symptoms do not worsen after activity and decide together how to distribute activity and rest within it (pacing). It is neither resting no matter what nor steadily increasing a fixed amount of exercise. The NICE guideline does not recommend increasing exercise in fixed steps.
Managing sleep and accompanying symptoms
We review sleep rhythm and sleep environment, and check and manage accompanying symptoms such as pain, headache, and digestive symptoms individually. If a separate condition such as sleep apnea is suspected, we guide you to the appropriate test.
An individual approach to confirmed problems such as orthostatic intolerance
If POTS or orthostatic hypotension is confirmed in the blood pressure and pulse evaluation on standing, we individually manage that problem, for example with fluid and salt intake, posture adjustment, compression stockings, and medication when needed.
Evaluating and managing confirmed nutritional deficiencies or other conditions
If tests reveal deficiencies such as iron, vitamin D, or vitamin B12, or another cause such as thyroid disease, we correct that problem first. If evaluation by another department is needed, we will guide you.
How our clinic's other treatments relate to ME/CFS
Our clinic performs epipharyngeal abrasive therapy (EAT), repetitive transcranial magnetic stimulation (rTMS), nutrient injections, and other treatments for other conditions such as chronic epipharyngitis and tinnitus. These are not established treatments or cures for ME/CFS, and we do not present effects seen in other conditions as effects on ME/CFS.
We discuss them separately only when a condition that these treatments are indicated for, such as chronic epipharyngitis or tinnitus, is also confirmed in a patient with chronic fatigue, and even then we explain the indications, current evidence, and limitations separately.
Frequently asked questions about chronic fatigue and ME/CFS care
Are chronic fatigue and chronic fatigue syndrome the same?
No. "Chronic fatigue" refers to the symptom of long-lasting fatigue, while "chronic fatigue syndrome (ME/CFS)" is a diagnosis given when post-exertional worsening, unrefreshing sleep, cognitive or orthostatic symptoms, and a clear decline in functioning continue for a certain period.
Long-lasting fatigue can also come from other causes such as anemia, thyroid disease, sleep disorders, depression or anxiety, or medication side effects, so having chronic fatigue does not mean it is ME/CFS.
If ME/CFS is suspected, which department should I see?
There is no single designated department; you can start where other causes of fatigue can be ruled out and accompanying symptoms can be looked at together. In Korea, family medicine, internal medicine, and neurology departments see these patients, and if dizziness, orthostatic symptoms, or sleep problems are prominent, a clinic that can perform autonomic evaluation is helpful.
Drawing on experience in ENT care and in evaluating autonomic and orthostatic symptoms, Yonsei DANA ENT Clinic looks at the symptom patterns of patients with chronic fatigue, and guides you if evaluation by another department is needed.
Do I need an evaluation even if my blood tests are normal?
Yes. ME/CFS is not diagnosed by blood tests, so a normal result means other causes are less likely, not that you have no symptoms.
Normal results are also useful reference material for comparing your course, so you are welcome to bring them. However, all tests needed for our evaluation are done at our clinic.
Could feeling worse the day after going out also be PEM?
It could. Post-exertional malaise (PEM) may appear not right after activity but some time later. If fatigue, pain, fogginess, and other symptoms worsen together and persist after an outing that used to be no problem, it is worth checking whether it fits PEM.
However, timing and duration differ from person to person, so recording what activity you did, when which symptoms worsened, and how long recovery took helps the judgment at your visit.
Can brain fog and fatigue occur together?
Yes, they often appear together. In an ME/CFS evaluation, difficulty concentrating, remembering, and organizing thoughts (brain fog) is one of the main items checked along with orthostatic symptoms, and it may worsen together when fatigue increases after activity.
However, brain fog can also come from other causes such as lack of sleep, medications, depression or anxiety, or thyroid disease, so an evaluation that rules out causes is needed along with the fatigue.
Do you also check palpitations and dizziness when standing?
Yes. Orthostatic intolerance — dizziness, palpitations, or nausea on standing that improves when lying down or sitting — is one of the main symptoms looked at in an ME/CFS evaluation.
When needed, we measure changes in blood pressure and pulse lying down and after standing to look for coexisting problems such as postural orthostatic tachycardia syndrome (POTS) or orthostatic hypotension, and manage any confirmed problem accordingly.
Can chronic fatigue syndrome be diagnosed with HRV?
No. Heart rate variability (HRV) alone cannot confirm or rule out ME/CFS.
HRV is an indicator for referencing autonomic function and is affected by many factors such as breathing, posture, time of measurement, medications, and sleep. At our clinic, we use it as reference material to look at coexisting autonomic problems and compare your course.
Is all post-COVID fatigue ME/CFS?
No. Fatigue after infections, including COVID-19, can last a long time, and some cases may meet ME/CFS criteria, but not all post-infectious fatigue is ME/CFS.
For post-infectious fatigue as well, we evaluate in the same way whether post-exertional worsening, unrefreshing sleep, cognitive and orthostatic symptoms, and functional decline persist for a certain period, and whether there are other causes.
What records and test results should I prepare before my visit?
Please prepare a list of your medications and supplements, when the symptoms started and your infection history, and a log of recent activities and symptom changes. You may bring test results from elsewhere as reference material, but all tests needed for our evaluation are done at our clinic.
In particular, writing down even a few days of "after which activity, from when, which symptoms got worse, and how long recovery took" helps the evaluation greatly.
What should I check when visiting from another region?
Before your visit, check available appointment times on the booking page, and most importantly, bring your medication list and a log of recent activities and symptom changes.
Even if you have been tested elsewhere, all tests needed for our evaluation are done at our clinic. Previous results are used as reference material for comparing your course.
The scope of evaluation possible on the day and the schedule afterward depend on your symptoms, so if you are coming from far away, let us know when booking and we will advise you. Travel itself can trigger post-exertional worsening, so please plan generous rest time before and after travel.
Preparation for visitors from other regions
To lighten the burden of your first visit, preparing the items below in advance lets us focus the consultation time on evaluating your symptom course.
What to prepare before your visit
- A list of your medications and supplements — names and doses of prescription drugs, over-the-counter drugs, and supplements
- When symptoms began and infection history — when it started, and whether it began after an infection (such as COVID-19)
- A log of recent activities and symptom changes — a few days' record of how symptoms changed after activity
Location and booking
- ClinicYonsei DANA ENT Clinic
- AddressRooms 322–323, Lemeilleur Jongno Town, 19 Jongno, Jongno-gu, Seoul (Jongno 1-ga)
- Phone0507-1384-5075
- TransitWalking distance from Jonggak Stn (Line 1) and Gwanghwamun Stn (Line 5)
- BookingPlease check hours and available appointments on the booking page.
If there is anything we should know in advance (traveling a long distance, coming with a companion, using a wheelchair, etc.), please tell us when booking and we will help as far as possible.
Related pages
Sources used for this page
This page is based on the following official sources. You can check the latest version of each source directly through the links.
- ME/CFS Basics · Symptoms of ME/CFSU.S. Centers for Disease Control and Prevention (CDC) — cdc.gov/me-cfs/about/, cdc.gov/me-cfs/signs-symptoms/
- Diagnosing ME/CFS · Clinical Overview of ME/CFS (for clinicians)U.S. Centers for Disease Control and Prevention (CDC) — cdc.gov/me-cfs/hcp/diagnosis/, cdc.gov/me-cfs/hcp/clinical-overview/
- Myalgic encephalomyelitis (or encephalopathy)/chronic fatigue syndrome: diagnosis and management (NG206)UK National Institute for Health and Care Excellence (NICE), published October 2021 — nice.org.uk/guidance/ng206
- Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness (2015)Institute of Medicine (IOM, now the U.S. National Academy of Medicine) — nationalacademies.org/read/19012