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Family MedicineCondition·Updated Sep 11, 2026·v1

ME/CFS

Myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are overlapping names for a chronic, disabling, multisystem illness; current clinical practice commonly uses the combined term ME/CFS.

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Quick Reference

AvoidDo not use graded exercise therapy or fixed-increment activity programmes, and do not prescribe routine antimicrobials, antivirals, or immunomodulators solely because the patient meets ME/CFS criteria.
DxTest of choiceClinical diagnosis based on substantial functional reduction, delayed post-exertional malaise, unrefreshing sleep, required cognitive or orthostatic features, duration, and assessment for better alternative explanations.
ScKey scoreDuration threshold: NICE at least 3 months; NAM/CDC and CCC at least 6 months in adults, commonly 3 months in children and adolescents.
When to referArrange urgent same-day assessment for chest pain, dyspnoea at rest, hypoxaemia, sustained or exertional syncope, focal neurologic deficit, delirium, rapidly progressive weakness, severe dehydration or bleeding, suicidal intent, or haemodynamic instability.
Recognize ME/CFS from substantial functional decline with delayed, disproportionate, prolonged PEM and unrefreshing sleep, protect the patient’s activity envelope, and investigate symptoms that suggest an independent condition.
ME/CFS is a chronic, disabling multisystem illness defined clinically by substantial functional reduction, delayed and prolonged post-exertional malaise, unrefreshing sleep, and cognitive, autonomic, or broader multisystem symptoms. No validated diagnostic biomarker exists. Primary care should identify the characteristic activity-response pattern, assess severity and safety, investigate targeted alternatives, protect the patient’s activity envelope, treat comorbidities, and provide accessible longitudinal support.

Overview and Recommendations

Background

  • and are overlapping names for a chronic, disabling, multisystem illness commonly called . Do not diagnose it from fatigue alone; the defining pattern includes (PEM), substantial functional reduction, and additional sleep, cognitive, or autonomic symptoms.
  • is delayed, disproportionate worsening after physical, cognitive, emotional, sensory, or orthostatic activity, with recovery that may take days or weeks. Ordinary tiredness that resolves with usual rest does not establish ME/CFS.
  • The core phenotype combines reduced function, unrefreshing sleep, cognitive impairment, and . Patients may also have pain, headache, sensory hypersensitivity, flu-like symptoms, gastrointestinal symptoms, and a fluctuating or relapsing course.
  • No validated biomarker establishes or excludes . Candidate abnormalities in immune, metabolic, autonomic, vascular, exercise, sensory, and neuroimaging studies remain investigational, so diagnosis depends on the clinical pattern and evaluation for better alternative explanations.
  • Apply one case definition transparently. permits diagnosis after at least 3 months when debilitating fatigue worsened by activity, PEM, unrefreshing sleep, cognitive difficulty, functional reduction, and no better explanation are present; NAM/CDC generally uses at least 6 months in adults and 3 months in children and adolescents, while the Canadian Consensus Criteria (CCC) require a broader multisystem phenotype and generally at least 6 months in adults.

Evaluation

  • Establish the change from pre-illness baseline by documenting reliable usual function, not the patient’s best day. Record effects on self-care, domestic tasks, mobility, work or school, communication, social participation, and the assistance or recovery each task requires.
  • Characterize PEM with an event-based history. Ask what activity preceded worsening, whether the trigger was physical, cognitive, emotional, sensory, or upright, when symptoms began, which symptoms changed, how long recovery took, and whether baseline returned.
  • Assess sleep, cognition, and upright tolerance separately. Ask whether sleep restores function; assess attention, processing speed, memory, word finding, and multitasking; and ask whether standing causes dizziness, palpitations, weakness, nausea, visual dimming, presyncope, or syncope that improves when lying down.
  • Record onset and course, including preceding infection, surgery, trauma, pregnancy, medication change, sleep disruption, or other illness, but treat chronology as a clue rather than proof of causation. Infectious mononucleosis, COVID-19, influenza-like illness, and other physiologic stressors may precede illness without proving a persistent infection or a specific cause.
  • Examine without provoking deterioration. Use a quiet, low-stimulation setting, allow pauses, minimize transfers and prolonged upright activity, and interpret a normal brief examination cautiously because it does not measure sustained capacity or delayed post-exertional worsening.
  • Measure orthostatic heart rate and blood pressure only when clinically safe and tolerated, recording posture, duration, symptoms, and reason for stopping. In one ME/CFS cohort, was defined as a heart-rate increase of at least 30 beats/min or an absolute heart rate of at least 120 beats/min during a 10-minute lean test; do not insist on prolonged standing or maximal exercise testing.
  • Investigate plausible alternatives with a targeted initial panel for persistent unexplained fatigue: , ferritin, electrolytes, renal function, liver function, calcium, glucose or , , or , and urinalysis. Add a pregnancy test when pregnancy is possible, and order B12, folate, vitamin D, CK, or infectious serology only when the history or examination supports them.
  • Use ECG, ambulatory monitoring, echocardiography, chest imaging, pulmonary function testing, sleep testing, neurological imaging, or nerve studies only when symptoms, examination, or initial results provide an indication. Investigate chest pain, dyspnea at rest, hypoxemia, sustained syncope, focal neurological deficit, delirium, rapidly progressive weakness, severe dehydration, bleeding, hemodynamic instability, suicidal intent, or unexplained fever urgently.
  • Do not use a positive antibody result, abnormal autonomic test, illness trigger, or proposed biomarker as the diagnosis. Do not use normal routine tests to invalidate functional impairment or a nonspecific abnormality as proof of ME/CFS; reassess unexpected or borderline results and continue evaluation if new focal, abrupt, severe, or progressive symptoms emerge.
  • When duration or criterion coverage is incomplete, document a provisional diagnosis and a reassessment plan rather than forcing certainty. A daily record of activity, PEM latency, symptom change, recovery, sleep, cognition, upright tolerance, and assistance can clarify fluctuating illness without deliberately provoking PEM.

Management

  • Protect the patient’s current activity envelope: the total physical, cognitive, emotional, sensory, social, and upright demand that can be repeated without delayed worsening. Set it from reliable usual function, not a single good day, and review it as symptoms change.
  • Use individualized energy management rather than a quota. Fragment tasks, alternate higher- and lower-demand activities, sit or lie down for tasks when possible, plan rest before predictable exertion, delegate or simplify essential work, and use equipment that reduces upright or sensory demand.
  • During PEM or a crash, stop attempts to maintain the previous schedule. Reduce activity to essential hydration, nutrition, toileting, medicines, communication, and safety; lower sensory and cognitive input; use recumbent or supported positions; and resume other activities only after symptoms stabilize, beginning at the newly tolerated level.
  • Do not prescribe or any generic fixed-increment activity programme. advises against GET and fixed incremental activity or exercise; any physical activity programme offered in selected cases must remain within the person’s energy limit and be delivered by a physiotherapist in an ME/CFS specialist team.
  • If activity is increased after sustained stability, change one demand at a time by the smallest practicable amount and observe the usual delayed-worsening window. If symptoms worsen, return to the last stable level; the endpoint is durable participation within the activity envelope, not normalization of exercise capacity.
  • Start one symptom intervention at a time, use the lowest reasonable dose, and review delayed effects over several days. Stop or reduce treatment that worsens sedation, cognition, orthostatic symptoms, sleep, nausea, or PEM; symptom treatments are not disease-modifying therapies.
  • For sleep, address the sleep phenotype, medication and substance effects, circadian disruption, , and . A cautious trial for circadian delay or sleep initiation is melatonin 0.5-3 mg orally 1-2 hours before the desired bedtime for 2-4 weeks; avoid routine benzodiazepines and sedating antihistamines because of dependence, falls, cognitive effects, and orthostatic hypotension.
  • Treat pain by phenotype and preserve the activity envelope. Options include acetaminophen 500-1000 mg orally every 6-8 hours as needed, not exceeding 3,000 mg/day in routine use, or ibuprofen 200-400 mg orally every 6-8 hours with food for the shortest course when clinically appropriate; avoid NSAIDs with active gastrointestinal bleeding or ulcer disease, significant kidney disease, decompensated heart failure, uncontrolled hypertension, high bleeding risk, or contraindicated pregnancy.
  • For orthostatic intolerance, reduce upright exposure, use slow position changes, cooling, compression, calf activation, and seated or recumbent activity. Increase fluids, often toward 2-3 L/day, and salt only when hypertension, kidney disease, heart failure, hypernatremia, or another contraindication is absent; refer for syncope, marked tachycardia, hypotension, arrhythmia, diagnostic uncertainty, or failure of conservative measures.
  • When persistent orthostatic symptoms warrant medication, specialist or clinician-directed options include fludrocortisone 0.05-0.1 mg orally each morning, titrated to 0.2 mg/day, or midodrine 2.5-5 mg orally three times daily while awake, increased to 10 mg three times daily. Monitor for supine hypertension, potassium abnormalities, edema, urinary retention, and other drug-specific adverse effects.
  • Treat gastrointestinal, allergic, endocrine, inflammatory, sleep, mood, migraine, fibromyalgia, and other coexisting conditions on their own diagnostic evidence. For example, polyethylene glycol 17 g orally daily can be used for constipation, while short-term loperamide can be used for selected diarrhea at 2 mg after the first loose stool and 2 mg after each subsequent stool, up to 8 mg/day, when fever, blood, inflammatory diarrhea, and ileus are absent.
  • Reconcile every prescribed, over-the-counter, supplemental, hormonal, intermittent, and recreational substance at each substantial review. Reduce anticholinergic, sedating, hypotensive, and stimulating burden where possible, and taper drugs that can cause withdrawal rather than stopping them abruptly.
  • Adapt care to severity and access needs. Offer telemedicine, home or collateral assessment, longer appointments, quiet and dim rooms, permission to lie down, scheduled pauses, accessible toilets, written questions, communication aids, and a support person when desired; severe or very severe illness may require home-based care, nutrition support, pressure-care planning, and safeguarding review.
  • Do not prescribe routine antimicrobials, antivirals, immunomodulators, intravenous immunoglobulin, rituximab, metabolic agents, or stimulants solely for an ME/CFS diagnosis. Treat a documented infection or separately established immune-mediated disease according to its own indication, and keep experimental therapy within appropriate research governance.
  • Follow patients longitudinally using sustainable function, PEM frequency and recovery, sleep, orthostatic symptoms, nutrition, medication effects, comorbidities, mood, safety, carer capacity, and work or education demands. Repeat the same measures under comparable conditions, and reassess urgently when new focal, abrupt, severe, progressive, or qualitatively different symptoms appear.

Deep Dive — Evidence Details

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