Fibromyalgia: widespread pain, chronic fatigue and fibro-fog 2026 update

A clinical synthesis based on the ACR 2016 and AAPT 2019 criteria, the EULAR 2017 recommendations, the concept of nociplastic pain (Lancet 2021) and post-COVID data from 2024-2026.

Fibromyalgia has changed profoundly in the scientific literature: long regarded as a poorly defined functional disorder, it is today classified as nociplastic pain by the IASP, that is, pain arising from altered nociception with no identifiable lesion of the somatosensory system.¹ This reconceptualisation has major clinical consequences for assessment and management.

How is this condition defined, who does it affect and what are the risk factors?

Fibromyalgia is defined by four cardinal symptoms: chronic widespread pain, intense fatigue, unrefreshing sleep and cognitive difficulties (the \"fibro-fog\": trouble concentrating, working memory).² The diagnosis has not relied on the count of 18 tender points since 2010; it rests on the revised ACR criteria (Wolfe 2016) or the AAPT 2019 criteria (Arnold).³,⁴

Both global prevalence of fibromyalgia depends closely on the criteria used. The Heidari 2017 meta-analysis (Rheumatol Int) reports a prevalence of around 1,8 % à 2,9 % in the general population with the ACR 1990 criteria, but it rises to 5,4 % with the modified 2010 criteria in the British prevalence study by Jones 2015 (Arthritis Rheumatol).⁵,⁶ This variability reflects the growing sensitivity of the criteria but also a persistent methodological debate.

The female-to-male ratio varies widely with the criteria used: with the ACR 1990 criteria (which required 11 tender points out of 18) it reached 7-9:1, but it falls to 2:1 with the 2010 criteria, which drop tender point palpation.⁷

The risk factors are multifactorial:

• Genetics: heritability is estimated at around 50 %, with strong familial aggregation (RR x8 in first-degree relatives). Polymorphisms of serotonergic (5-HTT, 5-HT2A), dopaminergic (DRD4, COMT) and catecholaminergic genes are implicated (Park & Lee 2017).⁸
• Environmental triggers: physical trauma (whiplash in particular), infections (Lyme disease, EBV, hepatitis C, COVID-19) and intense psychological stress can precipitate the syndrome.⁹
• Comorbidities: fibromyalgia coexists with rheumatoid arthritis in 18-24 %, lupus in 30 %, Sjögren's syndrome in 50 % and axial spondyloarthritis in 14-16 % of cases.⁶
• Sex: sex hormones, differences in nociceptive thresholds and X chromosome-linked gene expression partly explain the female predominance.⁷

What happens in the body and how does fibromyalgia progress naturally?

The core mechanism is central sensitisation, that is, an amplification of nociceptive signalling within the CNS, which shows clinically as:¹,²

1. Hyperalgesia : an exaggerated response to a normally painful stimulus.
2. Allodynia : pain in response to a non-painful stimulus (clothing, vibration).
3. Temporal summation that is increased (\"wind-up\").
4. Deficient descending modulation (impaired conditioned pain modulation testing).

These mechanisms rest on several documented neurobiological changes:

• Low-grade glial neuroinflammation : activation of microglial and astrocytic cells releasing pro-inflammatory cytokines (IL-6, TNF-alpha) and chemokines (Ji 2018 Anesthesiology). This neuroinflammation has been demonstrated on PET imaging with a translocator protein (TSPO) tracer.¹⁰
• Neurotransmitter imbalances : reduced serotonin and noradrenaline (which inhibit pain); raised substance P (threefold in the CSF) and glutamate.²
• Overactive HPA axis and dysautonomia: predominant sympathetic tone, loss of heart rate variability.
• Gut dysbiosis : recent 2023-2025 Mendelian randomisation studies suggest a causal link between microbiota changes and symptom severity.¹¹

The natural course is chronic and fluctuating. The prospective Walitt 2011 study of 1555 patients followed for 11 years in the NDB cohort showed that symptom severity remains broadly stable, with only 25 % achieving meaningful improvement and fewer than 10 % complete remission.¹² Poor prognostic factors include: severe symptoms at diagnosis, psychiatric comorbidity, low physical activity, catastrophising and low self-efficacy.¹³

Which questions should you ask to understand the patient and their history?

History taking is the cornerstone of the diagnosis. It should explore five key dimensions:¹,²

• Pain description and distribution : mapping, on a body chart, the 19 areas of the Widespread Pain Index (WPI) (shoulder L/R, hip L/R, thigh L/R, lower leg L/R, jaw L/R, upper arm L/R, forearm L/R, chest, upper back, lower back, neck, abdomen). Key question: \"Over the past week, in how many areas have you had pain?\"³
• Severity of associated symptoms : rating fatigue, unrefreshing sleep and cognitive symptoms from 0 to 3 (Symptom Severity Scale - SSS). Added to this is the presence or absence over the past 6 months of headache, lower abdominal pain and depression (possible total 0-12).³
• Timeline and triggers : symptom duration (the criterion requires ≥ 3 months at a similar level), potential trigger (infection, trauma, surgery, stress), fluctuating course.
• Functional impact : effect on work, social life, sleep and daily activities. The Fibromyalgia Impact Questionnaire Revised (FIQR) is the reference tool (0-100, MCID ≈ 14 points).⁴
• Treatment history : drug and non-drug treatments already tried, perceived response, adverse effects.

The question of the patient's beliefs and representations about their pain is crucial: kinesiophobia, catastrophising and an external locus of control predict a poorer response to active interventions.⁵

Which clinical tests should you carry out and which other conditions must be ruled out?

The positive diagnosis rests on the ACR 2016 criteria (Wolfe), which combine two scores:³

The AAPT 2019 criteria (Arnold) are a simpler alternative validated by the IASP-American Pain Society:⁴

1. Widespread pain affecting ≥ 6 sites out of 9 (head, arm L/R, chest, abdomen, upper back, lower back, leg L/R).
2. Unrefreshing sleep OR fatigue (at least moderate).
3. Symptoms present for ≥ 3 months.

Physical examination remains useful for excluding organic disease. Look for: inflammatory joint signs (swelling, redness), neurological deficits (power, sensation, reflexes), cardiac murmurs, lymphadenopathy and thyroid signs. Palpation may reveal widespread hyperalgesia (a sign of central sensitisation) but is no longer required for the diagnosis.³

The minimum laboratory work-up recommended by EULAR for the differential diagnosis includes:⁸

• FBC, ESR, CRP (to exclude systemic inflammation)
• TSH (to exclude hypothyroidism)
• CPK (creatine phosphokinase; excludes myopathy)
• Vitamin D (deficiency is common and may worsen muscular symptoms)
• Ferritin (iron deficiency is common in women)
• Serum calcium, fasting blood glucose

Routine imaging has no place in the positive diagnosis of fibromyalgia. It is reserved for red flags or a specific clinical target.⁷

Main differential diagnoses:

• Rheumatoid arthritis : symmetrical arthritis, rheumatoid factor/anti-CCP, raised ESR/CRP.
• Systemic lupus : SLICC criteria, ANA, anti-DNA, skin and kidney involvement.
• Sjögren's syndrome : sicca syndrome, anti-SSA/SSB, salivary gland biopsy.
• Hypothyroidism : raised TSH, low T4, endocrine signs.
• Polymyalgia rheumatica : age > 50, girdle pain, ESR > 50.
• Axial spondyloarthritis : inflammatory back pain, HLA-B27, sacroiliac MRI.
• Chronic fatigue syndrome / ME-CFS : prolonged post-exertional malaise.
• Vitamin D deficiency and iron deficiency.
• Adverse drug effects (statins, aromatase inhibitors).

How do you sort patients into clinically useful subgroups?

The great heterogeneity of patients with fibromyalgia partly explains why meta-analyses show only moderate clinical effects: an \"overloaded\" patient with extreme catastrophising will not respond like an \"adaptive\" patient with low distress. The effort of phenotyping or profiling aims to personalise interventions.¹

Several cluster analysis studies (Vincent 2014, de Souza 2009, Yim 2017) converge on 3 to 4 recurring subgroups :²,³

The Migliorini 2025 study (Med Sci, level I) in juvenile fibromyalgia suggests a similar stratification in paediatrics, with cognitive behavioural approaches being particularly effective in adolescents with high distress.⁴

The Brazilian SR 2025 review (parts I & II) confirms the clinical usefulness of phenotyping and proposes a decision algorithm based on the FIQR score and the clinical subtype.⁵,⁶

What is the place of medication in fibromyalgia?

The EULAR 2017 recommendations are clear: no drug is a first-line treatment. Medication has the role of an adjunct , making it easier to engage in active therapies (exercise, CBT) when pain, sleep or mood are too badly affected.⁷

Three drugs are approved by the FDA for fibromyalgia in the United States (but not in France or Europe): duloxetine, milnacipran and pregabalin.⁸ None is approved specifically for this indication in Europe.

Prescribing principles:

• Start low, go slow (\"start low, go slow\") because patients with fibromyalgia are sensitive to adverse effects.
• Reassess at 8-12 weeks : if there is no notable benefit, stop rather than stacking drugs.
• Avoid strong opioids entirely (morphine, oxycodone): no demonstrated benefit, risk of dependence and opioid-induced hyperalgesia.⁷,⁸
• Tramadol : a weak option if other treatments have failed, but there is a risk of serotonin syndrome with SNRIs.
• NSAIDs and paracetamol : of little use as monotherapy for fibromyalgia pain (nociplastic, not inflammatory).
• Corticosteroids : no place at all.
• Cannabinoids : emerging evidence (Sarzi-Puttini 2020), notably nabilone for sleep; they remain tightly regulated in France.

The stepped care approach offers a rational escalation:⁹

1. Step 1: Education + exercise + self-management (8-12 weeks)
2. Step 2: If this fails, add CBT + consider low-dose amitriptyline (10-25 mg at night)
3. Step 3: If failure persists and FIQR > 60, consider duloxetine, milnacipran or pregabalin (12-week trial)
4. Step 4: Intensive interdisciplinary management in a pain centre

Where do you start? What is the recommended hierarchy of interventions?

The EULAR 2017 recommendations marked a turning point by placing physical exercise as the only intervention with a strong recommendation for every patient with fibromyalgia.¹ The other interventions are rated \"weak for\" or \"weak against\" depending on the benefit-risk-cost balance.

The most effective approach is multimodal. The Hauser 2009 meta-analysis (Arthritis Care Res) of 9 RCTs showed that combining exercise + education + CBT is superior to any single component, with effects lasting a year for pain, fatigue and mood.²

Practical hierarchy:

1. Foundation: therapeutic patient education (ETP); explaining the nociplastic mechanisms; therapeutic alliance.
2. Central pillar: an individualised, graded exercise programme built on the patient's preferences.
3. Psychological support: CBT, ACT, MBSR according to profile and acceptability.
4. Adjuncts: hydrotherapy, drug neuromodulation if these fail, occasional passive therapies during a flare.

What is the place of exercise, and is any one approach superior?

Exercise is the intervention validated with the highest level of evidence. Successive Cochrane meta-analyses confirm significant effects on pain (SMD ~ -0.5), function (SMD ~ -0.6) and quality of life.³,⁴

There is no clear evidence that one type of exercise is superior to another; the choice should follow patient preference to secure adherence:⁵

The key principle is \"Start Low, Go Slow\" : start well below the patient's perceived limits and increase one parameter at a time (frequency, duration, intensity).⁶ A pragmatic rule: if pain rises by more than 2 points on the VAS for 48h after a session, reduce the load by 25 %.

A typical beginner programme (adapted from Bidonde 2017 / Busch 2013):

• Phase 1 (weeks 1-4): 20 min gentle walking 3x/week + 15 min general mobility + breathing. No more than 50 % of maximum heart rate.
• Phase 2 (weeks 5-8): add low-load segmental strengthening (50 % 1RM, 8-12 reps, 2 sets, 2x/week).
• Phase 3 (weeks 9-12): gradually build up walking or cycling (to 30-40 min) + progressive strengthening.
• Phase 4 (3+ months): find an enjoyable activity for independent maintenance.

Manual therapies and technologies: how effective are they really?

Passive therapies have a limited place; they are often requested by patients hoping for an external solution, but the evidence of lasting benefit is weak.⁷

• Therapeutic massage : a short-term effect on pain and anxiety (Yuan 2015 meta-analysis, moderate NNT), but the effect is not maintained beyond 6 weeks. Useful as an adjunct to open the way into exercise.⁸
• Mobilisations / manipulations : very weak evidence. Not recommended as core practice, but they may ease associated cervicothoracic tension points.
• Balneotherapy / warm hydrotherapy : short-term benefit on pain and quality of life (Nuesch 2013 Ann Rheum Dis NMA), probably multifactorial (heat, buoyancy, gentle exercise, relaxation).⁹
• TENS, ultrasound, laser, shockwave : limited and heterogeneous evidence. The Salazar 2017 review concludes that there is insufficient evidence to recommend electrical stimulation in routine practice.¹⁰
• Acupuncture : moderate short-term effects (Deare 2013 Cochrane). Less effective than exercise, but it may be a preferred option for some patients.
• rTMS (repetitive transcranial magnetic stimulation) : emerging evidence, mainly over the motor cortex. It remains experimental in clinical practice.

These modalities should be regarded as temporary adjuncts that modulate symptoms in order to make engagement in active strategies easier.¹,⁷

Beyond the physical: how do you educate the patient and address psychological factors?

The pain neurophysiology education (PNE) has become a standard. It aims to deconstruct mistaken beliefs (\"my muscles are damaged\", \"the more it hurts the more serious it is\") and to reconceptualise pain as an experience modulated by the brain rather than a pure signal of tissue damage.¹² The Suso-Marti 2022 meta-analysis (Pain Med) of 8 RCTs shows significant moderate effects on pain (SMD -0.5) and impact (SMD -0.7), with low-quality evidence.¹³

Both Cognitive Behavioural Therapy (CBT) is the most studied psychological approach. The Bernardy 2018 meta-analysis (Eur J Pain, 23 RCTs, 2031 patients) confirms significant but moderate effects on:¹⁴

• Pain (SMD -0.32; 95 % CI -0.49 to -0.15)
• Depressive mood (SMD -0.33)
• Functional capacity (SMD -0.32)
• No significant effect on fatigue or on sleep alone

Both acceptance and commitment therapy (ACT) and mindfulness-based stress reduction (MBSR) are effective alternatives (Veehof 2016) with results comparable to standard CBT, and are sometimes better accepted by patients who resist a \"cognitive\" approach.¹⁵

The caveats to bear in mind: even statistically significant effects are moderate in practice (Δ ~ 1-1.5 points/10 VAS), and sometimes below the minimal clinically important difference (MCID). The individual response is highly heterogeneous; some patients are \"super-responders\", others gain no benefit at all. This strengthens the case for phenotyping.⁴,¹⁵

How do you make the patient an active player in their recovery through self-management?

Patient self-care (self-management) is the component that secures long-term benefit. It brings together 4 pillars:¹

• Structured therapeutic education : 4 to 8 sessions covering the pathophysiology, the triggers and coping strategies. Individual or group format; the group format has shown added benefit through social support (Brazilian SR 2025).²
• Pacing (activity regulation) : balancing activity and rest to avoid the \"boom-bust\" cycle (overactivity followed by exhaustion and a pain flare). A practical tool: the \"50 %\" rule - on a good day, do not go beyond 50 % of perceived capacity, so as to keep something in reserve for harder days.
• Sleep hygiene : regular hours, limiting screens for 1h before bed, avoiding caffeine after 2 pm, the 4-7-8 breathing technique. Amitriptyline 10-25 mg for insomnia can make this phase easier.
• Stress management : relaxation techniques, mindfulness meditation, a stress diary identifying personal triggers.

The self-efficacy (the perception of one's own ability to control the illness) is a key mediator of outcomes. The Theadom 2019 meta-analysis (PLOS One) on self-management shows significant effects at 12 months on self-efficacy (SMD +0.38) and pain intensity (SMD -0.32), even though the effect on fatigue remains limited.³

When and how do you plan a safe return to sport and activity?

The return to physical and social activity must be planned methodically to avoid setbacks. The principles:⁴

1. Choose an enjoyable activity : walking, gentle cycling, swimming, tai chi, dance, gentle yoga. The aim is lasting adherence, not physiological optimisation.
2. Mathematical progression : increase only one parameter at a time (frequency OR duration OR intensity). The 10 % rule: do not increase by more than 10 % per week.
3. Activity diary : record the activity, its duration, the perceived intensity and the pain on the day and the day after. This helps identify thresholds.
4. Managing flares : do not stop altogether; reduce temporarily by 25-50 % and resume the progression after 3-5 days.
5. Progression criterion : do not move up a level until the patient tolerates the current one with no worsening 48h later.

Beyond physical activity, the social and occupational return matters just as much:

• Phased return to work : consider a temporary mi-temps thérapeutique (the French phased return to part-time work on medical grounds); ergonomic adjustments (regular breaks, alternating sitting and standing, suitable lighting).
• Support networks : patient associations (in France: FibromyalgieSOS, Association Francaise de la Fibromyalgie); avoid the social isolation that worsens catastrophising and depression.
• Engaging in meaningful activities : even modest ones strengthen the sense of efficacy and soften the \"chronically ill\" self-image.

Progress indicators to track (in addition to the FIQR):

• Daily step count (a graded target: +500/week up to 6,000-8,000)
• PSQI score (sleep quality)
• PCS score (catastrophising) - should fall
• Self-efficacy (Lorig scale)
• Movement tolerance (movement-hold)
• Return to meaningful activities (social, family, work)

Analysis of a \"classic\" case: from assessment to resolution.

This case illustrates an effective multimodal care pathway. A 45-year-old woman, diagnosed 10 years earlier, initial assessment:

• Pain : 7/10 VAS, widespread distribution (shoulders, back, hips, legs)
• Associated symptoms : disabling fatigue (7/10), unrefreshing sleep, fibro-fog affecting work
• Initial FIQR : 72/100 (severe impact)
• PCS : 38 (severe catastrophising)
• ACR 2016 criteria : WPI 12, SSS 10 → diagnosis confirmed
• Laboratory work-up : normal (FBC, ESR, CRP, TSH, CPK, ferritin)

Interdisciplinary management over 12 weeks:

1. Therapeutic education (4 sessions of 90 min) covering: nociplastic pathophysiology, deconstructing mistaken beliefs, the principles of pacing, sleep hygiene.
2. Individualised exercise programme : graded walking (from 10 to 30 min, 3x/week) + low-load segmental strengthening (20 % 1RM rising to 50 %) + 1 weekly session of warm-water hydrotherapy.
3. Group CBT (12 weekly sessions) targeting catastrophising, kinesiophobia, cognitive restructuring and stress management techniques.
4. Drug adjunct : amitriptyline 10 mg at night for insomnia (first 3 weeks), then tapered off.

Results at 12 weeks:

The patient kept up her programme at 6 months (with no supervised sessions) and the gains held steady. This case shows that even after 10 years of symptoms, a structured approach can transform the trajectory.

The diagnostic challenge: when fibromyalgia mimics another condition.

The differential diagnosis is crucial, because FM symptoms overlap with those of many conditions. Two situations deserve particular attention:

Case 1: Post-COVID fibromyalgia. A case series reported by Ursini 2021 (RMD Open) describes patients (n=189, mean age 47, 88 % women) who developed a full picture of FM 3 to 12 months after a moderate COVID-19 infection, with no previous history of pain.¹ The ACR 2016 diagnostic criteria were met in 30 % of participants. The British cohort study (Long COVID Plus, 2024) confirms an HR of 1.7 for a diagnosis of FM within the 16 months following infection. These cases blur the boundary between long COVID and fibromyalgia and suggest shared pathophysiological mechanisms (neuroinflammation, dysautonomia).

Case 2: Overlap with hypermobile Ehlers-Danlos syndrome (hEDS). Several cohort studies (notably Tinkle 2020) report frequent comorbidity: up to 40-80 % of patients with hEDS also meet the FM criteria. The typical presentation: widespread pain and fatigue, but with generalised hypermobility (Beighton score ≥ 5/9), hyperextensible skin and a family history. The risk is of making an isolated diagnosis of FM and missing the hEDS, which changes management (specific strengthening for joint stability, prevention of subluxations). The current nomenclature and the dosing of exercise in this setting are covered in joint hypermobility syndromes.

A complex case study and syndromic overlaps.

Fibromyalgia is rarely isolated. A Vincent 2013 study of 502 patients at the Mayo Clinic shows that 89 % have at least one other chronic condition, most often:²

• Irritable bowel syndrome (IBS): 30-70 %
• Migraine / tension-type headache: 35-55 %
• Major depressive disorder: 30-40 %
• Generalised anxiety disorder: 25-35 %
• Temporomandibular disorders (TMD): 20-35 %
• Chronic fatigue syndrome (ME-CFS): 20-50 %
• Interstitial cystitis: 5-15 %
• Vulvodynia: 5-15 %

A multidisciplinary approach is essential here. Illustrative case : a 38-year-old woman with severe FM (FIQR 80), associated IBS, a history of early psychological trauma (ACE score 6/10) and untreated PTSD. A purely physical approach (physiotherapy alone) is doomed to fail here; working with a psychiatrist or psychotherapist (EMDR or trauma-focused therapy) is essential to unlock the trajectory.³ After 18 months of integrated care, the FIQR fell to 45, the IBS stabilised and function was partly restored.

Other case studies explore the potential role of fascial dysfunction in some patients (Liptan 2010, Stecco 2018): associated local myofascial pain, palpable restrictions in fascial mobility. Although the level of evidence remains low, targeted fascial manual therapy may be useful in patients with a marked peripheral component, alongside the central approach.⁴ The distinction between the two pictures, and what trigger point palpation is really worth, are set out in the article on myofascial pain syndrome.

Critique and controversy

The persistent absence of a diagnostic biomarker feeds medical scepticism. This lack of visible objective proof still explains the stigma patients face and the average 5 years of diagnostic wandering before the diagnosis is made. Advances in functional imaging (TSPO PET, fMRI), plasma metabolomics and molecular biology nevertheless converge: FM is a measurable pathophysiological reality, simply not one that a routine blood test can yet capture.⁵,⁶

The great heterogeneity of phenotypes fuels the debate: is FM a single disease or a \"nociplastic spectrum\" encompassing several subtypes? The current consensus (Fitzcharles 2021 Lancet) argues for a spectrum, which justifies the effort of phenotyping and the individualisation of treatment.

When, and to which other health professionals, should you refer?

Interprofessional referral is a fundamental clinical skill. It rests on two kinds of signal: red flags (organic disease) and yellow flags (psychosocial factors).¹

The red flags (Finucane 2020) call for an urgent or specialist medical opinion:²

The yellow flags of a psychosocial kind (Nicholas 2011) justify working with a psychologist or psychotherapist:³

• Severe catastrophising (PCS > 30)
• Moderate to severe depression (PHQ-9 > 15)
• Severe anxiety (GAD-7 > 15)
• High kinesiophobia (Tampa Scale for Kinesiophobia > 40)
• Untreated history of trauma (high ACE score)
• Suicidal thoughts (screen systematically - rates 2-3x higher in FM)
• Marked social isolation

A useful interprofessional network:

How do you measure outcomes and overcome barriers to implementation?

Standardised outcome measurement is essential for steering treatment and demonstrating effectiveness. The PROMs recommended for fibromyalgia:

Recommended frequency: initial assessment + reassessment at 4, 8 and 12 weeks then at 6 and 12 months in follow-up.

Barriers to implementation (da Silva 2015):⁴

• Lack of time : adopt a quick workflow (questionnaires in the waiting room, automatic scoring)
• Lack of skills : continuing education (FIF-PL and DPC, the French funding and continuing professional development schemes for physiotherapists)
• Lack of resources : use free platforms (rheumcalc.com for the FIQR, online scoring)
• Organisational inertia : start small (one PROM per patient, then extend gradually)
• Patient resistance : explain how the scores help personalise follow-up

Effective strategies : audit and feedback, interactive training, integration into the electronic patient record, mentoring by clinical champions.⁵