Fibromyalgia

Fibromyalgia is a chronic centralized pain syndrome producing widespread musculoskeletal pain, diffuse tenderness, unrefreshing sleep, fatigue, and cognitive dysfunction ("fibro fog") that is not attributable to a separate structural, inflammatory, or metabolic disease. It reflects a genuine disorder of central pain processing — central sensitization, in which the nervous system itself amplifies and prolongs normal sensory input — rather than ongoing tissue damage or inflammation in the painful areas themselves, which is why acetaminophen, NSAIDs, and inflammatory-marker testing typically contribute little to either diagnosis or symptom relief.^[1]

Fibromyalgia most often begins in mid-adulthood, predominantly affects women, and frequently coexists with irritable bowel syndrome, irritable bladder syndrome, migraine, and mood or anxiety disorders — a shared vulnerability to central sensitization rather than coincidence. Because its diagnosis depends on pattern recognition rather than a confirmatory test, both under-recognition and misattribution are common; the single most important framing point for pharmacist counselling is that this is a real, biologically grounded condition deserving the same clinical seriousness as any other chronic disease. Management is built on a nonpharmacologic foundation — structured education, graded exercise, and cognitive behavioural therapy — with pharmacotherapy positioned only as a modest adjunct, never a cure.^[2]

Typical presentation

Patients describe diffuse, aching, or burning pain affecting both sides of the body and both above and below the waist, often including the axial skeleton (neck, back, chest). Pain intensity commonly fluctuates day to day and is frequently aggravated by physical or emotional stress, poor sleep, weather change, or overexertion. Alongside the pain itself, three features are almost universally present and are as clinically important as the pain: unrefreshing, nonrestorative sleep (waking feeling as tired as at bedtime); pervasive fatigue disproportionate to activity level; and cognitive dysfunction — difficulty concentrating, word-finding difficulty, and short-term memory lapses, often called "fibro fog." Diffuse tenderness to palpation is typically present but is no longer required for diagnosis (see Assessment & Diagnosis).

Commonly co-occurring conditions

Fibromyalgia shares an underlying vulnerability to central sensitization with several other conditions, which commonly occur in the same patient rather than as a separate coincidental diagnosis:^[3]

• Somatic pain conditions — irritable bowel syndrome, chronic pelvic pain, migraine, and other chronic headache.
• Psychiatric conditions — major depressive disorder, anxiety disorders, post-traumatic stress disorder, and substance use disorder.
• Sleep disorders — obstructive sleep apnea, restless legs syndrome.
• Other rheumatic conditions — rheumatoid arthritis, systemic lupus erythematosus, and other connective tissue diseases (fibromyalgia can coexist with, and complicate the assessment of, an established rheumatic diagnosis).
• Other associations — joint hypermobility syndrome, rhinitis and urticaria, irritable bladder syndrome, cold intolerance, and paresthesias.

Historical note on the tender-point examination

The original 1990 American College of Rheumatology classification relied on a formal tender-point examination (pain on digital palpation at 11 of 18 specified sites). Current diagnostic criteria (the 2016 ACR revision and the 2019 AAPT criteria, both in Assessment & Diagnosis) no longer require a tender-point count — general widespread tenderness on examination supports the diagnosis, but a normal or incomplete tender-point count does not exclude it.

• Female sex — fibromyalgia is diagnosed far more often in women than men, though true male prevalence may be underestimated by criteria historically validated mainly in women.
• Age of onset typically between 30 and 60 years, though fibromyalgia can occur at any age, including rarely in adolescents.
• A personal or family history of chronic pain, including a family history of fibromyalgia itself — genetic and shared-environment factors both appear to contribute.
• A history of physical, sexual, or emotional trauma or other significant adverse life events, including post-traumatic stress disorder.
• A comorbid mood or anxiety disorder.
• An existing chronic pain condition or rheumatic disease (e.g., rheumatoid arthritis, systemic lupus erythematosus) — fibromyalgia occurs more often in patients with an established inflammatory or autoimmune diagnosis than in the general population.
• Certain infections (e.g., Epstein-Barr virus, Lyme disease) have been proposed as potential triggers preceding symptom onset in some patients.
• Obesity and physical deconditioning.
• A comorbid sleep disorder, including obstructive sleep apnea and restless legs syndrome.

Differentiating fibromyalgia from other causes of chronic widespread pain

Fibromyalgia frequently coexists with the conditions below rather than being a true alternative diagnosis — the purpose of this table is to flag specific features that warrant additional workup, not to exclude fibromyalgia outright.^[4]

History

• Characterize the pain: location, onset, duration, frequency, and aggravating/relieving factors.
• Ask specifically about the accompanying core features — unrefreshing sleep, fatigue, and cognitive dysfunction — since these are as central to the diagnosis as the pain itself.
• Take a personal and family medical history, including prior chronic pain syndromes, mental health history, and current medication/substance use.
• Screen for the red-flag features above and for any of the differential-diagnosis clues in the table.

Examination

• A joint examination, looking specifically for synovitis/swelling and not just tenderness.
• A focused neurological examination.
• An assessment of diffuse tenderness — a general impression of widespread tenderness supports the diagnosis; a formal 18-point tender-point count is no longer required (see Recognize the Condition).

Investigations

Basic laboratory testing is reasonable in most patients presenting with chronic widespread pain, both to support the diagnosis and to screen for the differential-diagnosis categories above: CBC, ESR or CRP, TSH, and creatine kinase are a reasonable baseline panel. Extensive rheumatologic serology (ANA, rheumatoid factor, anti-CCP, HLA-B27) and imaging are not routinely indicated in a patient with a classic history and examination and none of the red-flag or differential-diagnosis features above — order these selectively, guided by the specific findings in the table, rather than as a routine fibromyalgia work-up.

Diagnostic criteria

Two current criteria sets have comparable sensitivity and specificity and either may be used to confirm the diagnosis; neither requires a formal tender-point examination.^[5][3]

2016 revised ACR criteria

A patient meets criteria for fibromyalgia when all of the following are present:

• Generalized pain, defined as pain in at least 4 of 5 body regions (left upper, right upper, left lower, right lower, and axial), has been present for at least 3 months at a similar level.
• The Widespread Pain Index (WPI, 0-19) and Symptom Severity Scale (SSS, 0-12) meet one of two threshold combinations: WPI of 7 or more with SSS of 5 or more, OR WPI of 4 to 6 with SSS of 9 or more.
• The diagnosis is valid regardless of other concurrent diagnoses, and does not exclude the presence of other clinically important illness.

Because the SSS somatic-symptom count draws on a long, nonspecific symptom list and the diagnostic rule itself uses two different qualifying WPI/SSS combinations rather than a single unambiguous point-sum threshold, this platform presents the criteria above as a teaching reference rather than a live interactive calculator — apply the thresholds directly using the tables above.

2019 AAPT criteria (alternative, entirely symptom-based)

A patient meets AAPT criteria when all of the following core features are present for at least 3 months:

• Multisite pain, defined as pain in at least 6 of 9 possible body sites (head, left arm, right arm, chest, abdomen, upper back and spine, lower back and spine including buttocks, left leg, right leg).
• Moderate-to-severe sleep problems, or fatigue, or both.

Supporting features that increase diagnostic confidence but are not required include tenderness, dyscognition, musculoskeletal stiffness, and environmental sensitivity or hypervigilance (e.g., intolerance to bright light, loud noise, or cold).

• Reduce pain intensity from moderate-or-severe toward mild — complete pain resolution is uncommon and should not be the stated treatment goal.
• Reduce fatigue and improve sleep quality, since these core symptoms drive as much disability as the pain itself.
• Improve mood and reduce psychological distress, addressing any comorbid depression or anxiety on its own terms.
• Improve physical function, activity tolerance, and participation in work/social roles — track function alongside pain, not pain in isolation.
• Identify and manage any comorbid condition (irritable bowel syndrome, migraine, sleep apnea, an established rheumatic disease, and others) on an individualized basis.
• Build durable self-management skills through education, rather than creating dependence on any single ongoing treatment.

Validating the diagnosis

Start every management conversation by acknowledging the patient's symptoms as real, and explain the biological basis of fibromyalgia in plain language: central sensitization means the nervous system itself has become an amplifier of pain signals, not that there is nothing physically wrong. Patients who have been told, explicitly or implicitly, that their pain is "not real" or "all in their head" often arrive distrustful and are less likely to engage with a nonpharmacologic-first plan — reframing the pain as a genuine, biologically grounded central-processing problem, while acknowledging that psychological and social factors can influence its expression without being its cause, is itself a therapeutic intervention.^[16]

Structured patient education

Refer to or deliver a structured self-management education program (for example, an arthritis-society self-management course) — combined education and self-management programs improve pain, sleep, fatigue, and quality of life, with benefit that can persist for months. A patient-centred approach that discusses the individual patient's specific psychosocial risk factors for chronic pain, ideally supported by an individualized visual or written explanatory tool, improves the patient's understanding and recall of the management plan.

Exercise — the single highest-yield intervention

Supervised, graded exercise has the strongest evidence base of any individual fibromyalgia intervention.^[1][6]

• Start at a low intensity and duration and progress gradually (graded exercise) — many patients are deconditioned and initially exercise-intolerant, and a pain flare from starting too aggressively undermines adherence.
• Aerobic exercise (walking programs, aquatic exercise, cycling) has the most consistent evidence for improving pain, function, and well-being.
• Resistance/strength training and flexibility training are reasonable additions or alternatives.
• Tai chi has trial evidence comparable to aerobic exercise for symptom improvement and may be better tolerated by some patients.
• Consistency and long-term adherence to whichever modality the patient will actually sustain matters more than the specific type of exercise chosen.

Sleep hygiene

Because unrefreshing sleep is a core diagnostic feature that worsens pain, fatigue, and cognition, address it directly and early: a consistent sleep-wake schedule, a wind-down routine, limiting daytime napping and evening caffeine/alcohol, and screening for a comorbid sleep disorder (obstructive sleep apnea, restless legs syndrome) when sleep problems are severe or refractory.

Cognitive behavioural therapy and psychological support

CBT improves pain coping, mood, and physical function, and is a core rather than optional part of a comprehensive program.^[7] Where a specific identifiable psychological contributor is present — a history of physical, sexual, or emotional trauma, or post-traumatic stress disorder — targeted therapy for that specific issue is a reasonable part of the overall plan.

Other adjunctive nonpharmacologic measures

Heat, cold, transcutaneous electrical nerve stimulation, massage, and relaxation techniques (biofeedback, meditation, hypnosis) are reasonable adjuncts; electroacupuncture appears to outperform manual acupuncture where either is available. A comprehensive multidisciplinary program combining education, exercise, sleep management, and CBT is the model most consistent with current evidence, though it is worth noting honestly that the overall quality and quantity of randomized trial evidence specifically testing combined multidisciplinary programs, as opposed to their individual components, remains limited.^[7]

Ongoing follow-up as a therapeutic tool

Schedule regular follow-up even when no new intervention is planned — ongoing contact and support are themselves valued by patients with fibromyalgia and allow early identification of both inadequate response and comorbidity that needs its own treatment.

Pregnancy

Favor nonpharmacologic measures throughout pregnancy; many fibromyalgia symptoms (widespread pain, fatigue, back pain, stiffness) overlap with normal pregnancy symptoms, and reassurance that this overlap is expected can reduce distress. Most patients report worsening symptoms during pregnancy, especially in the third trimester, and postpartum, though fibromyalgia itself does not appear to worsen pregnancy or newborn outcomes.

Preferred if a drug is genuinely needed acetaminophen for analgesia, and low-dose amitriptyline if an antidepressant-class agent is needed — TCAs have the most reassuring pregnancy data among the fibromyalgia drug classes.

Alternative duloxetine is not associated with an increased major-malformation risk, but has been associated with transient neonatal agitation, jitteriness, and poor feeding when used close to delivery.

Avoid gabapentin and pregabalin — pregnancy safety data remain insufficient to support routine use.

Avoid NSAIDs from approximately 20 weeks of pregnancy onward Health Canada has confirmed a risk of fetal renal impairment and low amniotic fluid (oligohydramnios) with NSAID use from about 20 weeks; NSAIDs are contraindicated in the third trimester (beyond 28 weeks) for this reason, independent of their limited fibromyalgia-specific benefit.^[17]

Avoid tramadol neonatal withdrawal has been reported after prolonged use in pregnancy; reserve for situations where the benefit clearly outweighs this risk, with specialist input.

Breastfeeding

Acetaminophen and ibuprofen are considered compatible with breastfeeding. Amitriptyline is not expected to cause adverse effects in the breastfed infant. Duloxetine's effect on the breastfed infant is not well characterized — weigh the benefit against this uncertainty. Pregabalin transfers into breast milk with limited safety data; some specialists support continuing it with infant monitoring (drowsiness, feeding, weight gain) when no adequate alternative exists. Small amounts of tramadol transfer into breast milk; monitor the infant for sedation and poor feeding if it is used.

Pediatric

Fibromyalgia is uncommon in children and adolescents and is generally managed by pediatric rheumatology using the same nonpharmacologic-first principles (education, graded exercise, sleep hygiene, CBT) that anchor adult management; pharmacotherapy has not been well studied in this age group and should not be extrapolated from adult dosing without specialist input. Do not use tramadol in a child under 12 years of age.

Older adults

Patients with fibromyalgia are often unusually sensitive to medication side effects — start every agent at the lowest available dose and titrate more slowly than in a younger adult. Avoid amitriptyline in patients over 65, or with cardiac disease, glaucoma, or urinary retention risk; nortriptyline (see Neuropathic Pain chapter) is a better-tolerated TCA alternative if a TCA is still the right choice. Reduce the tramadol dose (maximum 300 mg/day) and gabapentinoid dose in this population.

Renal and hepatic impairment

Pregabalin and gabapentin both require dose reduction based on creatinine clearance. Duloxetine should not be used if creatinine clearance is under 30 mL/min or with significant hepatic impairment. Tramadol requires dose reduction if creatinine clearance is under 30 mL/min. Amitriptyline and cyclobenzaprine may need dose reduction and slower titration in hepatic impairment given hepatic metabolism.

Arrange follow-up around 4-6 weeks after starting or adjusting a nonpharmacologic program or a new medication — fibromyalgia symptoms improve gradually, and both exercise programs and pharmacotherapy need a genuine trial period before being judged effective or ineffective.

• Track pain intensity with a simple 0-10 numeric rating scale at every visit, comparing to the pretreatment baseline.
• Track function (activity level, work/social participation), sleep quality, fatigue, and mood at every visit — pain relief without functional improvement is an incomplete response.
• Reassess adherence to the nonpharmacologic foundation (exercise, sleep hygiene, CBT) at every visit, not only medication adherence.
• Screen for evolving or undertreated depression and anxiety at follow-up, given the high comorbidity burden.
• For any drug started, confirm the dose actually reached the usual effective target (see Drug Tables) before judging a lack of response.
• Periodically reassess whether an ongoing medication is still providing meaningful benefit — the initial improvement from pharmacotherapy commonly fades with time, and a planned trial of dose reduction or discontinuation is reasonable once symptoms have been stable, rather than continuing a drug indefinitely by default.
• Document both pain reduction and functional improvement explicitly — function is easy to overlook if only a pain score is tracked.

1. Confirm the nonpharmacologic foundation is genuinely in place — education, a graded exercise program, and sleep hygiene measures — before adding or switching medication; drug therapy added onto an absent nonpharmacologic foundation is unlikely to succeed.
2. Confirm any drug trial was actually adequate: the correct target dose was reached (or the maximum tolerated dose, if lower) for a reasonable trial period, with real adherence.
3. Re-confirm the diagnosis — re-screen against the 2016 ACR or 2019 AAPT criteria, and reconsider the differential-diagnosis table in Assessment & Diagnosis for a feature that was missed.
4. Ensure comorbid conditions (depression, anxiety, irritable bowel syndrome, a sleep disorder, an established rheumatic disease) are being actively treated on their own terms — an undertreated comorbidity is a common driver of apparent fibromyalgia treatment failure.
5. For inadequate response to one 1st-line agent, switch to a different 1st-line class (duloxetine, pregabalin, or low-dose amitriptyline) rather than repeating the same class, or consider a rational combination such as morning fluoxetine plus evening amitriptyline.
6. For a focal, reproducible pain generator (a specific myofascial trigger point) that persists despite the systemic plan, consider referral for local trigger-point injection.
7. For pain, fatigue, or function that remains significantly impaired despite an adequate nonpharmacologic and pharmacologic trial, refer to a multidisciplinary pain program or rheumatology.
8. Throughout, distinguish a genuine partial response — a real, clinically meaningful improvement that falls short of complete resolution — from true treatment failure; accepting a well-documented partial response as a treatment success, rather than escalating indefinitely toward complete pain resolution, is itself part of appropriate management.

• Treating fibromyalgia primarily with escalating NSAID or opioid therapy instead of the evidence-based nonpharmacologic-first, adjunct-pharmacotherapy approach.
• Starting an opioid, including tramadol, as first-line therapy rather than reserving it for after nonpharmacologic and 1st-line drug therapy have been tried.
• Dismissing the diagnosis as not real or purely psychological — this undermines the therapeutic alliance and reduces engagement with the nonpharmacologic foundation that drives most of the benefit.
• Prescribing amitriptyline at an antidepressant-range dose instead of the much lower fibromyalgia-specific titration (start 5 mg, maximum 50 mg).
• Setting an expectation of complete pain resolution with pharmacotherapy rather than a modest, adjunctive reduction alongside the nonpharmacologic foundation.
• Continuing an ineffective or no-longer-beneficial medication indefinitely instead of periodically reassessing and considering a trial of dose reduction.
• Missing a red-flag finding (new objective examination or laboratory abnormality, significant unexplained weight loss, suicidal ideation) and attributing it to fibromyalgia without further assessment.
• Missing or not screening for comorbid depression and anxiety, given how common they are alongside fibromyalgia.
• Combining duloxetine with tramadol or another serotonergic agent without counselling on and monitoring for serotonin syndrome.^[18]
• Deferring exercise until "the pain is better controlled" — graded exercise is foundational therapy, not something to attempt only after pain improves.
• Starting medications at standard adult starting doses instead of the lower starting doses and slower titration this patient population often needs, given increased side-effect sensitivity.

How to use this table: doses are adult doses and require patient-specific confirmation, including renal/hepatic adjustment. Select any drug name to open its complete Pharmasist Drug Database page.

Antidepressants used for fibromyalgia pain

All agents in this class share the interaction/monitoring cautions detailed in the Neuropathic Pain chapter (CYP-mediated interactions, serotonergic/anticholinergic additive effects). Doses below are the fibromyalgia-specific doses, which differ from both antidepressant dosing and general neuropathic-pain dosing.

Gabapentinoids

Both agents require dose reduction if creatinine clearance is under 60 mL/min and carry an additive sedation/respiratory-depression risk with opioids or other CNS depressants — see Neuropathic Pain chapter for full class detail.

Muscle relaxant

Opioid analgesics — reserved for special-situation use only, not routine therapy

No opioid, including tramadol, is recommended as first- or second-line fibromyalgia therapy. Opioids other than tramadol have no supporting evidence for fibromyalgia pain and are not included in this table for that reason — see Pharmacologic Treatment Options and Choose Initial Treatment for the explicit avoid guidance.

Cannabinoid — no established fibromyalgia benefit

Included because patients frequently ask about or already use it, not because it is recommended.

Sedative-hypnotic for severe sleep disruption (does not treat pain)

Local injection for a focal myofascial pain generator

Specialist/physician-administered — not a pharmacist-initiated therapy, and not a treatment for fibromyalgia itself.