Fibromyalgia is diagnosed by counting symptoms, and that explains the fight

When federal researchers applied a fibromyalgia symptom checklist to a 2012 national health survey, they found that about 1.75% of American adults met the criteria, roughly 3.9 million people. The surprise came next. Of the people who met the criteria, 73% had never been told by a doctor that they had fibromyalgia; many carried other labels, such as arthritis or low back pain.

The mistake runs in the other direction too. A 2021 paper co-written by F. Wolfe, lead author of the American College of Rheumatology’s fibromyalgia criteria, notes that in population studies about three in four people who report a doctor’s diagnosis of fibromyalgia do not meet the current criteria.

Both errors trace back to one fact. Fibromyalgia is diagnosed by counting and scoring symptoms, not by a blood test, a scan or, any longer, by pressing on sore spots. That single fact explains how the diagnosis works today and why its legitimacy has been argued over for three decades.

Tender points gave way to a symptom score

Fibromyalgia rose to prominence with the American College of Rheumatology’s (ACR) 1990 criteria, and those were physical: they relied on a tender point rule, in which a clinician pressed on set spots on the body and counted the ones that hurt.

In 2010, a team led by Wolfe at the National Data Bank for Rheumatic Diseases in Wichita, Kansas, published the ACR’s preliminary diagnostic criteria, built so that no tender point examination was needed. Studying 829 patients and comparison subjects, the team found that about a quarter of people already diagnosed with fibromyalgia did not satisfy the 1990 rule. The new approach rested on two numbers instead: how many body regions hurt, and how severe the other symptoms were.

The 2016 revision, the version clinicians use now, starts with time. Symptoms have to have been generally present for at least three months. The pain has to be generalized, meaning it shows up in at least four of five broad body regions; jaw, chest and abdominal pain don’t count toward that test.

Then come the two scores. The widespread pain index counts painful areas out of 19. The symptom severity scale runs from 0 to 12: up to 9 points for how bad fatigue, unrefreshing sleep and thinking problems are, plus a point each for headaches, lower belly pain or cramps, and depression over the past six months. A pain index of 7 or more with a severity score of 5 or more qualifies, and so does a pain index of 4 to 6 with a severity score of 9 or more.

Two more changes matter to patients. The 2016 authors removed what they called a confusing recommendation about diagnostic exclusions, and fibromyalgia can sit alongside other conditions: when the 2021 study applied the criteria to 11,378 people with rheumatoid arthritis in a US databank, 21% met them. The 2016 authors also said the self-report version of the criteria works for research but is not valid for diagnosing an individual patient. A clinician’s assessment is still the diagnosis.

The ACR’s fibromyalgia page for patients, last updated in February 2025, adds that fibromyalgia does not cause abnormalities on x-rays or blood tests. Those tests are used to look for other causes, such as thyroid problems or inflammatory diseases.

How common it is, and who gets counted

Estimates depend on method. The 2012 survey analysis, led by researchers at the National Center for Complementary and Integrative Health and published in PLoS One in 2015, used a weighted sample of 8,446 people representing 225.7 million US adults. The people it identified reported heavy pain, many other symptoms, psychological distress, high medical costs, and Social Security and work disability.

A Centers for Disease Control and Prevention (CDC) page, last reviewed in 2022 and now served from the agency’s archive site, put the figure at about 4 million adults, or 2%. The ACR’s patient page says 2% to 4% of people, usually women.

Women do predominate, but by how much depends on who is looking. In clinic-based studies, about 95% of people with fibromyalgia are women. Population studies using modern criteria find about 60%. The 2021 authors argue that when doctors diagnose by overall impression, women get over-diagnosed, men get under-diagnosed, and psychological symptoms get too much weight.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) says fibromyalgia can affect any age, children included, though it usually begins in middle age. It occurs in all racial and ethnic groups and tends to run in families. Rheumatoid arthritis, lupus, ankylosing spondylitis, osteoarthritis, chronic back pain, irritable bowel syndrome, and depression or anxiety may all raise the risk.

The archived CDC page also describes the toll. People with fibromyalgia were twice as likely to be hospitalized and more than three times as likely to have major depression as adults without it. Death rates from suicide and injuries were higher, though overall mortality was similar to the general population.

Why its legitimacy is still argued over

The fight is real, and its own architects describe it plainly. The 2021 paper calls fibromyalgia much debated and controversial, notes that some physicians question whether it is a real disorder at all, and describes it as a constructed disorder: a diagnostic name for a cluster of widespread pain, many bodily symptoms, fatigue, poor sleep and mental fogginess. There is no gold standard to check it against, the authors add, and committees have set and reset its definition several times.

Constructed is easy to misread. It describes how the label’s boundary was drawn, by expert agreement, because no lab marker exists to draw it. It says nothing about whether the symptoms are genuine.

On that question, federal and professional sources are direct. NIAMS says people with fibromyalgia have heightened sensitivity to pain and that brain imaging shows altered signaling along the pathways that carry pain. The ACR’s patient page says fibromyalgia is not an inflammatory or autoimmune disease and that research points to the nervous system. The nervous-system amplification thought to drive this is unpacked in our article on central sensitization.

The cost of doubt shows up in patients’ accounts. A 2025 metasynthesis from the University of Milan pooled 12 qualitative studies. Stigma grew out of disbelief about invisible symptoms, long waits for a diagnosis and gender stereotypes aimed especially at women. People coped by hiding the illness, controlling what they told others and withdrawing, and the stigma eroded their trust in health care professionals.

What the treatment evidence shows

Exercise leads, modestly

The most detailed guideline comes from Europe. In 2016, a group from 12 countries working for the European League Against Rheumatism (EULAR), led from the University of Aberdeen and including two patient representatives, weighed 107 systematic reviews and meta-analyses. Its summary is blunt: “the only ‘strong for’ therapy-based recommendation in the guidelines was exercise.”

The therapies in its next steps were all rated weak for, and the group laid them out in order. Education and non-drug care come first. If those don’t help, the plan is tailored: psychological therapy for low mood or unhelpful coping, medication for severe pain or sleep problems, and a multimodal rehabilitation program for severe disability. The authors cautioned that most treatments produce fairly modest benefits.

The exercise effect is real but small. A 2017 Cochrane review of 13 trials with 839 people found that, compared with no exercise, aerobic training probably improved quality of life by about 8 percentage points and may have eased pain by about 11 points and improved physical function by about 10, on 100-point scales. It made little difference to fatigue or stiffness, and most trials never measured side effects, so the reviewers could not judge safety. Pacing and how to build activity without flares belong to the library’s entries on graded activity and on pacing.

EULAR also rated as weak for acupuncture, hydrotherapy, mindfulness, cognitive behavioral therapy (CBT) and meditative movement such as tai chi, qigong and yoga. It rated anti-inflammatory painkillers and massage weak against. It came out strongly against strong opioids, corticosteroids and, on safety grounds, chiropractic. EULAR is a European body. On the US side, the ACR’s patient page, which is patient education rather than a guideline, calls exercise the most effective treatment and says opioids and sleep medicines such as zolpidem are not recommended. The same page says acupuncture, chiropractic and massage can help, a kinder view of chiropractic and massage than EULAR’s ratings.

On the library’s evidence scale, exercise is recommended by name in a guideline, with modest measured effects.

Four approved drugs, and the fine print

The Food and Drug Administration (FDA) has approved four drug products for fibromyalgia, and each comes with conditions.

• Pregabalin, an anticonvulsant, lists fibromyalgia among its indications. Its extended-release form does not: that label says effectiveness for fibromyalgia has not been established.
• Duloxetine, a serotonin and norepinephrine reuptake inhibitor (SNRI), is approved for fibromyalgia in adults and in teens 13 and older.
• Milnacipran, another SNRI, is approved for fibromyalgia but not for use in children or teens. Its label carries a boxed warning that antidepressant-class drugs raised the risk of suicidal thinking and behavior in children, teens and young adults in short-term studies.
• Cyclobenzaprine under the tongue, approved in August 2025, is the newest. Ordinary cyclobenzaprine tablets are approved only for short-term muscle spasm, for up to two or three weeks.

EULAR rated pregabalin, duloxetine and milnacipran, along with low-dose amitriptyline, tramadol and cyclobenzaprine, weak for, mainly for severe pain or sleep disturbance.

The new tablet dissolves under the tongue at bedtime. Its label describes three 14-week trials in adults aged 18 to 65. On a 0-to-10 daily pain scale, the drug beat placebo by 0.4 points in one trial and by about 0.7 in another, while the third found no statistically significant difference. In the maker’s phase 3 trial, published in Pain Medicine in 2026 with four of its six authors employed by the company, 23.4% of people on the drug reported numbness in the mouth, against 0.4% on placebo. A 2025 meta-analysis of four trials and 1,684 people found more people on the drug reached a 30% cut in pain, but no significant gain on an overall fibromyalgia impact questionnaire.

The labels’ warnings matter as much as the trial numbers. The sublingual label calls for a pregnancy test before starting in women who could become pregnant, plus contraception during treatment and for two weeks after, because animal studies showed possible neural tube defects. It warns of serotonin syndrome when combined with other serotonergic drugs, and rules out use with monoamine oxidase inhibitors, during recovery from a recent heart attack, and with heart rhythm problems, heart failure or an overactive thyroid. Duloxetine and milnacipran also cannot be combined with monoamine oxidase inhibitors. Whether any of these fits a particular person, alongside everything else they take, is a decision for the prescriber and pharmacist.

A prescription app, authorized in 2023

On May 9, 2023, the FDA granted a De Novo request, creating a new device type, for a smartphone program delivering acceptance and commitment therapy (ACT), a form of CBT. Federal regulations now define a computerized behavioral therapy device for fibromyalgia symptoms as a prescription device in Class II, which requires clinical data on symptom improvement and side effects.

Its phase 3 trial, PROSPER-FM, appeared in The Lancet in July 2024. At 25 US community sites, 275 adults (257 women and 18 men) used either the 12-week program or a comparison app offering symptom tracking and educational material. At 12 weeks, 71% of the ACT group said they had improved, against 22% of the comparison group, and no device-related safety events were reported.

The fine print: the device’s maker funded the trial, and six of the 16 authors worked for the company. Participants were told they would get one of two potentially effective therapies, but research staff knew who got which, and the main outcome was each person’s own sense of improvement. On the library’s scale, that is positive evidence with a contested interpretation. How ACT and CBT perform for pain more broadly is covered in our guide to psychological pain treatments.

Small nerve fibers: a real finding, often overstated

One line of research pushes back hard on the idea that fibromyalgia is imaginary. A meta-analysis published online in 2018 by researchers at the University of Liverpool pooled 8 studies with 222 participants and found small fiber pathology, damage or loss in the thin nerve fibers that carry pain and temperature, in 49% of people with fibromyalgia. Skin biopsies found it in 45%, and imaging of nerve fibers in the cornea found it in 59%. Results varied considerably from study to study.

A review published in December 2024 by neurologists at University Hospital Würzburg in Germany says about half of women with fibromyalgia have fewer nerve fibers in the skin, a finding repeated across regions. When the loss is generalized, symptoms tend to be more severe. Whether nerve changes in the body or in the brain come first is unresolved.

The same review sets a limit: “reduced skin innervation in fibromyalgia must not be confused with small fiber neuropathy…” Small fiber neuropathy is a separate disease. A 2025 study from Sapienza University in Rome compared skin biopsies from 73 people with fibromyalgia and fiber loss against 134 people with small fiber neuropathy. The loss was significantly milder in fibromyalgia, and the authors judged that nerve damage in the body likely contributes only a limited amount.

A 2025 Danish study of 46 women with fibromyalgia showed how easy it is to over-read the signals. Depending on the questionnaire, 20 to 43 of them scored in a range suggesting nerve damage or autonomic dysfunction, problems with the nerves that run heart rate and blood pressure. Full testing confirmed small fiber neuropathy in one woman and definite cardiovascular autonomic neuropathy in two.

So both popular beliefs fall short. Fibromyalgia is not all in the head, and it is not a nerve disease that a biopsy proves. Whether reduced nerve fibers cause the symptoms is, on the library’s scale, insufficient evidence so far.

Preparing for an evaluation, and when not to wait

Because the diagnosis rests on history and symptoms, what you bring shapes the result. A useful packet includes:

• A pain map with dates. Mark every area that hurts and roughly when each started, since the criteria count regions and require three months.
• The symptoms beyond pain. Sleep, thinking, headaches, gut symptoms and mood all feed the severity score.
• Your other diagnoses. Arthritis and lupus can coexist with fibromyalgia, and thyroid and inflammatory diseases are among the causes clinicians test for.
• Every medicine and supplement. Several fibromyalgia drugs can interact dangerously with other medicines that affect serotonin, including some antidepressants.

When a treatment plan is offered, a few questions turn it into information:

• Which criteria did you apply, and what else did you check for?
• What role will activity play, and what happens if it triggers a flare?
• For any medicine, how much improvement did trials show, and what are the side effects and interactions with what I already take?
• For an app or therapy, what was it compared with in testing?
• What change would make you look again at the diagnosis?

When to get help sooner

A fibromyalgia label covers the symptoms already assessed, not every new one. New features of another condition deserve a look from whoever manages it, since fibromyalgia can coexist with other diseases. Numbness, burning or tingling in the feet, or nearly fainting on standing, are worth raising explicitly; whether nerve or autonomic testing makes sense is a question for a neurologist. Pregnancy plans and any new heart rhythm problem are questions for the prescriber, because the drug labels address both.

Depression is common with fibromyalgia, and suicide rates are higher. If pain has brought thoughts of suicide, call or text 988 to reach the 988 Suicide & Crisis Lifeline, which is free, confidential and open around the clock. If you are in immediate danger, call 911.

The most useful thing to know

Fibromyalgia is a label drawn by agreement around a real, measurable pattern, because no lab test exists to draw it. That cuts both ways. A normal blood test does not make the pain imaginary, and a fibromyalgia label should not end the search when something new appears.

The treatments help, modestly: exercise has the strongest guideline backing, and the newest drug and the prescription app showed small or self-rated gains in trials run or funded by their makers. The single most useful question at any appointment is the one the diagnosis depends on: what criteria were applied, and what else was ruled out?

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