What fibromyalgia is
Fibromyalgia is a chronic condition characterised by widespread musculoskeletal pain, fatigue, sleep disturbance and cognitive symptoms ("fibro fog"). It is recognised in the NHS and in NICE's chronic primary pain guideline NG193, which treats chronic primary pain as a condition in its own right rather than a symptom of something else that hasn't been found yet.
The 2016 ACR criteria
The most widely used clinical criteria are the 2016 update of the American College of Rheumatology criteria. In summary, three things need to be true:
- Generalised pain — in at least 4 of 5 body regions (left and right upper, left and right lower, axial).
- Symptoms for at least 3 months.
- A defined level of widespread pain and symptom severity, calculated from the Widespread Pain Index (WPI) and Symptom Severity Scale (SSS) — these score things like fatigue, waking unrefreshed, and cognitive symptoms.
Importantly, a diagnosis of fibromyalgia is valid regardless of other diagnoses — it doesn't require ruling out everything else first.
The UK NHS pathway
In England, NICE NG193 supports primary care diagnosis of chronic primary pain (including fibromyalgia-pattern) once other contributing conditions have been considered. The typical sequence:
- GP appointment focused on the pain pattern, fatigue, sleep and cognition.
- Examination and a panel of bloods to rule out other causes.
- Either GP diagnosis under NG193, or referral to rheumatology for confirmation if findings are unclear.
- Management plan covering exercise, sleep, pain self-management, and (per NG193) careful consideration of antidepressants — but not opioids or paracetamol/NSAIDs as primary chronic pain treatment.
Tests that rule other things out
- FBC, U&E, LFTs, bone profile.
- ESR and CRP (inflammation).
- TFTs (thyroid).
- Vitamin D, B12, ferritin.
- Rheumatoid factor / anti-CCP if inflammatory arthritis is suspected.
- ANA if connective tissue disease is suspected.
- Consideration of obstructive sleep apnoea screening if waking unrefreshed and snoring.
What to ask your GP
- For your bloods to be reviewed against the list above.
- To consider fibromyalgia under the 2016 ACR criteria, in line with NICE NG193.
- If the diagnosis isn't made in primary care, referral to rheumatology to confirm or exclude.
- For a written care plan addressing pain, fatigue, sleep and cognition.
If your GP won't engage with the diagnosis, a formal letter that names NG193 and the ACR criteria is usually what unlocks the conversation. Finally Seen writes that for £49.
Frequently asked questions
›What test diagnoses fibromyalgia?
There is no single blood test or scan. Fibromyalgia is a clinical diagnosis based on the pattern and duration of widespread pain, fatigue, sleep and cognitive symptoms — most commonly using the 2016 American College of Rheumatology (ACR) criteria.
›Does the NHS use the ACR criteria?
Yes — UK rheumatology services typically use the 2016 ACR criteria (widespread pain index plus symptom severity scale, symptoms for at least 3 months) or related criteria. NICE has not published a dedicated fibromyalgia guideline but its chronic primary pain guideline (NG193) applies.
›Do I have to see a rheumatologist?
Not always. NICE NG193 explicitly supports diagnosis in primary care for chronic primary pain conditions when other conditions have been ruled out. Some GPs are comfortable making the diagnosis; others refer to rheumatology to confirm and exclude other causes.
›What other conditions get ruled out first?
Typically: inflammatory arthritis (rheumatoid, psoriatic), hypothyroidism, vitamin D deficiency, polymyalgia rheumatica, lupus, hypermobility spectrum disorders, and sleep disorders. Bloods and clinical examination cover most of these.