Reasoning GP · Algorithm · 1-page summary
Medically unexplained (functional) symptoms
For: persistent physical symptoms not adequately explained by structural disease: FND, chronic primary pain, fibromyalgia, IBS, ME/CFS, health anxiety. Not for: a new symptom not yet assessed (use that symptom's algorithm first). Children: think of fabricated or induced illness (block 2).
Core rule: a functional diagnosis is positive, not "nothing wrong" — validate, explain, one targeted screen. But a functional label never explains a new objective sign, weight loss or night sweats: assess these as a new presentation.
0Stop — act now — the functional label does not change these
- Sudden-onset focal neurological deficit → 999 stroke pathway, even with known FND.
- Suicidal thoughts with immediate danger → 999. Active ideation without immediate danger → Same-day local urgent mental-health / crisis pathway.
- Child in immediate danger from fabricated or induced illness → children's social care or police 999 now.
1Triage — what has changed since the last assessment?
| Change | Action |
|---|---|
| Danger now | Block 0 → 999 |
| New objective sign | New neurological sign, unable to eat, drink or mobilise, acute psychiatric episode → Same-day |
| New systemic feature | Unexplained weight loss, night sweats, new pattern → investigate as a new presentation |
| Stable, nothing new | No new tests; document why. Planned review as agreed. |
2Screen — do not miss organic disease or risk
- New or progressive UMN, cerebellar or cranial nerve signs → Same-day acute medicine or neurology. FND and organic disease coexist.
- Weight loss and anorexia, night sweats (cancer, IBD, adrenal insufficiency) → investigate, whatever the label.
- First multi-system presentation in an older adult → lower threshold (paraneoplastic, autoimmune encephalitis, neurodegeneration).
- Rapid loss of mobility, eating, drinking or self-care → Same-day assessment, then MDT review.
- Depression, self-harm, hopelessness → ask directly: thoughts, intent, plans, means, protective factors. PHQ-9 item 9 is only a prompt.
- Child, repeated unexplained symptoms, parent driving investigation → Same-day safeguarding lead and paediatric safeguarding referral.
3Assess — once, properly
☐ Full relevant examination at first presentation; document it ☐ FND positive signs: Hoover's sign, give-way weakness, non-dermatomal sensory loss ☐ PHQ-9 / GAD-7 if mood or anxiety suspected ☐ One symptom-directed screen: FBC, ferritin, CRP/ESR, U&E, LFTs, calcium, TFTs, HbA1c, B12/folate, coeliac serology as the pattern fits
Not: tests "to reassure", repeats of normal tests, parallel specialty referrals, one MRI for every neurological symptom.
4Classify — the most specific positive label
- FND — positive, internally inconsistent signs → explain the signs; FND rehabilitation (physio, OT, SLT, psychology) (NG252).
- Chronic primary pain / fibromyalgia → supervised group exercise, staying active; consider ACT or CBT (NG193).
- IBS → diet, soluble fibre, symptom-targeted drugs (CG61). Rectal bleeding, iron deficiency, weight loss, nocturnal symptoms, mass → reassess.
- ME/CFS → flexible energy management; ME/CFS specialist team (NG206).
- Health anxiety → CBT via NHS Talking Therapies; agree no repeat tests and planned, not crisis-driven, appointments.
- Uncertain — the work-up may be incomplete. Say so; agree what would trigger re-investigation.
5Treat today — the consultation is the treatment
- Validate and explain: "Your symptoms are real"; a functional mechanism, never "all in your head", "stress" or "nothing wrong".
- Written co-produced plan: functional goals, one screen and no repeats, review schedule, re-investigation criteria.
- Chronic primary pain, aged 18+: consider an antidepressant (amitriptyline, citalopram, duloxetine, fluoxetine, paroxetine, sertraline); start low; review at 4–6 weeks, stop if ineffective.
- Do not start gabapentinoids, opioids, NSAIDs, paracetamol or benzodiazepines for chronic primary pain. Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- Anxiety, depression, health anxiety, chronic pain → NHS Talking Therapies (self-referral possible).
- FND → neurology and FND rehabilitation. ME/CFS → specialist team. Fibromyalgia → rheumatology or pain only if uncertain or complex; IBS → gastroenterology if atypical.
- Severe (housebound, job loss, frequent attendance) or psychiatric comorbidity → functional symptoms MDT / liaison psychiatry.
7Never reassure by
- An existing FND or "MUS" label when there is a new objective sign.
- Normal tests alone ("all normal") with no functional explanation.
- Repeating normal tests to settle anxiety.
- An old screen when weight loss or night sweats are new.
- Assuming a functional diagnosis lowers suicide risk.
- Graded exercise or fixed activity increases in ME/CFS.
8Safety-net — say it, then document it
999 “Call 999 for sudden weakness, numbness, a drooping face or loss of speech, or if you feel you may act on thoughts of ending your life.” Same-day “Contact us today for new weakness or unsteadiness, or if you cannot eat, drink or get about.” Earlier review: “Book an earlier appointment, not the next planned one, for weight loss you can't explain, night sweats or a clear change in your symptoms.”
Follow-up: planned reviews at agreed intervals by severity, risk and preference, not crisis-driven; 4–6 weeks after starting an antidepressant or therapy referral.
✓Safe to manage in primary care only if — all five, documented
No block 0–2 item applies
Examination and one targeted screen documented
Specific positive label explained, or uncertainty stated
Written plan: review date and re-investigation criteria
Mood and suicide risk considered; safety-net given
Summary of the full Reasoning GP medically unexplained symptoms algorithm, which holds the detail, communication scripts, lifestyle advice and evidence. Sources: NICE NG193, NG206, CG61, NG252; RCP fibromyalgia guidelines (2022); RCPsych/RCGP MUS guidance. Clinical reference — follow local safeguarding and crisis pathways and check doses: NICE/SPC, BNF.