Reasoning GP · Algorithm · 1-page summary
Widespread itch (generalised pruritus) — adults
For: adults with generalised itch in primary care, especially itch without a primary rash. Not for: children; itch in pregnancy beyond the red flags (pruritus in pregnancy); localised perianal itch (anal itchiness).
Core rule: itch without a primary rash raises the importance of systemic causes — examine nodes, liver and spleen and run the basic screen. Itch alone is not a cancer referral criterion; nodes, splenomegaly or B-symptoms are.
0Stop — call 999 now
- Anaphylaxis — urticaria + angio-oedema with dysphagia, dyspnoea or hypotension → 999 IM adrenaline 500 micrograms (1 mg/mL) in adults, repeat after 5 min if no improvement; lie flat, legs raised (position of comfort if breathing is difficult); do not let them stand or walk.
- Blistering or peeling skin with mouth, eye or genital involvement (possible Stevens–Johnson syndrome/TEN) → 999 / A&E
- Suspected sepsis with any NICE NG253 high-risk criterion → 999 immediate emergency transfer.
- Pregnant with reduced fetal movements → Immediate maternity assessment.
1Triage — rash? duration? pregnant?
| Finding | Pathway |
|---|---|
| Acute <6 weeks | Clear skin cause (urticaria, contact dermatitis) → treat, review; no full screen |
| Chronic >6 weeks | Basic screen + tests guided by findings |
| Rash? | Primary rash → dermatological. None → systemic, drug, neuropathic, psychogenic (skin disease can still be subtle) |
2Screen — one row is enough
- Unexplained nodes or splenomegaly + itch, fever, night sweats or weight loss → consider suspected cancer pathway haematology (NG12). Unwell, severe cytopenia, hyperviscosity, fast-growing nodes → Same-day
- Jaundice → Same-day LFTs + bilirubin; + fever, RUQ pain or unwell → same-day medical. Aged ≥40 → pancreatic suspected cancer pathway
- Pregnant: generalised or palm/sole itch, worse at night, normal skin → Same-day maternity for LFTs + random bile acids
- Advanced CKD + severe itch with nausea, confusion, worsening bloods or treatment failure → Same-day renal/medical review
- Severe drug eruption or systemically unwell → Same-day assessment. Significant unexplained weight loss → assess against NG12.
- Aquagenic itch, plethora, headache, visual change → repeat FBC; persistent high counts or splenomegaly → discuss/refer haematology.
3Assess
☐ Drugs incl. OTC/herbal (opioids, ACE inhibitors, diuretics, statins) ☐ Household affected? ☐ Full skin exam: web spaces, wrists, genitals, waist (burrows), scalp, nails, mucosa, patches/plaques ☐ Nodes, liver, spleen, jaundice, thyroid
Persistent, no primary rash: FBC, ferritin/iron studies if indicated, U&E/eGFR, LFTs (bilirubin, ALP), bone profile, TFTs; CRP/ESR, urinalysis, HbA1c if indicated; more only by findings. Not routine: LDH, SPEP, ANA/ANCA, HIV, hepatitis serology or CT.
4Classify — only if the screen is negative
- Dermatological — primary lesion: eczema, psoriasis, urticaria, lichen planus, scabies → treat the skin disease.
- Systemic — no lesion: cholestasis/PBC, CKD, iron deficiency, thyroid, PV, lymphoma, drugs → treat the driver; iron deficiency → iron-deficiency pathway (itch itself does not predict GI cancer).
- Neuropathic — burning, dermatomal (brachioradial, postherpetic) → consider a gabapentinoid, with caution; antihistamines ineffective.
- Psychogenic — diagnosis of exclusion. Mixed — common in older adults (xerosis + drugs + CKD) → address each.
- Uncertain — say so; review, and refer if persistent, severe or progressive.
5Treat today — cause first, symptoms alongside
- All: liberal emollients (at least twice daily) + soap substitute; lukewarm water, short nails, cotton, avoid overheating.
- Scabies: permethrin 5% whole body (adults neck down), wash off after 8–12 h, repeat after 7 days; treat all household and close contacts at the same time; hot-wash bedding.
- Urticaria: non-sedating antihistamine (cetirizine, loratadine); if inadequate, up to 4× standard dose (off-label, documented).
- Sedating antihistamine at night: short-term, avoid or minimise in older adults. Steroid only if skin inflamed. Cholestatic itch: colestyramine with hepatology. Doses: NICE/SPC, BNF, local formulary.
6Refer routinely
- Cholestatic LFTs → hepatology/gastroenterology; raised ALP + positive AMA (PBC) → hepatology.
- Dermatology: refractory itch, diagnostic uncertainty, suspected cutaneous T-cell lymphoma, brachioradial pruritus, prurigo nodularis. Refractory urticaria → dermatology/allergy.
- Refractory uraemic itch → nephrology. Delusional parasitosis → liaison psychiatry.
7Never reassure by
- Normal-looking skin — itch without a rash needs the systemic screen.
- "Dry skin" in an older adult without excluding a systemic cause.
- Normal first LFTs or bile acids in pregnancy — ICP is not excluded if itch persists.
- "Eczema" not responding — think scabies or cutaneous T-cell lymphoma.
- Treating only the patient with scabies.
- Itch alone as a cancer trigger — but nodes, spleen or B-symptoms always count.
8Safety-net — say it, then document it
999 “Call 999 if your lips, tongue or throat swell and you struggle to breathe or swallow, or you get a blistering or peeling rash with a sore mouth, eyes or genitals.” Same day: “Contact us today for new lumps in the neck, armpit or groin, yellow skin or eyes, fever with night sweats, significant weight loss, or itch after hot showers with headache or sight change. If pregnant: itch, especially palms and soles → maternity today; reduced baby movements → maternity immediately.”
Follow-up: review response and any new systemic symptoms, sooner if severe; repeat tests only if itch persists, examination changes, results were borderline or new features appear. Scabies itch can last weeks; new burrows = treatment failure.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies; pregnancy asked
Rash or no rash recorded after a full skin exam
Nodes, liver, spleen and jaundice checked
Basic screen if persistent without rash; drugs reviewed
Written safety-net and review booked
Summary of the full Reasoning GP widespread itch algorithm, which holds the detail, management and evidence. Sources: IFSI classification; NICE NG12 (updated April 2026), NG253, TA890; PCDS; BAD 2018; RCOG Green-top 43; BSH 2019; BSG 2021. Clinical reference — follow local policies and check doses: NICE/SPC, BNF.