Home › Surgical sieve › Rash / itch
Surgical sieve
🩹 Rash / itch
Is the patient sick, is the skin peeling, and is there a new drug? Those three sort almost all of it — and remember itch with no rash at all.
| Anaphylaxis Must exclude | Urticaria with airway, breathing or circulation compromise. Skin signs are ABSENT in up to a fifth of cases — their absence does not exclude it.IM adrenaline 500 micrograms into the anterolateral thigh, now. Do not wait for a second opinion. |
|---|---|
| Meningococcal sepsis Must exclude | Non-blanching rash in an unwell patient. Starts as a few blanching spots and is often missed early — and is harder to see on darker skin, so look at the soles, palms and conjunctivae.Blood cultures and IV antibiotics without waiting. Do not delay for LP. |
| SJS / TEN Must exclude | Painful skin, mucosal involvement (eyes, mouth, genitals), and a positive Nikolsky sign. Almost always 1–3 weeks after a new drug.Stop the culprit drug. Dermatology and burns or critical care now — this is a burn by another name. |
| Cellulitis / necrotising fasciitis Must exclude | Pain out of proportion to what you can see, rapid spread, systemic upset, bruising or crepitus. Early NF often has no skin change at all.Surgical review NOW if pain is out of proportion. Antibiotics do not treat it alone. |
| DRESS Must exclude | Widespread rash 2–8 WEEKS after a new drug, with fever, facial swelling, lymphadenopathy, eosinophilia and deranged LFTs. The long latency is why the drug gets exonerated.Stop the drug and check FBC and LFTs. Mortality is around 10% — dermatology input. |
| Erythroderma Time-sensitive | More than 90% of the skin red and scaling. Loses heat, fluid and protein like a burn; watch for hypothermia and high-output cardiac failure.Dermatology, fluid balance, keep them warm. Not a rash to review in the morning. |
| Angioedema Time-sensitive | Deep swelling of lips, tongue or face WITHOUT urticaria or itch, which points away from allergy and towards an ACE inhibitor or hereditary cause.Assess the airway first. ACE-inhibitor angioedema does not respond to adrenaline, steroids or antihistamines — stop the drug and call anaesthetics if the airway is threatened. |
| Drug eruption (morbilliform) Common | Symmetrical pink macules and papules starting on the trunk, 5–10 days after a new drug. Well patient, no mucosal involvement, normal bloods.Stop the likely culprit and look specifically for the features that would make it SJS/TEN or DRESS instead. |
| Acute urticaria Common | Itchy wheals that come and go within 24 hours, each individual lesion lasting less than a day. Often no cause is ever found.Non-sedating antihistamine. Wheals lasting more than 24 hours in one spot, or leaving bruising, is vasculitis — not urticaria. |
| Cholestatic itch Common | Intense generalised itch with NO rash except scratch marks. Worse at night, often on the palms and soles. May precede jaundice by weeks.LFTs with a split bilirubin, and an ultrasound. The itch is a liver result, not a skin one. |
| Uraemic pruritus Common | Itch with no rash in advanced CKD or on dialysis. Often worse on the back and at night, and worse after dialysis.Check the phosphate, calcium and PTH — and the adequacy of dialysis — before treating the skin. |
| Scabies Common | Ferocious itch, worse at night, with burrows in the finger webs, wrists and around the nipples or genitals. Other people in the house or bay itch too.Treat the patient AND the contacts on the same day, or it comes straight back. Infection control if on a ward. |
| Eczema / contact dermatitis Common | Itchy, dry, poorly demarcated. Contact dermatitis follows the shape of what touched it — a watch strap, a dressing, a glove.Emollient and a topical steroid of appropriate potency. Look at the distribution before blaming a drug. |
| Herpes zoster Time-sensitive | Burning pain in one dermatome that PRECEDES the rash by days, then vesicles that do not cross the midline.Antiviral within 72 hours. Ophthalmology same day if the nose tip is involved — that is the eye. |
| Iron deficiency Consider | Generalised itch with no rash, sometimes with restless legs. A well-recognised and easily-missed cause.FBC and ferritin. Treating the iron treats the itch — and then ask why they are iron deficient. |
15 differentials · 8 open a full pathway in the app.