Pruritus and sweating — Rapid | Doctor’s Passport

Synopsis

Identify causes of itch and sweating, recognise emergencies, protect skin and select mechanism-specific treatment without avoidable sedation or anticholinergic harm.

First-line assessment maps timing, triggers, rash before scratching, systemic clues, medicines and effects on skin and sleep.
Treat airway swelling, wheeze, shock or rapidly spreading urticaria as possible anaphylaxis; fever with rigors, hypotension or confusion requires urgent infection assessment.
First-line itch care uses a cool environment, soap substitute, regular fragrance-free emollient, short nails, loose cotton clothing and treatment of the primary skin disorder.
Antihistamines help urticaria and other histamine-mediated itch but usually have little direct benefit in cholestatic or uraemic pruritus; sedation is not the same as antipruritic efficacy.
For cholestatic pruritus, relieve a reversible biliary obstruction when appropriate; cholestyramine is usual first-line drug treatment and must be separated from other medicines.
Rifampicin, opioid-pathway medicines and treatments for uraemic itch require specialist selection, interaction checks and liver or renal monitoring.
First-line sweating care treats fever, pain, anxiety, withdrawal or endocrine cause and uses a fan, breathable layers, bedding changes, hydration and skin-fold protection.
Refractory sweating may justify specialist off-label treatment only after cause review and non-drug care.

Key red flags

Tongue or throat swelling, stridor, wheeze, hypoxia, hypotension or collapse with itch is anaphylaxis until proven otherwise.

Fever, rigors, hypotension, tachypnoea, confusion or reduced urine output with sweating requires urgent sepsis assessment.

Skin pain, mucosal involvement, blistering, purpura or detachment after a new medicine suggests a severe cutaneous drug reaction.

Jaundice with fever and right-upper-quadrant pain suggests ascending cholangitis and requires urgent biliary and infection management.

Drenching sweats with persistent fever, nodes, splenomegaly or weight loss raises infection or haematological malignancy.

New drowsiness, falls, myoclonus or slow breathing after gabapentin in renal impairment suggests accumulation and toxicity.

Naltrexone or another opioid antagonist can precipitate severe withdrawal and loss of analgesia in a patient receiving opioids.

Anaphylaxis or severe drug reaction

Airway swelling, wheeze, shock, mucosal erosion, blistering, skin pain or systemic illness requires emergency treatment and immediate culprit-drug review.

Investigation priorities

First-line skin and systemic historyFirst stepFirst line

Determine rash timing, distribution, water or heat triggers, contacts, jaundice, renal disease, fever, weight loss, medicines and effect on sleep.

Targeted first-line blood panelFirst line

Use full blood count, ferritin, renal, liver, calcium, glucose, thyroid and inflammatory testing when systemic disease is plausible and actionable.

Management branches

Immediate safetySeparate allergy, infection and severe drug reaction

Itch or sweating is acute with airway, breathing, circulatory, fever, mucosal or blistering features.

Use ABCDE assessment, remove likely exposure, check observations and glucose and identify anaphylaxis, sepsis, cholangitis or severe cutaneous reaction.
Give emergency treatment under the relevant pathway, stop suspect medicines when safe and obtain acute specialist help without delaying symptom relief.
Document the reaction, suspected trigger, timing, treatment and future avoidance or allergy referral and reconcile the medicine record.

Key medicines

Non-sedating antihistamine for urticariaFor histamine-mediated urticaria, cetirizine 10 mg orally once daily is a common adult regimen; adjust for renal function and follow urticaria guidance if specialist up-dosing is considered.Drowsiness can still occur and renal dose reduction may be needed; do not let antihistamine delay intramuscular adrenaline in anaphylaxis.

Cholestyramine for cholestatic pruritusBegin with 4 g orally once or twice daily and titrate under hepatology or palliative guidance; take other oral medicines at least 1 hour before or 4 to 6 hours after each dose.Constipation, bloating, poor palatability, reduced absorption of medicines and fat-soluble vitamin deficiency limit treatment; avoid in complete biliary obstruction without specialist review.

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