π§ When to suspect
Generalised pruritus (itch) is the urge to scratch affecting widespread areas of skin. The clinically important presentation is itch without a primary rash β where the only skin findings are secondary to scratching (excoriations, lichenification, prurigo nodules). The task in primary care is threefold: look for an underlying systemic cause, review the drug history, and recognise the neuropathic and idiopathic patterns that need a different approach.
It is common: roughly 1 in 6 adults experience significant itch, rising sharply in older people, where dry skin (xerosis) is the usual culprit. Most chronic itch without a rash is benign, but a minority is the first sign of iron deficiency, renal or hepatic disease, thyroid dysfunction, or a haematological malignancy β sometimes preceding other features by months or years. Around half of chronic cases remain idiopathic after a full work-up.
| Where the itch comes from | Pattern / clue |
|---|---|
| Skin (pre-rash or subtle) | Xerosis/asteatotic eczema, scabies (burrows, household contacts), urticaria, pre-bullous pemphigoid. |
| Iron & haematological | Iron deficiency (itch even without anaemia), polycythaemia vera (itch after a warm bath), lymphoma. |
| Hepatic (cholestatic) | Primary biliary cholangitis, drug cholestasis, obstruction β itch with a raised ALP; severe in pregnancy. |
| Renal | Chronic kidney disease (uraemic pruritus), typically advanced/dialysis. |
| Endocrine / metabolic | Thyroid disease (hyper- or hypo-), diabetes mellitus. |
| Drugs | Opioids, statins, ACE inhibitors, NSAIDs, antimalarials β often with no rash. |
| Neuropathic | Localised, burning/tingling itch β brachioradial pruritus, notalgia paraesthetica, post-herpetic. |
| Psychogenic / idiopathic | Senile (age-related) itch and idiopathic pruritus β a diagnosis of exclusion. |
Source: BAD generalised pruritus guideline (2018) Β· NICE NG12
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