Itchy Skin

Most itch is skin-level: a compromised barrier loses water, nerve endings become irritable, and scratching damages the barrier further in a self-sustaining loop. Xerosis, eczema, contact dermatitis, urticaria and scabies account for the majority of cases, and the treatment logic is barrier repair plus targeted anti-inflammatory therapy. Emollients applied within minutes of a short lukewarm shower do more than any oral supplement, and the itch-scratch cycle is broken by treating inflammation properly rather than by willpower. The clinically important division is itch with a rash versus itch without one. Generalised itch on normal-looking skin, especially if persistent, should prompt bloods: iron deficiency, thyroid disease in either direction, chronic kidney disease, cholestatic liver disease and, less commonly, lymphoma and polycythaemia all cause pruritus before anything is visible. Drug causes are frequent and under-recognised — opioids, some antihypertensives and statins among them. Supplement claims here outrun the evidence. Omega-3 and evening primrose oil have been trialled repeatedly in eczema with unimpressive results; vitamin D shows a modest signal in atopic dermatitis, particularly where levels are low; and probiotics have their best data in prevention in high-risk infants rather than in treating established itch.

• •Generalised or localised itching
• •Dry, flaking or cracked skin
• •Excoriations from scratching
• •Thickened lichenified patches
• •Raised weals that come and go
• •Night-time worsening

• •Xerosis and barrier dysfunction
• •Atopic or contact dermatitis
• •Urticaria
• •Scabies
• •Iron deficiency
• •Thyroid, liver or kidney disease
• •Medications including opioids

Impaired skin barrier and low ambient humidity, atopic and contact dermatitis, urticaria and mast cell activation, scabies infestation, iron deficiency, thyroid dysfunction, cholestasis, chronic kidney disease, and drug reactions.