Itching

Itching, also known as pruritus, is the major symptom of skin disease and is unique to skin and (less commonly) mucosae. It is a cause of great distress to patients. The pathophysiology of itch is complex, with a range of inflammatory mediators being implicated. Itch is not a diagnosis and itchy patients always need careful evaluation. Itch can be associated with a rash or can occur on normal skin. Some rashes such as lichen planus are characterized by severe pruritus. It is important to detect signs of subtle inflammatory skin disease because a patient presenting with generalized itch in the absence of any rash needs to be investigated for underlying systemic causes. Systemic disease associated with itch includes malignancy, both haematological and solid tumours, renal, hepatic and thyroid dysfunction and infections. Treatment of itch is difficult, with a range of topical, physical and systemic treatments used.