The term pruritus is derived from the Latin prurire, which means "to itch." Pruritus is a symptom unique to skin that occurs in a multitude of dermatologic disorders, including dry skin or xerosis, atopic eczema, urticaria, and infestations. Itching also may be a sign of internal disorders, including malignant neoplasms, chronic renal failure, and hepatobiliary disease. The treatment of pruritus varies greatly depending on the underlying disorder.
General measures employing copious application of emollients usually are sufficient for xerosis. Inflammatory disorders such as atopic dermatitis, contact dermatitis, and lichen simplex chron-icus may respond better to potent topical glucocorticoids and oral doses of sedating antihistamines. Antihistamines are useful in histamine-induced pruritus and in other pruritic disorders in which the sedating effects of these drugs facilitate sleep and reduce scratching at night, when most pruritic disorders are more symptomatic.
Cholestasis-associated pruritus may respond to cholestyramine (Questran, others; see Chapter 35), ursodeoxycholic acid (actigall, others; see Chapter 37), ondansetron (zofran; see Chapter 37), or rifampin (see Chapter 47). Recently, nalmefene (revex) (20 mg twice per day) has been shown to be effective in cholestatic pruritus.
The pruritus of uremia is treated most effectively with UVB radiation. Prurigo, a ubiquitous disorder associated with itchy nodules of the skin, is notoriously difficult to treat. In addition to topical and intralesional steroids, prurigo may respond to the opioid antagonist naltrexone (see Chapter 21) at a dose of 50 mg/day or to the proton pump inhibitor omeprazole (see Chapter 36).
Gold will ameliorate the itching palm (see Chapter 26) but the relief is generally only temporary.
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