Fast Fact and Concept #037: Pruritus

2nd Edition

Author(s): Charles von Gunten , MD and Frank Ferris MD

Pruritus (itching) is a common and often distressing symptom near the end of life. The itch sensation may arise from stimulation of the skin itch receptor via unmyelinated C fibers, or itch may arise as a central phenomenon without skin involvement (e.g. opioid induced pruritus). Although histamine causes pruritus, many patients with pruritis show no signs of histamine release. Besides histamine, serotonin, prostaglandins, kinins, proteases and physical stimuli have all been implicated as mediators of pruritus.

Management

Management of pruritus involves eliminating the cause when possible. Common causes include: Dermatological (dryness, wetness, irritation, eczema, psoriasis), Metabolic (hepatic failure, renal failure, hypothyroidism), Hem/Onc (iron deficiency, polycythemia, thrombocytosis, leukemia, lymphoma), Drugs (opioids, aspirin, drug reactions), Infection (scabies, lice, candida), Allergy (urticaria, contact dermatitis), and Psychogenic.  

Moisturizers : Dryness (xerosis) is very common and may exacerbate other causes. The mainstay of treatment is skin hydration. Note: Most OTC preparations only have small amounts of moisturizer—they are mostly water. Serious dryness requires emollients and moisturizers (such as petroleum jelly) that patients find oily or greasy. Nevertheless, they may applied after bathing, over damp skin, with a superficial covering.

Cooling agents (e.g. Calamine or Menthol in aqueous cream, 0.5%-2%) are mildly antipruritic. They may act as a counterirritant or anesthetic. A more direct way to anesthetize the skin is with the eutectic mixture of local anesthetics lidocaine and prilocaine (EMLA cream).

Antihistamines may be helpful in relieving itch when associated with histamine release. Morphine causes non-immune mediated histamine release from mast cells. Although there is little data, many report advantages of combining H1 and H2 receptor subtype antihistamines. These may have central effects as well as peripheral antihistaminic effects. Doxepin, a tricyclic antidepressant, is a very potent antihistamine and may help in more refractory cases, 10-30 mg po qhs.

Topical steroids may be helpful in the presence of skin inflammation. These may be best applied in ointment rather than cream formulations to alleviate dryness. Systemic steroids have been used in refractory cases.

Other: An old-fashioned but effective remedy is immersion in an oatmeal bath (Aveeno). More recent pharmacological treatments include cholestyramine for cholestatic pruritis, and in other selected patients, ondansetron, paroxetine or naloxone.

References

• Alan B. Fleisher, Jr and Jason R. Michaels. Pruritus. In: Principles & Practice of supportive Oncology. Eds: Ann Berger, Russell K. Portenoy, David E. Weissman. Lippincott-Raven Publishers Philadelphia 1998;245-250.
• Krajnik M and Zylicz. Understanding pruritis in systemic disease. J Pain Symp Manage 2001;21:151-168.
• Wilde MI, Markham A. Ondansetron: a review of its pharmacology and preliminary clinical findings in novel applications. Drugs 1996;52:773-794.
• Zylicz Z, Smits C, Chem D and Krajnik M. Paroxetive for pruritis in advanced cancer. J Pain Symptom Manage 1998;16:121-124.

This Fast Fact was edited by David E. Weissman, MD; Palliative Care Center, Medical College of Wisconsin. For comments/questions write to the current editor, Drew Rosielle, MD at: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: Fast Facts and Concepts #37 Gunten CF, Ferris F. Pruritis; 2nd edition, August 2005. End-of-Life Palliative Education Resource Center www.eperc.mcw.edu.

Creation Date: 3/2001; 2nd edition, August 2005.

Purpose: Instructional Aid, Self-Study Guide, Teaching

Audience(s)

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Non pain symptoms & syndromes