# 037 Pruritus, 2nd ed

FAST FACTS AND CONCEPTS #037 PDF


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

Background  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.

Common Causes

  • Dermatological (dryness, wetness, irritation, eczema, psoriasis)
  • Metabolic (hepatic failure, renal failure, hypothyroidism)
  • Hematologic (iron deficiency, polycythemia, thrombocytosis, leukemia, lymphoma)
  • Drugs (opioids, aspirin, drug reactions)
  • Infectious (scabies, lice, candida)
  • Allergy (urticaria, contact dermatitis, drug reactions)
  • Psychogenic

Management Management of pruritus involves eliminating the cause when possible. Symptomatic strategies include:

  • 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 and/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 not much supporting research, many report benefits of combining H1 and H2 receptor subtype antihistamines. These may have central effects as well as peripheral antihistaminergic effects. Doxepin (10-30 mg PO at bedtime), a tricyclic antidepressant, is a very potent antihistamine and may help in more refractory cases.
  • Topical steroids may be helpful in the presence of skin inflammation. These are 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 (e.g. Aveeno). More recent pharmacological treatments include cholestyramine for cholestatic pruritis, and in other selected patients, ondansetron, paroxetine or naloxone.

References

  1. Fleisher A, Michaels JR. Pruritus. Berger A, Portenoy RK, Weissman DE, eds. In: Principles & Practice of Supportive Oncology. Philadelphia PA: Lippincott-Raven Publishers; 1998: pp245-250.
  2. Krajnik M, Zylicz Z. Understanding pruritis in systemic disease. J Pain Symp Manage. 2001; 21:151-168.
  3. Wilde MI, Markham A. Ondansetron: a review of its pharmacology and preliminary clinical findings in novel applications. Drugs. 1996; 52:773-794.
  4. Zylicz Z, Smits C, Chem D, Krajnik M. Paroxetive for pruritis in advanced cancer. J Pain Symptom Manage. 1998; 16:121-124.

Fast Facts and Concepts are edited by Drew A. Rosielle MD, Palliative Care Center, Medical College of Wisconsin. For more information write to: drosiell@mcw.edu. More information, as well as the complete set of Fast Facts, are available at EPERC: www.eperc.mcw.edu.

Version History: This Fast Fact was originally edited by David E Weissman MD. 2nd Edition published August 2005. Current version re-copy-edited March 2009.

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Von Gunten CF, Ferris F. Pruritus, 2nd Edition. Fast Facts and Concepts. July 2005; 37. Available at: http://www.eperc.mcw.edu/fastfact/ff_037.htm.

Disclaimer: Fast Facts and Concepts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Facts cite the use of a product in a dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Non-Pain Symptoms and Syndromes