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Pruritus

Last updated: October 25, 2020

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Pruritus is the medical term for itching of the skin. Pruritus may be generalized or localized, acute, or chronic. Localized pruritus is usually caused by dermatological conditions (e.g., allergic contact dermatitis), whereas generalized pruritus can also have systemic (e.g., uremia, hyperbilirubinemia), neurologic, psychogenic, or mixed causes. The evaluation of pruritus is based on a complete medical history and a detailed skin examination. Treatment of pruritus involves symptomatic relief and management of the underlying disease.

  • Poorly understood
  • Trigger; , i.e., mechanical, chemical, or thermal stimuli, as well as exposure to certain mediators (e.g., histamine, serotonin, prostaglandins, kinins) → activation of afferent C-fibers in the skin interpreted by the CNS as pruritus
  • Scratching and rubbing the skin stimulation of inhibitory circuits and pain receptors → decreased pruritus in the short-term (however, in many patients, scratching increases irritation and ultimately worsens itching)
  • Gate control theory: Painful input transmitted by A-fibers inhibits the transmission of pruritic input from the C-fibers.

Medical history

  • Initiating factors (e.g., contact with specific substances, drug intake, insect bites)
  • Location: generalized vs. localized (see below)
  • Onset
    • Acute vs. chronic (> 6 weeks)
    • Time of day
    • Season
  • Allergies
  • Travel and environmental history
  • Underlying disorders (e.g., polycythemia vera) and medications (e.g., chloroquine)
  • Psychiatric history
  • Substance abuse (e.g., opioids, cocaine, and amphetamines)

Physical examination

Further diagnostics

Further evaluation depends on presentation and examination findings.

Pruritus without primary skin lesions should be further investigated, as it may be a sign of a serious underlying condition like malignancy.

The differential diagnoses listed here are not exhaustive.

Secondary pruritus requires treatment of the underlying disease.

  1. Fazio SB, Yosipovitch G. Pruritus: Etiology and patient evaluation. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/pruritus-etiology-and-patient-evaluation.Last updated: September 23, 2016. Accessed: January 18, 2018.
  2. Fazio SB, Yosipovitch G. Pruritus: Overview of Management. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/pruritus-overview-of-management.Last updated: January 15, 2019. Accessed: January 29, 2019.