• Clinical science

Pruritus

Summary

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.

Pathophysiology

  • Poorly understood
  • Trigger → activation of afferent C-fibers in the skin → interpreted by the CNS as pruritus
  • Scratching and rubbing the skin → stimulates inhibitory circuits and pain receptors → decreases 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.

References:[1]

Diagnostics

Medical history

  • Initiating factors
  • Location: generalized vs. localized
  • Onset: acute vs. chronic (> 6 weeks); time of day ; season
  • Allergies
  • Travel and environmental history
  • Underlying disorders and medications
  • Psychiatric history
  • Substance use

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.

References:[1]

Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

Secondary pruritus requires treatment of the underlying disease.

References:[2]