- Clinical science
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 → 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.
- Initiating factors
- Location: generalized vs. localized
- Onset: acute vs. chronic (> 6 weeks); time of day ; season
- Travel and environmental history
- Underlying disorders and medications
- Psychiatric history
- Substance use
- Skin examination
General physical examination
- Goal: Determine if there is evidence of an underlying disease.
Further evaluation depends on presentation and examination findings.
- Generalized pruritus
- Localized pruritus
- Skin disorders
- Medical therapy
- Systemic diseases
- Degeneration/compression of sensory nerve fibers
- Recurrent skin picking resulting in lesions and significant distress or impairment in daily functioning. Involves repeated attempts to decrease or stop picking.
- Usually begins in adolescence.
- The majority of affected individuals are female and often have comorbid obsessive-compulsive disorder, trichotillomania, or major depressive disorder.
- Substance use disorder
- Excoriation disorder
- Miscellaneous: advanced age
The differential diagnoses listed here are not exhaustive.
Secondary pruritus requires treatment of the underlying disease.
General and symptomatic measures
- Nonpharmacological: Moisturizers and/or calamine lotion (topical skin moisturizer)
- Topical application of glucocorticoids, calcineurin inhibitors, capsaicin, antihistamines, and anesthetics
- Systemic use of:
- Specific measures