Occurrence

Chronic pruritus is a frequent symptom in the general population. It can occur at any age, but most patients are older. Many patients have comorbidities. Women and men differ in age at the onset of chronic pruritus (men are older), the underlying causes, clinical appearance and symptom handling.
 
Pruritus can occur in various forms:

Group 1: Pruritus on primarily diseased/inflamed skin
Group 2: Pruritus on unaffected skin (not inflamed)
Group 3: Pruritus with chronic secondary scratch lesions

The following diseases can cause pruritus: dermatological diseases, systemic diseases including pregnancy diseases and drug-induced pruritus, neurological and psychiatric diseases.

Some patients are diagnosed with more than one cause of pruritus, while others are diagnosed with no underlying disease. The origin of pruritus is unknown in 8–15% of affected patients.