The landmark international consensus now recognises pruritus not just as a symptom, but as a disease in its own right.
For the first time in more than 360 years, the medical definition of pruritus has been given a modern medical identity.
Dermatologists, neuroscientists and patient advocates from around the world have spearheaded the new definition that moves beyond the simplistic “urge to scratch” to embrace the full complexity of what millions endure every day.
The two-phase Delphi consensus involved stakeholders from 35 countries and resulted in a new definition that reflects the nuanced emotional, physiological and temporal dimensions of both acute and chronic itch.
Their new definition has been published in the Journal of the European Academy of Dermatology and Venereology.
“The new pruritus definition is expected to improve communication with patients, health authorities and other stakeholders and to facilitate the development of itch-specific therapies independent of the initial trigger,” the authors wrote.
The redefinition is the first major update since the original 1660 description by German physician Samuel Haffenreffer, who defined itch simply as “an unpleasant sensation that causes the desire to scratch”.
“In two Delphi rounds, two statements defining the itch sensation and nine defining chronic pruritus as a disease achieved consensus,” the authors wrote.
“The definition of pruritus as an unpleasant sensation commonly triggering an urge to scratch mentions that external or internal factors can trigger, worsen or improve pruritus. Chronic pruritus is described as a symptom of diseases but also as an independent disease. The definition of chronic pruritus includes temporal, physiological, causal and quality of life aspects.”
Key additions to the definition include:
- Itch as a Sensory Experience: The new definition describes itch as “an unpleasant sensation of the skin and/or neighbouring mucous membranes commonly triggering an urge to scratch”. The term unpleasant was chosen deliberately over “irritating” or “aggravating,” which were seen as too weak or misleading.
- External and Internal Triggers: Itch is acknowledged as a complex response to a wide array of internal and external stimuli, including chemical, thermal, visual, auditory, psychological and pharmacological factors.
- Chronic Pruritus as a Disease: A key advancement is the recognition of chronic pruritus (CP) – defined as lasting more than six weeks – as not just a symptom but a standalone disease.
- Neurological and Emotional Components: Chronic pruritus is linked to structural and functional changes in the nervous system, comparable to chronic pain. The definition acknowledges the psychological burden, social isolation and even depression caused by chronic itch.
- The Itch-Scratch Cycle: The new statements describe how scratching may provide short-term relief but often leads to worsening symptoms, forming a vicious itch-scratch cycle. Scratching can also be experienced as rewarding or even pleasurable — a point previously neglected in clinical literature.
The need for the new definition was highlighted at the annual meeting of the International Dermatology Outcome Measures (IDEOM) organisation in June 2022, where patients voiced frustration that their suffering was invisible in current medical literature.
“Patients missed the emotional component referring to quality of life,” the authors wrote.
“Considering the high prevalence of pruritus (up to 25% to 40%) in the general population and its impact on quality of life, a more precise definition of the sensation appeared necessary.
“Consequently, an initiative was formed to reach a consensus on a new definition of human-experienced itch using the experience of global itch experts, health authority members and patients through a Delphi process.”
A final check for comprehensibility of the statements was performed with 19 CP patients from Europe (Germany, Greece, Luxembourg, Netherlands, United Kingdom), North America (Canada, USA) and Australia recruited with the help of the societies and the patient organisation GlobalSkin.
The final definition will now be translated into multiple languages and promoted across professional societies and health agencies. The team also plans to incorporate the new terminology into clinical guidelines and educational materials.
“This Delphi process led to an international, multidisciplinary consensus on an updated definition of pruritus, which better reflects the complexity of the sensation, including symptoms and time course, as well as emotional impact and causal aspects,” the authors concluded.
“The new definition separately addresses itch sensation and disease. While the first part clarifies the original definition and relates mainly to acute pruritus, the characterisation of CP as a disease is new and significant.
“It separates the sensation from the initial cause, considering it an independent disease, as it has already been implemented for pain. Pruritus is devastating, and the new definition sets out to facilitate healthcare, communication with decision-making bodies, and, importantly, the first step towards researching and developing suitable treatments, including targets beyond the initial triggers.”
Journal of the European Academy of Dermatology and Venereology, July 2025
