Itch is defined as an unpleasant sensation that evokes the desire to scratch. Chronic itch, defined as itch persisting for more that 6 weeks, is a key symptom in many diseases severely affects the quality of life of the affected patients and represents a substantial economic burden for the society. At present, there are no effective treatments for chronic itch diseases. Moreover, chronic itch patients express differences in their genes compared with people who do not suffer from itch.

With this experiment, we wish to analyse differences in genes expression in healthy volunteers who have been exposed to artificial itch from small plant needles from the plant cowhage (mucuna pruriens) and compare them to controls who have not been exposed to itch.

The study takes place over 2 sessions over a period of 2 days. Thirty healthy participants will be randomly allocated into two groups named "active group", treated with active cowhage spicules, and "control group", exposed to inactivated cowhage spicules.

During the 1st session, the participant will fill out a questionnaire including basic information and after participants in the active group will be treated with cowhage spicules for 15 minutes, while participants in the control group will receive the inactivated cowhage spicules. All subjects will be provided with a visual analog scale in which they have to report continuously the sensation of itch and pain on a scale from 0 to 100 for 15 minutes. Before cowhage application, 30 minutes and 3 hours after cowhage application, blood samples will be collected from all participants. The 2nd session will take place 24 h after the 1st session and in this session the final blood sample will be collected.

Inclusion Criteria:

• Healthy men and women
• 18-60 years
• Speak and understand English

Exclusion Criteria:

• Pregnancy or lactation

• Drug addiction defined as any use of cannabis, opioids, or other addictive drugs

• Previous or current history of neurological (e.g., neuropathy), immunological (e.g., asthma, immune deficiencies, arthritis) musculoskeletal (e.g., muscular pain in the upper extremities), cardiac disorder, or mental illnesses that may affect the results,

• Lack of ability to cooperate

• Current use of medications that may affect the trial such as antihistamines, antipsychotics, and pain killers, as well as systemic or topical steroids

  • Allergy to lidocaine
  • Skin diseases (e.g., atopic dermatitis, pruritus nodularis, eczema, psoriasis)
  • Moles, scars, or tattoos in the area to be treated or tested.
  • Consumption of alcohol or painkillers 24 hours before the study days and between these
  • Smoking
  • Acute or chronic pain
  • Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)

The participants are blinded about receiving active or inactive cowhage