Itch Sensation Induced by Simultaneous Application of Pruritogens (Spatial Summation)

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 * 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 * Acute or chronic pain * Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)