Table 1 Study inclusion and exclusion criteria

Inclusion criteria

 • Healthy subjects of any sex and age

 • Fitzpatrick skin types I, II, or III (non-Hispanic, Caucasian ethnicity)

 • Non-dominant proximal anterior forearm is wide enough to ensure reproducible placement of light-emitting diode-red light (LED-RL) phototherapy or mock therapy hand-held unit

 • Available and willing to attend all clinic visits

 • Able and willing to give informed consent

Exclusion criteria

 • Subjects with Fitzpatrick skin types IV, V, or VI (ethnic groups)

 • Subjects on any photosensitizing medications (e.g., lithium, phenothiazine antipsychotics, and tetracycline antibiotics)

 • Subjects with light-sensitive conditions

 • Subjects with diabetes mellitus

 • Subjects with a history of melanoma and non-melanoma skin cancer

 • Subjects with systemic lupus erythematous

 • Subjects with open wounds on the non-dominant proximal anterior forearm

 • Subjects with fibrotic skin disease or other skin conditions on the non-dominant proximal anterior forearm

 • Subjects with tattoos that cover the procedure site on the non-dominant proximal anterior forearm

 • Subjects who previously participated in the phase 1 study of LED-RL in human skin (ClinicalTrials.gov Identifier: NCT02630303)