The aim of this study is to explore the effect of medical LEDs (830 nm and 590 nm) in the prevention and treatment of PIE and PIH.

Evidence regarding the efficacy of LEDs for post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH) is limited.

The aim of this study was to evaluate the efficacy of 830 nm and 590 nm LED phototherapies on PIE and PIH.

Design of the study:

308 nm LED light (1.5 MED) induced an in vivo PIE/PIH model on the thigh of ten healthy subjects. 830 nm (60 J/cm2) and 590 nm LED (20 J/cm2) were irradiated respectively. For therapeutic irradiation, PIE/PIH model was induced on D1, and LEDs were irradiated on D0, 1, 3, 6 and 8. For preventive irradiation, LEDs were irradiated on D0, 1, 3, 6 and 8 and PIE/PIH model was induced on D9. Erythema index (EI), melanin index (MI), transdermal water loss (TEWL) and C-Cube photography were measured during 10-day follow-up visits.

Inclusion Criteria:

1. Healthy Asians;
2. 20-65 years old;
3. Fitzpatrick classification III-IV;
4. Sign the informed consent form.

Exclusion Criteria:

1. Have abnormal skin manifestations, such as pigment diseases, photosensitivity diseases and other allergic diseases;
2. Those with a history of abnormal systemic diseases, such as heart disease, liver disease, kidney disease, tumors, and mental illness;
3. Women who are preparing for pregnancy, pregnant or breastfeeding;
4. Have used photosensitizing drugs within two weeks before inclusion in this study;
5. Topical or systemic drugs may be used during this study;
6. bad habits, such as smoking, drinking, etc.;
7. Volunteers who have recently participated in other clinical trials;