Intense pulsed light (IPL) is a conventional treatment for hair removal. Even though the side effects after IPL are recognized, the risk factors have to be investigated. The main aim of this study was to evaluate the involvement of skin pigmentation, ultraviolet radiation (UVR) and fluence level on IPL-induced side effects.

A randomized intra-individual, blinded and controlled trial was conducted that includes 16 healthy participants with Fitzpatrick Skin Types (FST) II-V. The test areas were divided into four sites and randomized to a single IPL exposure of 22, 34, 46 J/cm2 or triple stacking of 46 J/cm2. The test areas were randomly assigned to single solar-simulated UVR or no UVR exposure. They were randomized to three Standard Erythema Dose at 30 minutes or 24 hours after IPL. Each of the test areas had anequivalent control, which resulted in 15 treatment sites. Follow-up visits were organised up to 4 weeks after IPL. The results were measured as blinded clinical skin reactions, pain measured by visual analog scale (VAS), demonstrably measured erythema and pigmentation, histology and mRNA-expression of p53.

The results of the study showed that 15participants with FST II-IV completed the protocol. IPL made a varied range of skin reactions that included erythema (87% of participants), purpura (27% of participants), blisters (20% of participants), edema (13% of participants), crusting (13% of participants), hyper- (60% of participants) and hypopigmentation (20% of participants).

Increased IPL fluence level and darker skin pigmentation were factors for IPL-induced side effects, whereas a single exposure of UVR did not aggravate side effects. Clinical findings that were confirmed demonstrably by reflectance spectrometry along with histological changes in skin architecture, pigmentation and inflammatory infiltration. Marker of cellular DNA damagep53, did not increase after IPL.

The study concluded that skin pigmentation and IPL fluence are major factors of side effects after IPL exposure. A single exposure to three SEDs of UVR after IPL at 30 minutes or 24 hours does not increase the side effects.

Source: Thaysen-Petersen D, Erlendsson AM, Nash JF, et al. Side effects from intense pulsed light: Importance of skin pigmentation, fluence level and ultraviolet radiation-A randomized controlled trial. Lasers Surg Med. 2017 Jan;49(1):88-96. doi: 10.1002/lsm.22566. Epub 2016 Jul 30.