From Oliver Sorg, 2007:
Conclusion of study:
Conclusions These preliminary results indicate that IPL, although filtered for wavelengths shorter than 500 nm, can generate oxidative stress, a typical hallmark of UV-A, but does not induce thymine dimers. This emphasizes the need for long-term studies involving IPL before using this technique in a recurrent manner.
This elaborates on the above:
However, the level of lipid peroxides in IPL-exposed skin was six times as high as in nonirradiated skin and twice as high as in skin exposed to UVA light.
Comment: The implication of this study is that IPL treatment may not be without consequences. Although IPL irradiation did not affect thymine dimer production because the light source does not emit in the UV range, it did produce considerable amounts of lipid peroxides, an indicator of oxidative stress. Oxidative stress has been associated with a number of deleterious effects; beyond premature aging of the skin, it has been shown to promote skin cancer in experimental animal models. Although these molecular studies do not necessarily mean that long-term adverse effects will ensue, the results point to our ignorance of IPL’s lasting effects. Many highly effective therapies have had adverse effects that were not fully identified until years after regulatory approval. Until IPL has been in active use for a while longer, continuing follow-up of patients remains important.