Red light 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) of actinic keratosis (AKs) is very well tolerated with the 2-step irradiance protocol, according to a recent study. Researchers performed a retrospective chart review to assess the level of pain during AK treatment by red light PDT (n=99). Natural density filter was used to reduce the irradiance of the light source and initially 10 J/cm² dose was delivered at 35 mW/cm² and then, 65 J/cm² dose was delivered at 70 mW/cm². Pain level was measured using a 10-point visual analog scale at 3 points during the procedure. They found:

• Pain was low to moderate in most patients (mean ± standard error of the mean pain score: 2.35 ± 0.19).
• Higher pain was seen mid-procedure vs at the beginning and at the end of PDT.
• There was no significant difference in pain perception between genders and different treatment areas.