#$%^&*AU2019200152A120200227.pdf#####ABSTRACT A method of enhancing penetration of a topical composition of 5-aminolevulinic acid (ALA) into tissue for photodynamic therapy includes topically applying ALA to a treatment area to be treated with photodynamic therapy. The method further includes, after the ALA is applied to the treatment area, covering the treatment area with a low-density polyethylene barrier. The treatment area is covered with the low-density polyethylene barrier prior to light treatment to minimize transepidermal water loss from the treatment area. 10988386_1 (GHMatters) P110419.AU3/12 85 86 100 82 0G c8 87 84 cFIG. 3