Traditional at-home light therapy, which must be performed daily with tabletop red and/or blue light, produces very few side effects but also tends to produce disappointing results. However, dermatologists are now using light therapy on patients in their offices in a different way with better results but with more pronounced side effects. The procedure is called photodynamic therapy (PDT). The first step is what makes PDT different from at-home light therapy. A photosensitizing agent is applied to the skin. This primes the skin to react to the light that is applied. Next, red and/or blue light is shone on the skin for 15-20 minutes. Due to the power of photosensitizing agents, the reaction with the light creates more side effects and can include severe pain during the procedure and a full week of downtime afterward. The entire procedure is repeated 3-5 times at 2-4 week intervals, and is normally reserved for moderate to severe acne.
Results tend to be far better and longer lasting than light therapy alone when the procedure is done correctly. What is “correct” is up for debate, but science is pointing us more toward red light, which penetrates the skin more deeply. Other considerations are also important. Check out the new Photodynamic Therapy (PDT) page of acne.org for the full story on this new therapy.