Researchers writing in JAMA Dermatology say that the evidence for light therapies as effective acne treatments remains weak and inconclusive.
Of the many varieties of light therapy that have been recommended for acne treatment — red, yellow, green, blue, blue-red, infrared, broad-spectrum light, intense pulsed light, aminolevulinic acid-PDT, pulsed-dye lasers, 1450-nm lasers or blue light–emitting diodes — one rises to the top: red-light methyl aminolevulinate-photodynamic therapy (MAL-PDT). In this JAMA review, “it was the only treatment associated with a small though clinically insignificant reduction in the number of inflamed lesions and in global improvement as assessed by an investigator in moderate to severe acne.” Furthermore, it was found to be associated with no more severe adverse effects than placebo or no treatment.
Still, safety for all light therapies remains a concern simply because there has been little reporting of adverse effects.
“There are many treatment options [for acne], but often with no clear best choice,” said author Josip Car, M.D., Ph.D., director of the Centre for Population Health Sciences at Nanyang Technological University in Singapore. “Light therapies are popular, yet evidence of their effectiveness and safety was unclear prior to our review, which looked at a plethora of interventions, such as red, green, yellow or blue light therapies.”
This review was originally published in the Cochrane library and included 71 studies from Brazil, Canada, China, Denmark, Egypt, Germany, Israel, Nigeria, Norway, Romania, Russia, South Korea, Sweden, Taiwan, Turkey, United Kingdom and the United States. It was based on data from 4,211 adult patients who were treated between 2000-2015.
The review consisted of more than 50 separate comparisons and a variety of outcome measures.
The three primary outcomes were participants’ global assessment of improvement, investigator-assessed changes in lesion count and investigator-assessed severe adverse events. The three secondary outcomes were investigator-assessed change in acne severity, investigators’ global assessment of improvement and changes in quality of life.
Red light topical methylaminolevulinate-photodynamic therapy (MAL-PDT) was the only treatment associated with improvements in outcomes in patients with moderate to severe acne. “But even that treatment failed to demonstrated clinically relevant improvements,” Dr. Car said.
For red light topical MAL-PDT versus control in improving investigator-assessed changes in moderate to severe acne vulgaris, various protocols were assessed.
For change in the number of inflamed lesions, there were two protocols: Four sessions of 80-mg/g topical MAL-PDT versus placebo cream plus red light at six weeks, and two sessions of 160-mg/g topical MAL-PDT versus no treatment at 12 weeks.
For investigator-assessed global improvement, there were also two protocols: Four sessions of 80-mg/g red light topical MAL-PDT versus placebo cream plus red light at six weeks, and four sessions of 40-mg/g red light topical MAL-PDT versus placebo cream plus red light at six weeks.
Investigator-assessed number of severe adverse effects was limited to one protocol: four sessions of 80-mg/g red light topical MAL-PDT versus placebo cream plus red light at six weeks.
“There was a small reduction in the number of inflamed lesions and in global improvement as assessed by an investigator. But there was no difference between the topical MAL-PDT and placebo in the number of severe adverse events,” Dr. Car said.
The one severe adverse event was an application site blister and scarring among 100 patients who were administered 80 mg/g red light topical MAL-PDT.
In summary, there just isn’t enough clinical evidence to warrant medical recommendations for light therapies.
“Due to limited evidence, we are currently unable to recommend any light therapies as a treatment option for people with moderate to severe acne. We also call for a review of guidelines. Until there are more studies with positive results, the use of light therapies cannot be recommended,” Dr. Carr said.
The authors suggest that more research is needed to identify the biological mechanisms of action of red light MAL-PDT and other light therapies.
Pawel Posadski, Josip Car. “Light Therapies for Acne.” JAMA Dermatology. Published online March 14, 2018. DOI:10.1001/jamadermatol.2018.0110