Three acne light therapies, no clear winner

Light and laser devices have become a routine part of dermatology because they are quick, reasonably predictable and have few side effects, and several different systems are promoted for inflammatory acne. Q-switched Nd:YAG at 1064 nm, pulsed dye laser, intense pulsed light, diode lasers and laser-based photodynamic therapy have all been studied. What patients and clinicians lack is a direct comparison telling them whether the choice of device changes the result. This trial set out to compare three of the most commonly offered options under the same protocol, and to look at both the lesions themselves and the impact acne has on daily life.

This pilot study was a three-arm randomised controlled trial in 36 patients with moderate to severe inflammatory acne. Participants were randomly allocated to receive three pulsed dye laser treatments, three intense pulsed light treatments, or three sessions of Q-switched Nd:YAG 1064 nm laser, in every case at two-week intervals. Outcomes were acne lesion counts and severity scores recorded at each treatment session, plus acne-related disability measured with the Cardiff Acne Disability Index from baseline to two weeks after the third session. Adverse effects and pain during treatment were also recorded.

There were no significant differences in lesion counts or severity scores between the three groups at any treatment session, with P-values ranging from 0.06 to 0.92. Within each group, however, lesion counts and severity fell significantly over the course of the study. Acne-related disability on the Cardiff Acne Disability Index also decreased significantly from baseline to two weeks after the third session in all groups, indicating improved quality of life, again with no significant difference between arms (P = 0.45). Adverse effects were minimal: one participant in the pulsed dye laser group reported mild erythema, and the Nd:YAG group reported less pain during treatment.

The finding that all three modalities improved lesions and quality of life is consistent with the broader literature supporting light-based approaches in acne, but the absence of any between-group separation complicates claims that one wavelength or device is superior. With a dozen or so patients per arm, this trial could only have detected large differences, so genuine but modest advantages cannot be ruled out. There was also no untreated arm, so how much of the improvement reflects the devices rather than time or co-interventions is unresolved, as is durability beyond two weeks after the final session.

For someone weighing up in-clinic light treatments for inflammatory acne, the honest reading is that this small trial gives no evidence that one of these three options beats the others on lesion counts or on how much acne interferes with life. Tolerability may be a more practical differentiator: the Nd:YAG arm reported less pain, and side effects overall were mild and uncommon. The improvement in Cardiff Acne Disability Index scores is a reminder that acne outcomes are not only about counting spots. Because follow-up ended shortly after the third session, nothing here speaks to how long any benefit lasts.