Adverse reactions following 5-aminolaevulinic acid photodynamic therapy (ALA-PDT) are detailed in study findings published in Photodiagnosis and Photodynamic Therapy. In addition to itching and hyperpigmentation, an inverse relationship was seen between increasing patient age and decreasing severity of adverse reactions. A positive relationship was found between the efficacy of ALA-PDT and the severity of adverse reactions, with light-to-moderate adverse reactions considered normal and perhaps a predictor of good efficacy.

ALA-PDT is a common treatment for moderate to severe acne vulgaris and adverse reactions are known. However, the lack of clinical detail regarding many of these adverse reactions may cause patient anxiety and interfere with efficacy; this prompted researchers to perform a systematic investigation for clarity and detail of adverse reactions for ALA-PDT in patients with acne vulgaris.

Investigators in China conducted a prospective study at the Shanghai Skin Disease Hospital that included 35 individuals (mean age, 23.5 years, range 18-31 years; 40% women) diagnosed with moderate to severe acne. The patients underwent treatment once a week for 4 weeks in which lesions were coated with 5% ALA for 90 minutes, then wiped before exposure to red light.

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Reactions were examined in acute-phase and recovery-phase. Acute-phase adverse reactions included erythema (94.3%), post-treatment pain (91.4%), burning skin (91.4%), dry skin (91.4%), itching (85.7%), and pustule (82.9%). Edema and blistering were noted in 20% or fewer instances. Crust (65.6%), exudation (48.6%) and hyperpigmentation (42.7%) were seen in the recovery-phase. Men indicated itching more often than women, and pustules were more common among younger patients. A positive relationship was noted between the severity of acute-phase adverse reactions and the efficacy of ALA-PDT for severe acne.

Researchers recorded, “the relative incidence of various adverse reactions following ALA-PDT for acne vulgaris.” Severity of adverse reactions decreased with increased patient age, but not for hyperpigmentation or itching. They added that, “Light-to-moderate adverse reactions might be the inflammatory reactions of ALA-PDT, predicting a good efficacy.” Based upon this research, investigators also designed a form to help clinicians manage adverse patient reactions.


Shi L, Yang J, Zhang L, et al. A prospective study of adverse reactions of ALA-PDT for acne vulgaris. Photodiagnosis Photodyn Ther. June, 2022;38:102752. doi:10.1016/j.pdpdt.2022.102752