To understand, prevent and treat the adverse reactions more comprehensively, we sought to systemically document the adverse effects of ALA-PDT for moderate to severe acne vulgaris.

To understand, prevent and treat the adverse reactions more comprehensively, we sought to systemically document the adverse effects of ALA-PDT for moderate to severe acne vulgaris.

Inclusion Criteria:

• (1) Patients diagnosed with moderate to severe acne and graded grade III-IV according to Investigator's Global Assessment (IGA) ;
• (2) Patients unsuitable for drug treatment owing to various reasons and who voluntarily participated and signed informed consent following information about other alternatives;
• (3) Patients who read the instructions and were willing to follow the program requirements.

Exclusion Criteria:

• (1) Patients who had a history of photosensitive diseases;
• (2) Patients who had Modified-PDT;
• (3) Patients who had oral isotretinoin in the past 3 months, used oral contraceptives or antibiotics and underwent local or facial surgery in the past 4 weeks;
• (4) Female patients who were pregnant or lactating.

Evaluator assesses photographs without prior knowledge of intervention