The purpose of this study is to explore the safety, tolerability, and preliminary efficacy of ALA used with photodynamic therapy for the treatment of moderate to severe acne vulgaris.

Inclusion Criteria:

1. Chinese male or female patients aged 18 - 40 years;
2. Grade III-IV facial acne vulgaris according to the Pillsbury International Improvement scale.;
3. All patients claimed to take effective contraception from 14 days before to 1 month after the end of the study, (among those who had used contraceptive two weeks prior to the study, the dosage of the drug should remain the same throughout the study) and had no fertility or donation of sperm/egg plan;
4. Informed consents were signed.

Exclusion Criteria:

1. Suffering with malignant tumors, cardiac, endocrine, blood, liver, immunity, metabolism, urinary system, lungs, nervous system, rheumatism / joint, psychology and kidney diseases;
2. Obviously abnormal liver and kidney function;
3. Suffering with allergy diseases; suspected or known to have porphyria; allergic to studying drugs and / or porphyrin; allergic to visible light; allergic constitution (allergic to two or more drugs, food or pollen);
4. Secondary acne patients, such as occupational acne or acne caused by corticosteroids;
5. Complicated with other obvious facial skin diseases such as actinic dermatitis, psoriasis, seborrheic dermatitis, eczema, skin tumors, etc;
6. Other diseases that may significantly affect the efficacy evaluation;
7. Pregnancy, lactation patients;
8. Exposed to systemic retinoids 2 months prior to the study (acitretin for 6 months);
9. Exposed to systemic antibiotics, glucocorticoids, spironolactone and other drugs for treating acne 4 weeks prior to the study; physical therapy for the treatment of acne;
10. Exposed to topical retinoids on the face 4 weeks prior to the study or topical antibiotics, glucocorticoids, and other topical treatment 2 weeks prior to the study;
11. Participated in other clinical trials 3 months prior to the study;
12. Other reasons that the investigator considered inappropriate for participation in the study.