Photodynamic therapy for acne vulgaris: A critical review from basics to clinical practice Part I. Acne vulgaris: When and why consider photodynamic therapy?

The first-line treatments for acne vulgaris are conventional topical and/or oral medications. However, many patients have contraindications, only partial response, significant adverse effects, or recurrence. Light-based treatments and photodynamic therapy (PDT) using topical precursors of porphyrins are off-label alternative treatments for acne vulgaris, with their own advantages and disadvantages. To date, there is no consensus on PDT methodology and parameters. An understanding of pathophysiology of acne, light-tissue interactions, and PDT mechanisms of action is helpful whenever PDT is considered as an alternative treatment. In general, blue light alone improves acne because of its antiinflammatory effects. PDT using 5-aminolevulenic acid (ALA) or ALA derivatives induces transient antimicrobial and antiinflammatory effects. At high doses, red light PDT may induce inhibition or destruction of sebaceous glands, resulting in clinical improvement. After completing this learning activity, participants should be able to compare different treatments of acne, recognize when photodynamic therapy may be a useful off-label treatment for acne vulgaris, and identify variables that may affect the efficacy of photodynamic therapy.