Perioral Dermatitis Triggers and Prescription Treatment
Identify the triggers and prescription strategies that stop this chronic facial rash.
Dr. Marcus Lien
Clinical Science Editor
Dr. Marcus Lien
A former dermatology resident who left clinical practice to translate medical research for general audiences, Marcus Lien has been writing about skin medicine and emerging clinical technology since 2009. His work bridges peer-reviewed findings and practical patient guidance, with a sharp eye for overhyped ingredients and understudied conditions.
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Skincare Products That Cause Acne Breakouts
These products clog pores and trigger breakouts you won't connect to them.
Dr. Marcus Lien
Acne Vulgaris vs Fungal Acne Differences
Misdiagnosis turns acne antibiotics into fungal yeast fertilizer.
Dr. Marcus Lien
Hyaluronic Acid Molecular Weight and Skin Penetration
Smaller hyaluronic acid molecules penetrate skin while larger ones hydrate the surface.
Dr. Marcus Lien
Salicylic Acid vs Glycolic Acid for Acne-Prone Skin
Salicylic acid treats clogs; glycolic acid treats what's left behind.
Dr. Marcus Lien
Rosacea Subtypes and Evidence-Based Treatments
Matching treatments to rosacea's four subtypes improves outcomes for millions misdiagnosed annually.
Dr. Marcus Lien
Azelaic Acid Clinical Uses for Acne and Hyperpigmentation
This saturated dicarboxylic acid treats acne, fades dark spots, and works safely in pregnancy.
Dr. Marcus Lien
Eczema vs Psoriasis vs Fungal Rash Visual Differences
Learn the visual markers that separate these three look-alike rashes.
Dr. Marcus Lien