Azelaic acid

Azelaic acid is a naturally occurring dicarboxylic acid produced by Malassezia yeasts on skin. It has an unusually broad mechanism: mildly keratolytic, antimicrobial against C. acnes, anti-inflammatory via reactive oxygen species scavenging, and a reversible tyrosinase inhibitor[1].

The evidence

Two phase III trials of 15 % gel showed clear reductions in inflammatory lesions and erythema in papulopustular rosacea[2]. For melasma, 20 % cream performed comparably to 4 % hydroquinone over 24 weeks[3].

Cosmetic vs medicinal

The 15–20 % products with that evidence are drugs. Cosmetic versions sit around 10 %, where data are thinner and mostly extrapolated. It pairs naturally with niacinamideNiacinamideStrongNiacinamide · Vitamin B3 amideWater-soluble B3 with strong evidence for barrier, tone and sebum; among the most studied topical actives.Open in the Index → and tranexamic acidTranexamic acidModerateTranexamic Acid · Synthetic lysine analogueAntifibrinolytic drug repurposed for melasma; topical trials are small but consistent.Open in the Index → for pigment.