Azelaic acid is a naturally occurring dicarboxylic acid found in wheat, rye, and barley (and produced by the yeast Malassezia that normally lives on skin). In skincare, it is unique in being effective for three distinct concerns simultaneously: acne (by killing P. acnes bacteria and reducing inflammation), hyperpigmentation (by inhibiting the enzyme tyrosinase, which drives melanin production), and rosacea (through anti-inflammatory mechanisms). It is available OTC at 10–15% and by prescription at 20%, is pregnancy-safe, causes no photosensitivity, and is one of the most underused ingredients in skincare.
Azelaic acid is a proven antibacterial agent against Propionibacterium acnes (now reclassified as Cutibacterium acnes) — the bacteria implicated in inflammatory acne. A 20% azelaic acid cream has shown comparable efficacy to 0.05% tretinoin and 2% erythromycin in clinical trials. Crucially, unlike antibiotic treatments, P. acnes does not develop resistance to azelaic acid. It also normalises the abnormal keratinisation inside pores that contributes to comedone formation.
Azelaic acid inhibits tyrosinase — the rate-limiting enzyme in melanin synthesis — with a selectivity for abnormally active melanocytes (the overactive pigment cells that cause dark spots). Crucially, it does not depigment normal skin, only the hyperactive melanocytes responsible for post-inflammatory hyperpigmentation (PIH), melasma, and UV-induced dark spots. This selectivity makes it safer for prolonged use than hydroquinone, which can affect all melanocytes equally and may cause rebound hyperpigmentation with long-term use.
The FDA has approved prescription 15% azelaic acid gel for the treatment of inflammatory rosacea. Its mechanism involves suppression of reactive oxygen species and pro-inflammatory cytokines in the skin, as well as a reduction in the abnormal skin flora changes associated with rosacea flares. Over-the-counter 10% concentrations provide meaningful benefit for milder rosacea and general redness.
10% (OTC): Effective for mild to moderate PIH, general redness, very mild rosacea, and comedonal acne. A good starting point for most people.
15–20% (prescription in some markets, OTC in others): The clinically validated concentration for inflammatory rosacea and melasma. Paula's Choice 10% Azelaic Acid Booster is formulated as a concentrated treatment at the OTC limit — effective but not as potent as prescription-strength formulations.
20% (prescription): The strongest OTC/Rx formulation, generally reserved for melasma, significant rosacea, or recalcitrant PIH under medical supervision.
Apply to clean skin as a serum or treatment, AM or PM (or both). It tolerates combination with niacinamide (both address pigmentation and inflammation by complementary pathways), hyaluronic acid, and SPF. Avoid combining with high-percentage AHAs or BHAs in the same step — apply acids first and allow them to absorb, then apply azelaic acid.
Initial stinging or tingling is normal. If it persists beyond the first two weeks, reduce frequency or patch test to rule out a sensitivity reaction.
Azelaic acid is one of the most underrated ingredients in mainstream skincare. Its multi-pathway action — antibacterial, anti-inflammatory, melanin-inhibiting — makes it uniquely valuable for anyone dealing with acne, post-acne marks, rosacea, or melasma. Its safety profile means it can be used daily, morning and evening, without restrictions, and it is among a very small number of effective actives considered safe in pregnancy. If it is not in your routine, it probably should be.