Azelaic acid is a naturally occurring dicarboxylic acid that is found in grain, and is also made on the human skin by the normal yeast commensals. Its function is similar to that of hydroquinone. It can inhibit the tyrosinase, but will not cause direct damage to the melanocytes.

Its effect can be enhanced if used together with tretinoin. It can lighten epidermal type of melasma, but not really effective against the dermal type. Clinical studies showed that it is as effective as 4% hydroquinone in this, with 65 - 70% improvement after using it for 24 weeks.

Azelaic acid can be used to treat mild to moderate acne because of its anti-bacterial property of inhibiting the bacteria (Propionibacterium acnes and Staphylococcal epidermidis) inside the follicle; as well as keratolytic property by normalising the disordered growth of the skin cell lining the follicle. It is also used as a topical treatment for Rosacea, due to its ability to reduce inflamation.

Azelaic acid may cause some mild skin irritation but rarely cause allergic reaction. The good thing about azelaic acid is that it will not cause Onchronois or local white patches.