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Azelaic acid, also known as azelaic acid, has nothing to do with azaleas despite its name. It is a naturally occurring saturated dicarboxylic acid. The similarity between its English name (Azelaic acid) and azalea (Azalea) likely led to a mistranslation, which became its common name.

In medicine, many applications of azelaic acid have been discovered. Medical professionals observed that the skin of patients with tinea versicolor would partially lighten. But what caused this skin lightening? Further research revealed that the secretions of Malassezia furfur, which causes tinea versicolor, inhibit melanin production, , thus causing white patches in the affected areas. This secretion is azelaic acid.

In fact, azelaic acid has a 50-year history of application. It can be found in the secretions of some plants and microorganisms in nature, but the content is too low, so it mainly relies on chemical synthesis.

Azelaic acid (nonanedioic acid) only sounds similar to azalea (Azalea) in English, a mistranslation. Azaleic alcohol, however, is a component truly found in Rhododendron fauriae and is widely present in medicinal plants such as white birch, maple, cedar, and yew.

Azaleic alcohol gained attention after a "vitiligo incident" involving a major Japanese brand. Statistics show that among 800,000 people using cosmetics containing azaleic alcohol, 19,605 subjects (as of October 2016) claimed to have developed vitiligo, accounting for 2.0% to 2.5% of the total.

「 A Versatile Player in Skincare

Directly inhibits and kills bacteria on the skin surface and in hair follicles, eliminating pathogens;

Competitively inhibits the enzyme activity (5α-reductase) that catalyzes the production of dihydrotestosterone, reducing excess skin oil caused by dihydrotestosterone;

Inhibits the production of reactive oxygen species, which is beneficial for anti-inflammation;

Reduces the synthesis of filaggrin, preventing excessive keratinization of hair follicles;

Disrupts the mitochondrial respiration of abnormal melanocytes, inhibiting their DNA synthesis, thereby inhibiting the proliferation of abnormal melanocytes.

Note: Azelaic acid selectively acts on abnormal melanocytes (because AzA has high permeability to abnormal cells) and has no effect on normal melanocytes.

In the skincare industry, azelaic acid is often used in oil control and acne treatment, whitening and spot removal, and hair loss prevention products. Here are a few typical examples.

Acne Treatment, Oil Control, and Acne Removal

In the "Chinese Expert Consensus on the Diagnosis and Treatment of Rosacea," azelaic acid is the first-line treatment for persistent erythema and papulopustules on the face in rosacea, with a commonly used concentration of 15% to 20% gel. The US Food and Drug Administration has approved 15% gel and 15% foam for the treatment of adult rosacea and has established its efficacy.

Whitening and Spot Removal

Clinical trials have confirmed that 329 women with melasma used either 20% azelaic acid cream or 4% hydroquinone cream for 24 consecutive weeks. The results showed that 65% of patients in the azelaic acid cream group and 70% of patients in the hydroquinone cream group showed significant effects, and the azelaic acid cream group did not experience allergic reactions.

Auxiliary Hair Loss Prevention

According to literature, azelaic acid can reduce scalp oil secretion and has a certain activating effect on hair follicles. Many mature hair growth products abroad add 15% azelaic acid and 5% minoxidil.

Advantages: Azelaic Acid

Azelaic acid, as an acid, is not photosensitive and can be used during the day. Compared to salicylic acid and mandelic acid, even high concentrations of azelaic acid do not cause significant irritation, and its antibacterial effect far surpasses that of salicylic acid and mandelic acid; compared to antibiotics, azelaic acid does not have drug resistance and can be used long-term. For cosmetics, antibiotics are still prohibited substances.

Disadvantages: Azelaic Acid

Azelaic acid has poor compatibility, limiting its application: poor solubility, basically "insoluble in water and oil," with a solubility in water at room temperature of only 0.24%. When added at high concentrations, it easily precipitates, which is wasteful in a sense and results in poor application feel.