Formulating with azelaic acid: solubility, pH and stability in practice

Azelaic acid rewards formulators who understand its physical chemistry. Its multifunctional profile makes it attractive for many product concepts, from serums for blemish prone skin to soothing creams and scalp treatments. This article summarizes the practical points our technical team discusses most often.

Working with limited water solubility

Azelaic acid has limited solubility in cold water. In practice this is rarely a problem, because most formulations do not require the active to be fully dissolved. A finely micronized grade such as Azepur99® disperses evenly and remains physically stable in emulsions and gels.

When a clear or fully solubilized system is required, solubility can be improved in several ways: by dissolving the active in the heated water phase, by using suitable solvents and solubilizers in the formulation, or by working with partially neutralized systems, since salts of azelaic acid show a higher water solubility.

Choosing the right pH

Azelaic acid performs well in the mildly acidic range that is typical for skin care products. The active itself is stable across a wide pH range, which gives formulators freedom to balance efficacy, sensory profile and preservation. As the pH rises and more of the acid is neutralized, solubility increases while the character of the formulation changes, so the target pH is best chosen early in development.

Stability and processing

Azelaic acid is thermally stable under normal processing conditions and does not require special handling beyond standard good manufacturing practice. It is compatible with a broad range of common cosmetic ingredients and can be combined with other actives to build multifunctional concepts.

Use levels

Typical use levels depend on the application. Lower concentrations are common in daily care and scalp products, while leave on treatments for blemish prone or uneven looking skin often use higher levels. The consistent purity and controlled particle size of Azepur99® support formulation work across this whole range.

Our team is happy to think along with your specific formulation. Contact us for technical support or browse the knowledge base for more detailed guidance.