Displaying 3 results of Azelaic Acid Impurities Azelaic acid is a medication used to treat acne, rosacea, and hyperpigmentation. However, like all chemicals, it can contain impurities that may be harmful to the user. These impurities may include residual solvents used during manufacturing, byproducts of the chemical reaction, and other contaminants. It is important to ensure that the azelaic acid used in medications is free from harmful impurities to ensure the safety and efficacy of the product.