Azelaic Acid is a topical treatment, and it is actually a naturally occurring dicarboxylic acid. This means that it is already found in the skin. Your body already produces it, and it can be found in wheat, barley, and rye.
The majority of studies for azelaic acid were done at 20 percent, but you can only get it at 10% OTC so it’s not going to be as effective. This is why it’s good to use azaleic acid with other actives so they can work together in order to achieve potency. The stability of azelaic acid is best in a gel, and it works great with PHAs, BHAs (salicylic acid), and Vitamin C derivatives like sodium ascorbic acid. However, azelaic acid is Ph neutral (4 or 5 on the Ph scale) and ascorbic acid (pure vitamin C) has a Ph of 3. So, the combination of azelaic acid and vitamin C can be irritating if not used with caution. Azelaic acid also works well with retinaldhyde (one in the morning and one at night), green tea extract, niacinamide, and alpha arbutin. Alpha arbutin is a tyrosinase inhibitor so the two together are great for hyperpgimentation and acne.