Regardless of the strength, Dr Sommerlad said it can be used in both morning and evening routines. "Unlike other ingredients, it can be used morning and evening," she said. "If using in the morning, apply after a vitamin C but before SPF." Nugawela added that if using in the evening, apply a thin layer on clean, dry skin at least half an hour before bed. "Be mindful that if using a prescription-strength retinoid as well, limit azelaic acid to alternate days or in the morning only," she said.
Although combining active ingredients can be a minefield, Travis said that azelaic acid plays well with other ingredients. "It's a great ally and I like pairing it with ingredients that have antiblemish and brightening properties," he explained. Dr. Sommerlad added that not only does azelaic acid work very well with a number of ingredients, particularly retinoids, antioxidants, and liquid exfoliants, it can also increase the potency of their effects. "It is a real skin-care hero of mine but as always, when using active ingredients, gradually introduce your skin to azelaic acid, by applying it only a few times a week for the first week or two before building up," she said.
