Use every day, as many times as needed. For most people, it's best to use a moisturizer twice per day. In the morning, apply it before your sunscreen (or skip the moisturizer in the morning if your sunscreen feels hydrating enough). In the evening, a moisturizer is usually the last step of a routine.

Use your azelaic acid product every other day, either in the morning before your sunscreen or at night, before your moisturizer.

Start slowly with this product: it can be irritating, but your skin can adjust to it with time. It is best to start using this product only once a week for the first few weeks. Mild dryness is normal when starting using a retinoid. Once your skin is able to tolerate the product well, you can increase the frequency of use to twice, and even three times a week. Make sure to apply a moisturizer regularly when using this product. Apply this product on clean skin, before a moisturizer. Most people prefer using this product at night, but it can be used in the morning as well.