Work up to it!
Always patch test before applying to your entire face! Start by applying the azelaic acid 20% product in the evening to a small area on your forehead (where your facial skin is thickest). If there’s no irritation within 24 hours, apply a thin layer of product to your entire face every evening. If there’s no irritation after a week and you want to get more aggressive with the treatment, begin applying the product both morning and night.
FYI: slight tingling and/or redness are both totally normal when applying azelaic acid.
Apply to entire face
Azelaic acid works best when applied to your entire face (avoid eyes, lips, and mouth) because it removes dead skin cells from your pores and fights to prevent acne bacteria from growing. This helps prevent future breakouts...and obviously you want to prevent that.