Use 004 in the morning and 003 on the evenings you use retinol. There is no need to layer both Ozera serums in one sitting.
Start with one change
Buying two serums does not mean opening them together. First decide which step you want to add. Learn its directions and give yourself time to notice how the finished product agrees with you before introducing the other.
If several products arrive on the same day, keep the unopened ones aside. It is easier to understand a routine when you can name the last thing that changed.
Give each its own time
004 belongs before cream in the morning. 003 belongs before cream at night, starting twice a week and following its directions. Wear daytime sunscreen as directed, including on days after an evening without retinol.
Different products need their own answer
This is an arrangement for our range, not a universal compatibility chart. Other formulas, prescription products and personal sensitivities change the question. Read their labels and ask your clinician if you are unsure about a combination.
Discomfort is a reason to stop and reassess. It is not a step toward making a routine work.
Photography: Dolunay laylay / Unsplash. Editorial photograph.