Well, it totally depends upon the type of product you are using, the waiting time may vary. Any activity with a PH value less than 5.5 requires more waiting time. And similarly, for any actives with a pH value greater than 5.5, you can wash them away in 15 minutes. Again, if you experience any dryness or irritation after applying the actives, choosing a proper moisturizing agent to improve the hydration is the best option.