It is not recommended that people use both Salicylic and Lactic peels on the same day especially for first time users. Lactic is the stronger peel so combination of use of any other peels with the Lactic is strongly discouraged. We recommend to use the Salicylic peel, then wait 3 days before applying the Lactic. Once your skin becomes accustomed, you may move the application days closer, and then eventually apply on the same day but still do this with caution. The Salicylic Acid is very effective at removing dead skin cells, allowing the Lactic Acid to penetrate deeper into the skin, giving you a deeper peel. Remember that the depth of the peel is controlled by contact time, frequency of application, and thickness of application. After your peel, if you are experiencing what looks and feels like a sunburn, or if you experience discomfort in the days following an application, then the peel has penetrated too deeply. I recommend you wait at least 10 days before applying the peel again. This allows the time needed for new skin growth. Upon applying the peel to your skin again, you should reduce the application time. As your skin becomes accustomed to the treatment you may increase application time and/or thickness of the application as you are comfortable.