We let you choose the level that best describes where the status and age of your skin is now and also your skin treatment goals.  Then through a personalized treatment plan, we help you get there. Read more about our three levels and what they entail, or watch Dr. Young explain each one for you below. For each product (Rapamycin or Retin A) that you receive, you will apply starting with a tiny drop of each product mixed with a gentle moisturizer like Cetaphil Gentle Lotion. lf you don’t have reactions to this after 3 days then you can reapply the same product or introduce the next one and wait another 3 days for the next product. You can keep doing this process and eventually increase slowly by shortening the number of days you wait. Eventually, you will find the best frequency that you can tolerate with each strength of product that you are currently using. If at any time you have redness or irritation I would back off and increase the number of days that you wait for the next application. Level 1 stays at the introductory level of Rapamycin. Level 2 stays at the introductory levels of Rapamycin and Retin A. Level 3 starts with the introductory levels of both Rapamycin and Retin A and will increase the strength of both products based on your toleration.