Tretinoin cream is used for skin rejuvenation. The gel is too drying for mature skin unless it is very oily. Continue with the .05% cream, you do not need to have continued irritation for it to be effective. Studies have shown that the .1% cream will not offer any...
The generic version of Retin-A (tretinoin) is the best value. Tretinoin comes in three concentrations; 0.025%, 0.05%, and 0.1%. A 45g tube of 0.025% is approximately $60, the 0.05% is approximately $75, and the 0.1% is approximately $100. I usually start people with 0.025% as it causes less...
That is an outstanding question and one that I have wondered about myself.
I don't know if there is an answer.
I have pondered if we should limit the use on retinoids based on the Hayflick's ceiling on cellular division but I am not sure where I could find a reference.