Retin-A (a brand name for tretinoin) is one of the most extensively researched anti-aging and anti-acne medicines on the market. It's really effective. However, tretinoin has a well-known adverse effect of skin irritation, which can leave you with red, irritated, and flaky skin. As a result, a good moisturizer is important, but which moisturizers work best with Retin-A/Tretinoin? Here's a summary of what to look for in a moisturizer when using Retin-A, as well as which moisturizers are ideal to use with Retin-A based on your skin type or problem.