The major signs of sun-damaged skin are that the outer layer of skin becomes thickened, wrinkled, and brown in patches. To some extent that does serve as protection, but it isn’t very good protection (it barely rates an SPF 2 or 4), nor is it very attractive! Both AHAs and BHA can help remove some of that thickened, wrinkled exterior—AHAs and BHA because they exfoliate the built-up damaged surface layer of skin, and tretinoin or products containing it because they change abnormal cell production back to some level of normalcy. That change to the exterior of the skin does leave it more vulnerable to the effects of sun exposure. Yet it is far better to improve the appearance of damaged skin by removing that layer than it is to leave it in place for inadequate and unattractive sun protection. After all, it isn’t the AHAs or the tretinoin that cause the skin to be more sensitive to sunlight. All they do is remove the old, sun-damaged skin, allowing healthier “younger” skin to be on the surface. Sunscreen is always important, always, but it becomes even more essential to protect the fresh skin cells you are revealing if you are using AHAs or tretinoin on a regular basis.