I like to keep an eye on AHAs because they are pretty powerful - and therefore should be regarded with caution - and are the prime ingredient in a serum that I use, by Image Skincare.

The FDA has been investigating AHAs and, in particular the use of glycolic acid in cosmetics and treatments since 1997. Its main concern has been whether AHAs increase the skin's sensitivity to sun and that consequently - oh, irony of ironies - they actually speed up premature aging.

Human clinical studies found that topical application of glycolic acid at concentrations as low as 4% and for a duration as low as four days can increase sensitivity to UV radiation. The studies also found that sensitivity to sun is no longer evident after one week of discontinuing use of a glycolic product.

A warning notice is recommended by the FDA for manufacturers to include on product labeling to the effect that the danger of sunburn is increased and the product should be followed by application of a sunscreen. I can't say that I've seen this widely applied.

This all seeems to reinforce that daily use of a sunscreen or moisturizer containing a sunscreen is always a good idea. I use Murad's Perfecting Day Cream with SFP30.