Vitamin C is a popular ingredient in anti-wrinkle serums for all the same reasons that your body loves it. It's an antioxidant, which helps it defend our skin against free radicals that attack proteins and DNA and ultimately leads to a breakdown in collagen. It also helps protect our skin from UV rays that can cause freckles, brown spots and discoloration on delicate facial skin. The only thing you have to watch out for with vitamin C is skin sensitivity. Serums tend to contain active ingredients in high concentrations, which is why they're so effective. But this also creates the possibility of an adverse reaction. With any new product, it's always a good idea to do a patch test on a small part of your face before slathering it all over.
Another thing to watch out for with vitamin C-based anti-wrinkle serums is that the active vitamin C is microencapsulated, or in an otherwise stabilized form. Because vitamin C is naturally occurring, it's not the most stable ingredient, which means it doesn't have a substantial shelf-life. If it's not properly preserved in a formulation, it's highly likely that it will quickly lose its effectiveness. Some manufacturers package their serums in amber glass bottles to help protect the ingredients from light -- which also decreases the time it takes certain ingredients to break down -- but once the bottle is opened and exposed to air, the ingredients can still become unstable. So if vitamin C is your anti-aging ingredient of choice, just look for brands that boast microencapsulation technology.