Retin-A

Experts say tretinoin, the active ingredient in Retin-A and a derivative of vitamin A, is one of the few proven topical treatments for wrinkles. These prescription-strength ingredients communicate with skin cells to help them produce healthier cells and stimulate collagen production. Users say there is an adjustment period associated with Retin-A, during which skin may become dry, flaky and irritated, but most say that it will eventually pass.

You can get over-the-counter wrinkle creams that contain a gentler version of vitamin A, called retinol, but dermatologists say the results aren't even close to what you'll get with prescription Retin-A. The big downside is the harshness of Retin-A, and the fact that your skin will actually get worse before it gets better. And, of course, prescription treatments are expensive, requiring trips to the doctor plus the cost of the product. It's also important to note that although Retin-A can reduce the appearance of wrinkles, it cannot rival cosmetic medical procedures, such as Botox and face lifts. And reviewers say skin will revert back to its original appearance once Retin-A is discontinued. Because all retinoid products can cause sun sensitivity, experts say Retin-A should only be used at night. A highly recommended over-the-counter retinol formula is Neutrogena Healthy Skin Anti-Wrinkle Cream -- Night (*Est. $13 for 1.4 oz.), which contains a gentler (and less effective) form of vitamin A.

Skin-care expert Paula Begoun provides the most comprehensive information about Retin-A and retinoids in general at her website Beautypedia.com. We also found helpful explanations at About.com and ConsumerReports.org. User reviews at MakeupAlley.com are useful in evaluating comfort levels and overall satisfaction of consumers.