Retin-A

Bottom line

Retin-A is a prescription-strength formula that relies on retinoid to reduce the appearance of fine lines and wrinkles. It's available in cream, gel or liquid textures and in four different strengths: 0.01, 0.025, 0.05 and 0.1 percent. The formula is strong and effective, but likely to cause irritation, which experts say usually fades with continued use. If you prefer a gentler form of vitamin A, Neutrogena Healthy Skin Anti-Wrinkle Cream -- Night (*Est. $13 for 1.4 oz.) is a popular over-the-counter option.

Performance

Proven effective: 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. Julyne Derrick, beauty guide for About.com, swears by Retin-A as the best beauty secret for reducing fine lines and wrinkles. 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 can be 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. In addition, all retinoid products can cause sun sensitivity; experts say Retin-A should only be used at night.

Feel and smell

Likely to cause irritation: Several users say that Retin-A smoothes out the texture of their skin, making makeup easier to apply or unnecessary altogether. At the same time, we saw lots of comments about skin irritation, including flaking, redness and itchiness, but most maintain that these issues go away within a couple of weeks. Experts recommend using a good, gentle moisturizer to help alleviate irritated skin. For product recommendations, see our report on facial moisturizers.