Even women who are the same age may have different skin needs. This is particularly true when you hit your 40s, since many problems that pop up during this decade hinge on what you did in your 20s and 30s.
"If you wore sunscreen, if you did some preventive care, then you may not notice any major difference in your skin," says Fox. "If you didn't do those things, then fine lines and wrinkles are definitely on the upswing once you hit 40."
The problem is a breakdown of collagen, natural fibers that form an invisible network of support underneath the skin and help it stay plump and firm.
As collagen stores begin to break down -- a process that is accelerated by sun exposure -- skin loses its moist, dewy look. In its place is drier, more fragile skin, with fine lines and small wrinkles appearing around the eyes and in the nose-to-mouth area.
Further, as the years pass, we shed old skin less frequently. That means your complexion looks not only drier, but also more dull and uneven.
Solutions, says experts, include products aimed at helping to increase cell turnover, like alpha-hydroxy acids and wrinkle-fighting ingredients like retinol.
"The 40s is definitely the time to start using a retinol product," says Antell. "The professional versions are the strongest so you're going to see the most dramatic results, but even some over-the-counter solutions can work well."
Retinoids work by helping to stimulate collagen production, so fine lines and wrinkles are less noticeable, he says.
Fox says home peels are also appropriate for 40-plus skin. They can help remove dead skin cells and encourage new cells to come to the surface.
Depending on how quickly your skin is aging, Fox says, don't be afraid to look toward professional treatments to help increase your window of youth.
"This is the decade when you should seriously consider some of the less aggressive but very helpful dermatologic procedures such as Thermage (a radio frequency treatment) or Fraxel (a laser) to tighten the skin and/or stimulate collagen production," says Fox.
Additionally, many women in their 40s experience hormone-related skin problems, including adult acne. But, Fox says, don't borrow your teenage daughter's acne products until you consult a dermatologist and a gynecologist. "Adult-onset acne can sometimes be the result of a gynecological problem like an ovarian cyst, so that should always be ruled out first," says Fox.
Next, he says, check with a dermatologist about whether your "pimples" are really acne.
"Many women confuse acne with rosacea, another skin problem that can occur in the 40s and 50s," says Fox.
While the breakouts can look similar, Fox says, they may require different treatment.
Makeup tips: Toss away your cakey face powder, Fazio says.
"This is the decade when skin is really dry, and most powders will dry it further and accentuate fine lines and wrinkles," she says.
If you must use powder to tame oily areas, choose one that is finely milled, and apply it sparingly, using a brush instead of a puff.