Skin serum: What it can and can’t do

• By Kelly Bilodeau, Executive Editor, Harvard Women's Health Watch

Many things improve with age; unfortunately, your skin is not one of them. Wrinkles, brown spots, and general dullness often start to creep in as the years tick by. To reverse these problems many women are turning to a skin serum. Serums are light, easily absorbed oil- or water-based liquids that you spread on your skin. They typically come in small bottles with a dropper, and you only need a few drops to treat your whole face.

A skin serum is not a moisturizer, like a lotion or cream, says Dr. Abigail Waldman, instructor of dermatology at Harvard Medical School. Rather, they are highly concentrated formulations that are designed to sink into the skin quickly, delivering an intensive dose of ingredients that can address common skin complaints. “I definitely recommend serums for anyone who is concerned about aging. It’s a really good way to get extra anti-aging effects, more than your typical moisturizer and sunscreen,” says Dr. Waldman.

How do you choose and use a skin serum?

Serums are typically applied to skin after cleansing but before moisturizing, says Dr. Maryam M. Asgari, associate professor in the department of dermatology at Harvard Medical School. Some serums have one main ingredient, while others, including those that target the signs of aging, are combination formulas. “I use and recommend serums that have a combination of vitamin C, vitamin E, and ferulic acid,” says Dr. Waldman. “There is good literature that shows that vitamin C in particular can prevent brown spots, reverse damage from ultraviolet rays, and stimulate the growth of new collagen.”

Other good skin serum options to target wrinkles are those with antioxidants including tea polyphenols and resveratrol. Retinol, which reduces inflammation, is another good option, as is niacinamide.

If you are looking to fight blotchiness and discoloration, look for formulas that can brighten and lighten dark patches, including kojic acid and glycolic acid. If your skin is dry, tight, and flaky, find a skin serum that contains vitamin E, niacinamide, and glycolic acid. Also look for ceramides, which are fatty molecules that help hold the skin together and keep moisture from escaping. Other good options are serums that contain hyaluronic acid, or those with collagen peptides, epidermal growth factors, or stem cells.

Are all skin serums created equal?

Not all serums work the same. How well they work depends on the active ingredients, the formulation, the vehicle, and the stability of the compound, says Dr. Asgari. The prices of serums vary from less than $20 to hundreds of dollars. “To be honest, I don’t think price makes a difference,” says Dr. Waldman. More important than price are the ingredients in the serum — so the best practice is to read labels to find the best formulation for your needs.

Caveats when using a skin serum

“Powerful ingredients can irritate sensitive skin,” says Dr. Asgari. “Always test a small area before you apply a skin serum widely.” And use caution when combining acid-containing serums with other products that also contain acids. For example, your skin may get irritated if you use a serum with vitamin C (which is acidic) and as well as a retinol cream, or if you use a retinol serum along with a prescription retinol cream.