How retinol cosmetics change your skin on a chemical level

How retinol cosmetics change your skin on a chemical level

Lori Youmshajekian

With so many different skin care products on the market, and how varied and varied they are, it can be hard to know if the various compounds and other chemicals in a product really do what they claim to do on the label. But from a scientific standpoint, there’s one ingredient that stands out above the rest: retinol. Decades of research have shown that retinol has great benefits for the skin, especially when it comes to treating acne and signs of aging. So what exactly makes retinol so effective?

Retinol is a retinoid, a general term for a group of compounds derived from vitamin A. Retinol first gained popularity in the 1970s when retinoic acid (the active form of vitamin A, also known as the topical prescription drug tretinoin) was used to treat acne. The retinol family includes adapalene, retinaldehyde, retinyl esters, and of course retinol itself, all of which are available over the counter. Retinoids are commonly referred to as “retinol,” but there are some important differences between them.

The difference between them is their potency, determined by how many steps it takes to convert them into retinoic acid. This compound binds to receptors in the nucleus of skin cells, instantly triggering a series of cellular changes that promote skin health. Retinoic acid stimulates rapid cell turnover, helping to slough off dead skin cells, but it can also cause unwanted side effects, like dryness and peeling. Most over-the-counter retinoid products contain what are called precursor molecules that need to be converted into retinoic acid to exert their biological effects. Retinyl esters, the least potent of the retinoids, are a gentler option because they need to go through three enzymatic steps before they become active, but they haven’t been studied as much as other compounds in this family, explains Patricia K. Faris, clinical associate professor of dermatology at Tulane University School of Medicine. Retinol goes through one less step, converting to retinaldehyde, which is then converted into retinoic acid.

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Most dermatologists estimate that retinol is about 10 times more potent than tretinoin. That means that when retinol undergoes the conversion process, only about 10 percent of it becomes retinoic acid. (In most tretinoin products, the active ingredient is usually at a concentration of 0.025 to 0.1 percent.) That’s why over-the-counter products contain high concentrations of retinol, says Faris. “You want to get the product ‘deep’ into your skin,” she explains, because only a small portion of the retinol gets converted by enzymes.

When applied, retinoic acid works to combat signs of aging on the skin. As people age, exposure to sunlight and pollution, combined with life factors like stress and lack of sleep, creates free radicals, Faris says. Free radicals are highly reactive molecules that can damage skin cells. When the skin can’t neutralize these free radicals with antioxidants, it experiences oxidative stress. This stress increases production of enzymes called matrix metalloproteinases (MMPs), which break down collagen and other types of “cement” that hold skin cells together, says Zakia Rahman, M.D., clinical professor of dermatology at the Stanford University School of Medicine.

When retinoic acid binds to the receptor, it increases collagen production and decreases MMP activity. Retinoic acid also promotes the production of elastin, a protein that gives skin its elasticity. Additionally, it stimulates the production of glycosaminoglycans (such as hyaluronic acid) that give skin its moisture and firmness. Retinoids thicken the epidermis, the outermost layer of skin, which makes skin smoother and reduces the appearance of wrinkles. Retinoic acid also increases cell turnover, helping to remove old, dead skin cells more quickly, reducing dark spots and pigmentation and revealing new skin. The compound also works on oil-producing skin cells to reduce sebum production. This works because sebum and dead skin cells can clog pores, creating a moist environment where bacteria can thrive. When these bacteria gorge on the sebum, it triggers an inflammatory response in the skin, which leads to acne. “Retinoids don’t just make your skin look better, they actually make it work better,” says Rahman.

But when it comes to these medications, stronger doesn’t necessarily mean more effective. One study compared three commonly prescribed strengths of tretinoin., The researchers applied each to one side of the subjects’ faces and found no significant differences in results. Both tretinoin and retinol treatments helped with sun damage, fine lines, wrinkles, pigmentation, and pore size. Retinol is marketed as a “cosmeceutical” and is usually thought of as having only cosmetic benefits. But, says Rahman, “that doesn’t mean it doesn’t have biological effects.” However, with these products, “it takes a little while to show up.”

Retinoids can also cause side effects. Oral isotretinoin, a potent derivative of vitamin A used for severe acne, is known to cause birth defects when taken during pregnancy. Topical retinoids are generally considered safe, but dermatologists still don’t recommend them for pregnant people. With prescription retinoids, retinoid dermatitis, characterized by “purging” of the skin, or redness, peeling, and inflammation, is common. That’s why over-the-counter retinoids are a good place to start. However, some people may still experience side effects. Retinoic dermatitis is usually a temporary side effect, but if it appears, it’s important to consult a dermatologist and stop using the product. Once you find a product that works for your skin, most retinoids will start working on your skin in about a month, but it may take longer for results to become visible. The longer you use a product, the better the effects will be and the more tolerable it will become, says Rahman. She advises not to mix too many products with active ingredients into your skincare routine. “It can disrupt the skin’s barrier that protects the skin from irritants and locks in moisture,” she says.