For example, copper peptides have in fact been shown to improve wound healing, which is partially why people started putting them in cosmetics. But, as Dr. González explains, those results may not transfer to skin-care benefits: “Wounded and healthy skin have different topographies, so we don’t know if [copper peptides] work the same on healthy skin,” she says. Several studies ended up finding that cosmetics containing copper peptides do promote smoother, healthier skin, but it’s still not clear if the same wound-healing mechanism is responsible for those results.
There are some peer-reviewed studies that test the efficacy of peptide products on actual human skin, and the results suggest that peptides seem to actually work. However, these aren’t the huge, double-blind clinical studies we’d all love to see—and they’re usually carried out by skin-care and pharmaceutical companies. According to Dr. González, this in itself isn’t automatically concerning: “Skin-care companies do good studies sometimes,” she says, but the studies still aren’t usually large enough to draw any huge conclusions. (The largest study we encountered was this 93-person experiment from 2005. Most had 15 to 40 participants.)
Claims around peptide serums are not FDA-regulated
From a consumer perspective, the most important thing to understand about peptides is that as with most skin-care products, they’re “cosmeceuticals.” This is not an FDA-regulated classification; it’s a marketing term that implies a cosmetic product has “medicinal or drug-like qualities.” (And those qualities may be used to justify higher prices.) But cosmeceuticals are not drugs—at least, not according to the FDA.
As long as they don’t claim to cure a disease or alter the structure of your skin, peptides aren’t subject to the same FDA regulations as, for example, retinoids, salicylic acid, or benzoyl peroxide. This also means that peptides haven’t been studied as extensively as drugs, SELF explained previously, so we don’t know as much about how they work.
Usually when people hear “cosmetic regulations,” they immediately picture, like, an eyeshadow palette crammed with illegal or irritating ingredients. But contamination isn’t typically the issue with cosmeceuticals. Instead the problem is how they’re labeled. When you buy a product that contains an actual drug, the label must list its concentration and the specific form used in the product. The same is not true of cosmetics—and therefore cosmeceuticals—no matter how scientific the product or its claims sound. There’s generally no way to know the concentration of peptides in a moisturizer, and in some cases it might not even be obvious which ones are in there.
Still, dermatologists love ’em.
Given the amount of favorable evidence out there, it’s not surprising that experts were pretty pro-peptides. “Having reviewed the literature, and also anecdotally in my own practice, I think they do promote thicker skin,” says Dr. Stevenson, who uses a peptide product in her routine. But she recognizes that peptide products are expensive and might not be as splurge-worthy as other options that definitely work: “Anyone who’s putting down a reasonable amount of money on [antiaging skin care] should prioritize lasers and neurotoxins (a.k.a. Botox)—and a good relationship with a dermatologist.”
Peptides vs Retinol
Okay, so peptide creams can’t match the wrinkle-busting power of Botox and lasers. But what about retinoids, the other gold standard in collagen reg