There's no shortage of skin care ingredients to know and try. Depending on your needs, you may be met with a range of derm-touted suggestions from vitamin C (brightening), retinol (cell turnover), alpha-hydroxy acids (blemish control), and oh-so-many more. Peptides also fall under the expert-approved category yet don't always get the spotlight they so rightfully deserve. 

This class of ingredients is most often found in two types of products: anti-aging creams (or healthy aging, as we like to call it) and barrier support. Once you dig into what they do, that'll make perfect sense. Here, our guide to peptides in topical skin care. 

One concern that comes up often when discussing peptides in skin care is that there are many kinds of peptides (some better studied than others). Each is unique in its efficacy and function. So treating peptides as a monolith is a bit misleading for the consumer. To understand the nuances of peptide research, you need to get technical. 

At the moment, these are the "most helpful" peptide ingredients on the skin care market says King: 

As we've noted, many peptide-containing products are marketed as either "for mature skin" or "for barrier support." Once you see the benefits, this will make sense. 

Additionally, the exact benefit you'll get from a peptide product depends on the types used. 

However, as King notes, the research on these peptides in topical formulations is still relatively new. "In general, more independent, larger, well-structured studies are needed to definitively evaluate these claims," she says. 

Generally, these are well tolerated by most individuals. (After all, your body makes its own peptides.) "If you have sensitive skin or have had an adverse reaction to peptide products in the past, use caution when trying a new one," says Greenfield. "Test it out on your outer cheek or forearm for a few weeks before applying it broadly."

Of course, check out the rest of the INCI list (aka the ingredient list) to make sure there aren't other ingredients that may trigger a reaction for your skin, and do a patch test prior to using. Again, this warning is especially true if you have sensitive skin, known skin irritants, or have an inflammatory skin condition. 

Peptides can technically be formulated into anything, but they're best suited for leave-on serums, creams, and lotions—here, they'll be able to do their best work. Additionally, you can look for them in body and face products, where they'll exert their wide variety of benefits head to toe. 

Peptides play nice with other ingredients and tend to be pretty stable. For that reason, they're generally OK to pair with other actives, such as antioxidants. 

If you plan to layer your peptide product with something else, just follow the general skin care step guidelines, which are as follows: face wash, toner, serum, cream, oil, and SPF. Most peptide options are going to fall in the serum or cream slot, and if it's the latter, you may consider adding another active ingredient underneath in the form of a serum. For example, you may try an antioxidant serum topped with your peptide lotion. If so, just be careful to introduce the products one at a time so your skin has time to adjust to each new product. 

Given peptides are used for their collagen-building benefits, one idea is to use them alongside other collagen-boosting ingredients. Vitamin C and E serums are some of our favorites as the antioxidants are a vital part of the collagen synthesis process. Not only is it necessary for stimulating internal collagen production, but it also helps stabilize existing collagen8 levels in the skin, essentially protecting all the hard work from the peptides. 

However, another route to take is to find a product that contains peptides along with other actives, such as retinol, hyaluronic acid, or coenzyme Q10. (See some of the products above!) This way, the formula is made in such a way that the two ingredients work together—and you have less concern about the ingredients interacting negatively. 

Peptides are also famously found in beauty supplements in the form of collagen peptides. In ingestible form, they work to support the skin and body from the inside out. (And in case you're curious, yes there's loads of evidence collagen supplementation works.) We have plenty of collagen supplement content, so if that's your primary interest, check out a few of our favorite guides:

Peptides seem to be a highly effective way to support your skin barrier, promote collagen, and enhance skin texture as you age. While there is much to be learned about the different amino acid chains, the research so far is promising. Plus, they pair easily with most ingredients—such as retinol and vitamin C—so you can further optimize your skin longevity.