Peptide serums can address a wide variety of concerns, such as “reducing the appearance of wrinkles, improve the skin barrier, reduce inflammation, and promote elasticity,” says Melanie Palm, MD, a board-certified dermatologist in San Diego, CA.

Their exact benefit, however, largely depends on the peptide in question. “Signal peptides enhance production of collagen and elastin, while carrier peptides can help vital ingredients get to their target sites to increase collagen production,” says Dr. Castilla. Meanwhile, enzyme-inhibitor peptides can inhibit the enzymes that break down collagen, leading to lax skin and wrinkles.

One increasingly popular type of peptide is a neuropeptide, or “neurotransmitter inhibitor peptides,” says Dr. Castilla. This peptide can “block the release of neurotransmitters that relay muscle signals.” In other words, it acts similarly, albeit on a much smaller scale, as neuromodulators, relaxing the facial muscles to minimize expression lines.