Our Beauty P.I. series is where Makeup.com editor Alanna delves into the history and behind-the-scenes science of various makeup products — where they originated and how they’ve evolved. Next up on the list are lip plumpers. Lip plumpers are abundant in the makeup universe (the Lancôme L'Absolu Rôsy Plump is one of our favs) and if you use them on the reg, you’re no stranger to their familiar *tingling* sensation. Although everyone craves a good plump now and again, sometimes it makes us wonder what really is in the formulation of these magical lip-plumping products — what ingredients make it work? Fortunately, L’Oréal Associate Principal Chemist Roselin Rosario had some answers to our pout-plumping queries. Ahead, find everything you need to know.How Are Lip Plumpers Formulated?Because lip plumpers are a part of the lipstick family, they are formulated in a similar way, but, Rosario notes that there is one main difference: the addition of plumping ingredients. “Plumping ingredients such as capsaicin are included, as well as hydration ingredients to improve the overall look of the lips, and high shine for a volumized lip look,” she says. The plumping ingredients are included at a specific concentrations as well, to ensure their safety.      View this post on Instagram          RED for the Holidays? Celebrate with a bold look complete with eyes that sparkle, radiant skin and vibrant red lips. Get the look: 🌹L’Absolu Lacquer 134 Be Brilliant Make-up by @Lynseyalexander for @graziauk #Lancome #RedHotHolidays A post shared by Lancôme Official (@lancomeofficial) on Dec 12, 2018 at 10:51am PSTKey Ingredients in Lip Plumpers These ingredients are key in building lip plumpers differently from regular lip products, according to Rosario. “Lip plumpers contain active ingredients that cause plumping, which a normal lipstick does not contain,” she explains, “and most plumping ingredients work by causing a temporary mild irritation of the lips.” Capsaicin is often used, which is a compound found in hot peppers, as well as ingredients like peppermint and ginger that also cause a similar effect. “The tingling sensation is from these ingredients,” Rosario adds, “and it indicates that they’re working!”How Are Lip Plumpers Tested?Like other lip and makeup products from reputable companies, lip plumpers are thoroughly tested for safety and claims. “Tests are performed to ensure that the plumpers are safe to use and would not cause undesirable side-effects to healthy individuals using the product recommended,” says Rosario. The lip plumpers are also tested for efficacy — to ensure that they really work!Don’t Try This at HomeWhile lip plumping is meant for mild, temporary irritation, Rosario warns against trying a DIY version home. “People interested in lip plumping should choose a product from a reputable brand,” she says, “because DIY-ing a lip plumper without knowing the right concentration of an active ingredient and safety testing can cause mild irritation to turn into a serious effect.” And she’s right — with great lip plumping comes great responsibility, so practice it safely.Read MoreThe Best Lip Plumping GlossesHow Do I Apply Individual Lashes?The Best 5 Makeup Erasers 
