Lip-plumping glosses have ingredients that irritate the lips in order to cause the temporary "plumping" effect, also often described as a "bee sting" look or a "puffy pout," according to the experts I spoke with.
Clinical dermatologist Dr. Shari Marchbein says, "Lip plumpers aim to give a temporary bee-stung look to the lips without the discomfort of [lip filler injections] — and the risks and side effects that go along with that [procedure]. Many traditional lip plumpers use various ingredients that irritate the delicate skin of the lips to produce a noticeable increase in lip volume."
Clinical dermatologist Dr. Joshua Zeichner adds that lip plumpers also work to moisturize the lips while causing the mild inflammation in order to keep the lips feeling healthy and moist over the time that the effect takes place.
Cofounder of Le Jolie Medi Spa Brian Nourian notes that, while Le Jolie offers lip fillers as one of their services, many of his clients turn to lip-plumping glosses when they're in a bind for an event, or if they want to see what lip enhancements might look like. He says, "There is no downtime after using them, and they offer instant results." He continues, "If you're thinking about going under the knife, they're also a noncommittal way to enhance your natural lip shape and see what your lips look like slightly enhanced if you've never gotten fillers or injections."