The pitch comes in the form of before and after photos posted to Facebook or Instagram by a woman you know. The focus is on her eyes, specifically her eyelashes, which at first appear ordinary and untouched — a stark contrast from a picture taken weeks later, when they look long and thick. Mascara magnifies the effect in another snapshot.

Reach out, the captions enthuse, if you want in!

Such pictures have increasingly populated social media this year from women selling an eyelash enhancing serum from Rodan & Fields, a skin care company that distributes most of its products through independent “consultants.” One might expect the average woman to be skeptical about the idea of applying a little-known liquid to her eyelids every night in hopes of longer lashes a month later, especially without a prescription. It is the kind of thing that, if seen on a television infomercial, might be skipped without a second thought.

But fueled by social media testimonials and a robust direct selling force, the serum, Lash Boost, briefly sold out this summer, and the company said that sales of the product — which costs up to $150 — should top $175 million in its first year.

The popularity illustrates the modern dynamics of direct sales companies, which were once mostly associated with door-to-door Avon visits and social gatherings. In the social media era, selfies are the new Tupperware party, influencing the types of products the companies can persuade people to buy.

“Our business is really based on the visible results of the products that we sell,” said Lynn Emmolo, chief brand officer of Rodan & Fields. “The consultant connection to their friends and the visible results — that’s where the magic happens.”

Lash Boost has been a particular success for Rodan & Fields, which last year topped Neutrogena and Olay to be the top skin care brand in the United States, according to Euromonitor, a market research company. Rodan & Fields, which was founded by the dermatologists who developed Proactiv acne products, said it had more than $1 billion in annual revenue overall, with items like blemish- and line-reducing face creams.

It is certainly not novel for women to seek longer, darker eyelashes, but the means of achieving that have moved beyond mascara and the prescription drug Latisse, which was introduced in 2009. Women are increasingly visiting salons for individually applied lashes every few weeks, turning a special-occasion treatment typically associated with weddings into something as routine as a manicure. Fake eyelashes that stick with magnets instead of glue were introduced last year, intended to make daily application easier. And, as with Lash Boost, personal testimonials and photographic evidence on social media helped fuel sales.

“I thought, this is a product that will go viral because lashes make everyone look better, particularly in pictures — that’s why a lot of brides get them,” said Katy Stoka, the creator of the magnetic lashes, known as One Two Lash. She added, “Then it came in tandem with the obsession with the selfie.”

Direct selling is used to promote everything from fitness shakes to jewelry to leggings online, but beauty products are particularly popular. (Roughly three-quarters of those involved in direct selling are women, according to the Direct Selling Association.) Makeup, broadly, “does so well on social because it’s very dramatic,” said Larissa Jensen, a beauty industry analyst at the NPD Group.

Dr. Amy Newburger, a dermatologist who advised the Food and Drug Administration on a variety of products for more than a decade, said Lash Boost was similar to a slate of other enhancers that emerged after Latisse was introduced that contain cosmetic, over-the-counter versions of the drug’s active ingredient.

Based on its chemical makeup, it’s “not unique by any stretch of the imagination,” she said. “What is very effective is they have excellent marketing.” Newburger added that such products can have a visible effect on lashes and eyebrows, but that she considers them “uncharted territory” because of the proprietary formulations each brand creates to achieve the results and the limited testing performed on cosmetics more generally.

Because Lash Boost is a cosmetic and not a drug, the company is careful to avoid saying that it causes lashes to grow. Instead, it uses language centered on appearance, promising “fuller-looking” and “longer-looking” lashes. Consultants for Rodan & Fields are given dos and don’ts for their social media posts that advise them on lighting, as well as examples of compliant language (“I have noticed longer-looking lashes”) and noncompliant phrasing (“My lashes are longer”).

Lesley Russo of Raleigh, North Carolina, who started selling the company’s products about two years ago, said she had seen an especially enthusiastic response with the lashes on Facebook.

“It grabs people’s attention more because the eyes are front and center,” she said. Russo said she liked working with Rodan & Fields partly because it was not a party-based business and she can sell the product using social media and email outreach conducted from her couch. (Some people involved in direct selling still go the tried-and-true route and set up parties where they demonstrate their products.)

Russo said many women use Facebook to hold “online parties,” where they will invite people to a page at a specific day and time and then post about the products. Sometimes, they will also incorporate live video, she said, adding, “It’s great because you can reach people all over the country.”

Of course, plenty of people have griped about the deluge of direct-selling overtures from friends and acquaintances on social media. An improv comedy group composed of two mothers in Arizona made a popular video this month that poked fun at the topic called, “If You’re My Friend Then You’d Buy This.”

“Honestly, the two of us are sick of getting all this information from friends we haven’t heard from in years, where all they’re interested in is making money off of us,” said Michelle Fortin, one half of the duo. Still, she said, “the before and after pictures are definitely eye-catching.”

In fact, Fortin said, her comedy partner had just bought Lash Boost and believed it was working.

© 2017 The New York Times Company