CNN
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They can plump your lips like a reality star’s. They can smooth over wrinkles and even shape your nose.

Injectable fillers, which contain materials like hyaluronic acid or collagen to give your skin or features a cosmetic boost, are growing in popularity around the world. Along with other cosmetic procedures, fillers have become popular holiday gifts.

In the United States, the use of fillers soared from 1.8 million procedures in 2010 to 2.6 million in 2016, according to data from the American Society of Plastic Surgeons.

Among those millions of procedures, which are minimally invasive, most are performed in a safe and effective way, with few adverse side effects. Yet with a rise in popularity, the overall number of complications has also climbed.

A paper published Thursday in the journal JAMA Facial Plastic Surgery spotlights both common and rare complications associated with fillers, and raised in litigation, in the US.

“The paper demonstrated that fillers are very safe and that the most common complications are swelling and infection, which are relatively benign complications, with no permanent side effects,” said Dr. Hani Rayess, an otolaryngology resident in the Wayne State University School of Medicine in Detroit and lead author of the paper.

On the other hand, blindness is an extremely rare complication that has received attention in recent years.

“This research is important because fillers are being increasingly used for facial rejuvenation,” Rayess said. “It is important for patients to understand the risks, alternatives and benefits prior to receiving fillers.”

The cost of fillers ranges from several hundred to thousands of dollars.

Dermal fillers approved by the US Food and Drug Administration include Restylane, Juvederm Vollure, Juvederm Volbella, Juvederm Voluma, Radiesse, Sculptra and Belotero.

The FDA warns against using unapproved versions of Juvederm. The agency also notes that it has not approved liquid silicone or silicone gel for injection to fill wrinkles or augment tissues anywhere in the body.

For the new paper, researchers analyzed data from the FDA’s manufacturer and user device experience database, which contains medical device reports of suspected deaths, injuries and malfunctions. They searched for adverse events from injectable fillers reported between January 1, 2014, and December 31, 2016.

The researchers also analyzed data from the American Society of Plastic Surgeons on the overall projected number of filler injections performed during that time, and they analyzed litigation and court records related to fillers in the Westlaw Next Database.

The researchers identified 1,748 reported events involving injury between 2014 and 2016. Of those, the most common complications were swelling, infection, the presence of a nodule or lump, and pain. Many cases – 43% – stemmed from a cheek injection, and 30% were from a lip injection, the researchers found.

“Swelling comprised about 0.01% of all injections,” Rayess said

Blindness was involved in eight injections in the study, and nasal injections were significantly associated with blindness, the researchers found, though rare.

For instance, among Radiesse injections, the researchers found that only .0001% resulted in blindness.

Globally, only about 50 cases of blindness after aesthetic facial injection have ever been reported, according to a study published last year in The Journal of Clinical and Aesthetic Dermatology.

Though it’s a rare risk, what’s the connection between the nose and the eye that could lead to such a severe complication from nasal injections?

“Blood vessels around the eye and nose tend to be the most dangerous because they’re in continuity with the blood vessels in the back of the retina and the back of the eye,” said Dr. Daniel Maman, a board-certified plastic surgeon at 740 Park Plastic Surgery in New York, who was not involved in the new paper.

The researchers also found nine court cases associated with fillers, five of which were resolved in the defendant’s favor. Of the cases that resulted in a monetary payment, the researchers found that the average amount awarded was about $242,000.

“To our knowledge, this study is the most wide-scale analysis of reported complications of filler injections,” the researchers wrote.

The paper came with limitations, however, including that the data for the overall number of injections were based on American Society of Plastic Surgeons surveys that are then extrapolated to produce total injection numbers and that the FDA’s database can suffer from under-reporting.

“Adverse events are supposed to be reported to the FDA, so it’s good to use their database to analyze what complications have been reported in this way. That being said, it is limited by the fact that such reporting is voluntary and may not be as comprehensive as we would like,” said Dr. Clark Schierle, director of aesthetic surgery at Northwestern Specialists in Plastic Surgery and a board-certified Northwestern Medicine plastic surgeon in Chicago.

“The public should understand the take-home message that these injectable treatments tend to be very safe and effective,” added Schierle, who was not involved in the new paper.

A concern among doctors has been the significant number of physicians not trained in plastic surgery, or professionals who are not even licensed physicians, who are injecting fillers or performing other cosmetic procedures.

“If you’re an under-the-radar, non-board-certified practitioner, you’re probably also less likely to report the adverse event properly to the authorities,” Schierle said.

“If you actually look at the data, probably these were all reported by people that were above board, because they’re volunteering the information to the FDA,” he said about the new paper.

On Instagram, for instance, only 17.8% of plastic surgery-related posts in the US and Canada appear to come from board-certified plastic surgeons, while the majority are from non-board-certified professionals, according to a study published in the Aesthetic Surgery Journal in August, of which Schierle was a senior author.

In the new paper, the researchers “did divide these complications by the filler type, but it would be useful to see the complications categorized by provider, which type of physician is most likely to be associated with a severe complication,” said Dr. Matthew Schulman, a New York City board-certified plastic surgeon who was not involved in the study.

“I would think that board-certified plastic surgeons, facial plastic surgeons and dermatologists would be less likely than non-board-certified physicians to see severe complications after injections,” he said.

Even though data in the new study did not include information on the injector – so a connection between adverse events and non-board-certified injectors could not be made – Rayess agreed, “we would expect a rise in complications with less-qualified injectors.”

As it turns out, some filler procedures are thought to be by non-board-certified professionals, said 740 Park Plastic Surgery’s Maman.

“Meaning family practitioners, dentists, nurse practitioners, gynecologists, dermatologists, pretty much any specialty you can imagine. All you need is a MD to buy the filler from the company,” Maman said.

“The problem with that is that they’re injecting this substance below the skin into an anatomic area that they have no idea what the underlying anatomy is,” he said. “When a plastic surgeon or an (ear, nose, throat) surgeon for that matter injects the material, we know exactly what layer we’re in; we know where the nerves are; we know the potential pitfalls, where the dangerous blood vessels are.”

Maman warned that patients should know who is injecting them before they go under the needle.

“Certainly, a board-certified dermatologist, plastic surgeon or ENT surgeon are the only people who should really be injecting,” Maman said. “Be very careful about going to medi-spas or any of these spa clinics where you have no idea who’s injecting you, what specialty they’re in or what certifications they have.”

Schulman said at-home lip-filler kits are emerging as “a very dangerous trend” now available in the United Kingdom and Canada, and there has been concern that the products might trickle into the US.

“The potential dangers include infection, deformity, blindness and even death,” he said. “It is important to select a properly qualified injector who has extensive knowledge of the anatomy and has knowledge of how to treat complications if they occur.”