Hand sanitizer is here to stay, but it’s not without risks. Here’s what doctors have to say

A woman and child used hand sanitizer at CambridgeSide mall earlier this year. Jessica Rinaldi/Globe Staff

From stores to schools to restaurants, hand sanitizer dispensers have become a fixture of our lives amid the COVID-19 pandemic.

At first, the product was hard to come by. A national shortage in March 2020 caused it to disappear from shelves and forced stores to limit the amount customers could buy. The demand was so great that numerous local distilleries became temporary producers.

All told, hand sanitizer sales boomed more than 620 percent in 2020, totaling about $1.45 billion, according to NielsenIQ. Manufacturers like GOJO Industries, the maker of Purell, expanded their operations to meet consumers’ needs.

Demand for it has tailed off, but it is expected to remain a fixture in stores and households even as the pandemic abates in many areas.

“I do believe the side benefits consumers saw last winter — in particular far lower cases of colds and flu — will mean that some of the habits we all picked up during the pandemic on sanitation will stay with us,” said Jon Hurst, president of the Retailers Association of Massachusetts. “And thus sales will continue to be higher than pre-pandemic.”

The near-ubiquitous nature of hand sanitizer is a net positive, several doctors said. But it’s not without risks and should not be overused.

“There is not a single thing any one of us does that doesn’t have both risk and benefit,” said Dr. Gregory Poland, an infectious diseases doctor at the Mayo Clinic. “The great benefit is the ease of use, and the demonstrated efficacy of killing viruses, bacteria, etc.”

The product’s risks stem from its contents. Most hand sanitizer is alcohol-based and must contain at least 60 percent alcohol to be effective, according to the Food and Drug Administration, which regulates the product as an over-the-counter drug. The concentrated alcohol kills any viruses and bacteria it comes into contact with by denaturing its proteins.

Two common alcohols, ethanol and isopropanol, are safe and effective sanitizer ingredients, doctors said. But a third, methanol, is not. It’s banned in the United States but allowed in other countries that manufacture the product for online sales, prompting multiple warnings last year from the FDA.

“Children can actually absorb enough methanol through their skin to be toxic,” Poland said. Individuals who ingest methanol are also at risk of blindness and death, according to the Centers for Disease Control and Prevention, which reported 15 cases in two states last summer.

Alcohols that are considered safe have possible downsides, too.

“There’s been some recent concern over whether the ubiquitous use of it might lead to vapors that could irritate people with hyperreactive airway disease,” Poland said.

The high concentration of alcohol also damages the outer layer of skin, said Dr. Abigail Waldman, a dermatologist at Brigham and Women’s Hospital.

“The skin is like a brick wall. You have these bricks that protect it and the hand sanitizer does such a good job that often it will create holes in that brick wall,” she explained.

That causes dry skin prone to itching and cracking. The damage also allows “pathogens from the outside to get in,” which increases the risk of bacterial infections, Waldman said.

Doctors, who are accustomed to such frequent use of hand sanitizer, compensate with ointments and lotions such as Vaseline and Aquaphor, she said.

Another downside of using hand sanitizer regularly is that it may lead to resistance.

“You can actually get resistance to the hand sanitizer, meaning the flora or the typical bacteria or viruses that you run into will develop resistance against whatever you’re using,” Waldman explained.

Resistance is more common with antimicrobial agents, like triclosan, which has been banned from hand sanitizers in the United States since 2019. But it has been shown that “you can get a little bit of resistance to even alcohol-based hand sanitizers,” Waldman said.

There’s also speculation that hand sanitizer may disrupt the microbiome, the ecosystem of innocuous microorganisms that typically live on our skin.

“These hand sanitizers wipe out the bad bacteria and viruses, but they also wipe out any good bacteria and viruses as well,” Waldman said.

There’s little research on the topic, but findings from other organs, like the gastrointestinal tract, suggesting that so-called “good bacteria” may serve a purpose.

“We just don’t know what the implications of that are,” she said. “More and more, we’re realizing that your normal skin flora actually maybe has some purpose in protecting you.”

What’s clear is that sanitizer is inferior to soap and water, which allows for a more thorough wash. Hand sanitizer can’t penetrate mucus, like the droplets that come from a sneeze, Poland said. It also can’t remove dirt, blood, or other solid particles.

That’s why there’s no reason to use hand sanitizer at home or in the bathroom, Poland said. But if you’re out and about, it’s worthwhile.

“Stores are not going to provide a running water trough and soap before entering their store,” Poland said. “I think the benefits far outweigh the risks when it’s an approved hand sanitizer, used properly, and soap and water isn’t available or not a feasible option.”

“I think it’s great that it’s so readily available now, but when you do have the opportunity to wash your hands with soap and water, do that,” Waldman agreed.

Sanitizer is also no substitute for vaccination. When it comes to preventing COVID-19, Poland said hand sanitizer is “one thousand miles behind” a shot.

But hand hygiene helps prevent other illnesses and should have been a priority long before the pandemic, he said.

“Remember that cleansing your hands is not just about preventing COVID; it’s about preventing rhinoviruses, preventing RSV, influenza, bacterial infections,” Poland said. “We should have been paying attention to this way before this.”

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