Why soap, water work better than hand sanitizer to remove coronavirus

By Katie Kerwin McCrimmon, UCHealth Today

It’s impossible to find any hand sanitizer at stores these days, but there are plenty of bars of soap on grocery store shelves.

And there’s a little known secret about good, old-fashioned soap, even if it’s the cheap, generic kind.

It works better than hand sanitizer to remove the coronavirus.

How could this possibly be true?

Well, it’s all about chemistry, says Dr. Daniel Pastula, a UCHealth neuro-infectious disease expert who recently assisted local public health officials in Summit County as the coronavirus sparked a spike of cases in their area.

Pastula is a neuro-infectious disease expert and neurohospitalist at UCHealth University of Colorado Hospital and an associate professor of neurology, infectious diseases and epidemiology for the University of Colorado School of Medicine and the Colorado School of Public Health.

Pastula said soap is a simple, but highly effective tool.

(Washing your hands for at least 20 seconds with any kind of soap works great for getting rid of the coronavirus. Pastula is a fan of Gloria Gaynor’s video showing her lathering up as she sings her song, “I will Survive.” Check it out below.)

Millennia ago, humans discovered that they could combine animal fat with alkaline salts or ash to create what we now call soap.

“And this combination did a remarkable job at cleaning,” Pastula said.

In more recent years, humans discovered that alcohol can kill bacteria and viruses like the new coronavirus that has sparked a global pandemic. Hand sanitizer is made up mostly of alcohol, so sanitizers have become a popular choice as people try to stay safe from the coronavirus.

While hand sanitizer can neutralize the coronavirus, it doesn’t have one little-known superpower that soap has.

“Soap disrupts the sticky bond between pathogens and your skin, allowing the pathogens to slide right off. Not only are you neutralizing the virus with the soap, but you’re also physically knocking it off your hands,” Pastula said. “Hand sanitizer doesn’t do all of that.”

So, public health experts truly mean it when they tell you that washing your hands frequently for at least 20 seconds with soap and water will help prevent the spread of the coronavirus. They also are begging all of us to please stay home and keep our distance from others so we can reduce the spread of the illness that this coronavirus is causing: COVID-19.

Many health care providers count on hand sanitizer and use it multiple times a day when they are seeing patients. They sanitize before seeing a patient. And they sanitize afterwards. They sanitize before seeing the next patient, and so on and so on. But, when Pastula has the opportunity, he heads to a sink.

“It’s just better,” Pastula said. “If I have the option, I use soap and water. I use hand sanitizer as a backup.”

As for the type of soap, it doesn’t matter.

“It can be fancy mall soap. It can be 50-cent generic unscented soap. It doesn’t need to be antibacterial soap. All soaps work the same,” Pastula said. “And soap doesn’t only work for this virus. It works on many other viruses and bacteria.

Pastula said the use of soap dates back to ancient times.

“The earliest recorded evidence of soap use was before 2000 B.C. in the Middle East. The ancient Egyptians described combining various plant fats with alkaline salts to create a cleaning substance they bathed in around 1500 B.C.,” Pastula said.

The chemistry of soap is fascinating as well, he said.

“Chemistry for the win here. Soap has two chemical parts to it: A head that is hydrophilic, meaning it likes mixing with water. And a tail that is hydrophobic, meaning it likes mixing with oils and fats. Typically water and fats/oils don’t like to mix. But when you add soap, they suddenly do,” Pastula said.

Just think about when you’re mixing a vinegar and oil dressing. You have to keep shaking the dressing because the oil and vinegar keep stubbornly separating.

“Soap can bridge the chemical differences between water and fat. That’s why you need soap to clean a greasy frying pan” Pastula said.

And that’s what makes it so effective.

“Guess what’s coating this particular virus? It’s a layer of fat,” Pastula said. “Soap molecules can pry themselves into the fatty layer of this particular virus and break it up, thus inactivating the virus.”

Breaking up the fatty envelope that encases the virus particles can take a little time.

“That’s one reason why you need to wash your hands for at least 20 seconds,” Pastula said.

When you wash your hands, don’t worry too much about the water (so long as it’s clean) or the exact type of soap. Just pay attention to lathering and washing long enough.

The water doesn’t have to be a particular temperature.

“Use whatever temperature is comfortable for you. The big thing is that you get all the surfaces on your hands lathered up, then rinse with water. That whole process takes about 20 seconds,” Pastula said.

With our dry climate in Colorado, plenty of people are noticing that their hands are dry and chapped from so much hand washing. Pastula said it’s fine to use moisturizer after you wash your hands. (You wouldn’t want to moisturize dirty hands, so wash them before you use moisturizer.)

With respect to hand sanitizer, “if you can find it, hand sanitizers are a great second option when you don’t have access to soap and water.”

But as we all do our part to try to halt the spread of COVID-19, Pastula urges us not to overlook the simple option most people can access.

“Soap is simple, cheap, and incredibly effective.”


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