Do you want to stay healthy and avoid getting viral infections or stomach bugs from foodborne illnesses?

Washing your hands well is the key to avoiding getting sick, and you might be wondering exactly how to wash your hands most effectively. Does good, old-fashioned soap or hand sanitizer work better?

The great news is that regular, inexpensive soap works better than hand sanitizer to kill germs and viruses.

How could this possibly be true?

Well, it’s all about chemistry, says Dr. Daniel Pastula, a UCHealth neuro-infectious disease expert and neurohospitalist at UCHealth University of Colorado Hospital.

Why does soap work better than hand sanitizer for hand washing?

Pastula said soap is a simple but highly effective tool.

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,” said Pastula, who is also an associate professor of neurology, infectious diseases and epidemiology for the University of Colorado School of Medicine and the Colorado School of Public Health.

In more recent years, humans discovered that alcohol can kill bacteria and viruses like the one that sparked the COVID-19 pandemic in 2020. Hand sanitizer is made up mostly of alcohol, so sanitizers have become a popular choice as people pay more attention to washing their hands and preventing the spread of viruses.

Does hand sanitizer kill viruses? Why does soap work better?

While hand sanitizer can neutralize viruses, 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.

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.”

Does the type of soap you use matter?

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

“It can be fancy mall soap. It can be a 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 viruses. 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.

Does it matter how long I wash my hands?

The chemistry of soap is fascinating as well, Pastula 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 coats viruses like the one that causes COVID-19? 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, so it’s important to spend at least 20 seconds lathering up and washing your hands.

What about the temperature of the water? Does that matter when you’re washing your hands?

When you wash your hands, Pastula said you don’t worry too much about the temperature of the water (as 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, Pastula said it’s a great option when you’re on the go and can’t access a sink.

But when you’re near a bathroom or kitchen sink, make use of the simplest, cheapest way to wash your hands and avoid getting sick.

Said Pastula: “Soap is simple, cheap, and incredibly effective.”