Ask a Doc: Do Fist Bumps Spread Fewer Germs than Handshakes?
Sep 04, 2019 Cedars-Sinai Staff
Shaking hands is a custom that dates back centuries, but it's not uncommon to see people opting out, especially during flu season or when a bug is going around.
One alternative to shaking hands is the fist bump—but is there any science behind the notion that fist bumps transmit fewer germs?
We asked Dr. Michael Ben-Aderet, associate medical director of Hospital Epidemiology.
Q: Does fist-bumping spread fewer germs than handshaking?
Dr. Michael Ben-Aderet: There is some evidence that handshakes, because of the increased duration and the pressure applied, transmit more germs than fist bumps.
That has been proven in a couple studies, but the studies are a little artificial because they've really covered people's hands with bacteria—or with a marker meant to simulate bacteria—and then looked at how much bacteria gets transferred. It's much more bacteria than anyone would expect to encounter in their day-to-day life.
The studies did show a lower risk of contamination with a fist bump than with a handshake, but with good hand hygiene the actual risk of contracting germs from shaking hands is really low.
Q: Does the outside of our hands carry fewer germs than the palm?
MBA: Your skin is colonized with what we call skin flora: a community of bacteria and fungi that is normal on the body.
It helps keep us healthy and repels the germs that can make us sick. This flora is highly variable depending on the location on the body and is different from the inside to the outside of your hands.
In general, the germs that make us sick don't live on the skin—they are not a part of the normal flora but are picked up from the environment.
So the inside of the hand is likely to be more contaminated because you're more likely to touch things with your palm versus the outside of your hand.
Q: What's the best thing people can do to avoid germs when they shake hands?
MBA: Practicing good hand hygiene is the most important thing.
Using an alcohol-based hand solution before and after shaking someone's hand is the best way to avoid germs. After you do something that soils your hands, wash your hands with soap and water. After you do something that touches someone or yourself, wash your hands.
Proper hand hygiene is extremely effective in removing pathogens, whether it's viruses, fungi, or bacteria.
Q: What is the best way to clean your hands?
MBA: At home, washing both sides of your hands with soap and water is sufficient. Most people are not coming in contact with the same degree of germs as, say, hospital workers treating patients.
Alcohol-based hand sanitizers that are 60-90% alcohol are highly effective, especially if you're in a situation where you can't wash your hands.
Using enough hand sanitizer to fully cover the surface of your hands and last about 15 seconds before it dries is sufficient to kill almost all of the germs from shaking hands with somebody. And they kill pretty much all the commonly acquired respiratory viruses, like the flu.
If you have soiled or wet hands, you should wash them with soap and water.
Q: Is there any risk from cleaning your hands too much?
MBA: Dry hands are more likely to spread germs than well-moisturized hands, so if you're going to be using a lot of hand sanitizer or washing your hands frequently, you should definitely be using a regular hand moisturizer as well.