The differences between bar soap and liquid soap

• Both liquid soap and bar soap are effective against bacteria and viruses, but they have slight differences.
• Liquid soap can be less drying, since it tends to have added moisturizers.
• But the friction created by rubbing bar soap against your hands can be more effective at removing visible debris like dirt.
• This article was medically reviewed by Graham Snyder, MD, MS, who is the medical director for the Infection Prevention and Hospital Epidemiology branch at University of Pittsburgh Medical Center.
• Visit Insider's homepage for more stories.

Good hand-washing habits are crucial to staying healthy, especially right now in the wake of the COVID-19 pandemic.

When choosing the type of soap for your daily cleaning, you want to make sure you're selecting the most effective option. Here's what you should know about the difference between liquid soap and bar soap for handwashing.

Bar soap and liquid soap are equally as effective

Soap, whether liquid or bar, will reduce the number of pathogens on your hands. The friction you create when you're rubbing your hands together and lathering up lifts away dirt and microorganisms, and the water then rinses them off.

Additionally, soap of any variety is particularly good at deactivating certain types of viruses, including SARS-CoV-2. That's because this virus is what's called an enveloped virus, meaning it contains an outer membrane of lipid, or fat. Maloy says that soap molecules are effective at dissolving this membrane, which deactivates the virus, essentially killing it.

Both experts say that whether you decide to use bar soap or liquid soap in your home simply comes down to personal preference. You won't be more protected or less protected if you choose one or the other, as long as you're washing your hands properly and for a long enough time – at least 20 seconds. It's also important to remember that antibacterial soap is not necessarily more effective at killing germs than regular soap.

According to Whyte, bar soaps can accumulate some bacteria when they stay out in the open for a long time, but there's really no data to suggest any harm from it. The chances of actually getting sick from bacteria on the soap are very slim. But, if you live with multiple people (a family or a few roommates) and somebody in the household is sick, and you don't want to take any chances, you might feel more comfortable using liquid soap to prevent further germ spread.

The advantages and disadvantages of liquid and bar soaps

There are various pros and cons associated with both liquid and bar soaps. But surprisingly, they really don't have to do with the soap's effectiveness at removing and killing germs. Here's the breakdown.

Liquid Soap

Advantages

• Tends to keep the area around the sink more tidy (no wet bar soap residue).
• Soap dispensers make for easy, convenient use.
• Often has added moisturizers to prevent hands from getting dry.
• And a bonus, there are more scents and varieties available.

Disadvantages

• Liquid soap is usually more costly than bar soap, according to John Whyte, MD, WebMD Chief Medical Officer. For example, according to the CVS online store, Dial's Gold Bar Soap ends up being 16.7¢ per ounce, while Dial's Liquid Gold Soap amounts to 26.7¢ per ounce.
• Foaming liquid soap may not be as effective as traditional liquid says Stanley Maloy, PhD, Associate Vice President for Research & Innovation at San Diego State University. This is because liquid soap has to be worked up into a lather, which encourages more thorough hand washing, whereas foam soap is dispensed already sudsy.

Bar Soap

Advantages

• The friction created by rubbing the bar against your hand can be more effective at removing debris like visible dirt, says Whyte.
• Usually more cost-effective than liquid soap.
• Bar soap is a more sustainable option. It usually comes in boxes made of thin cardboard, which uses less material than the thick plastic that liquid soap bottles are made of. Plastic takes at least 100 years to decompose in a landfill. On the other hand, cardboard packaging takes a few months to decompose. A 2009 study in Environmental Science & Technology determined almost 20 times more energy is required in product packaging for plastic soap bottles than producing cardboard or paper packaging for bar soap.

Disadvantages

• It tends to dry out skin more easily than liquid soap due to its high pH which can have a dehydrating effect.
• Used bar soaps can get slimy or mushy, which isn't a threat to your health, but may appear unsightly.

The bottoms line is that a good, thorough handwashing with liquid or bar soap is crucial because not only does it prevent you from transferring any pathogens to another surface or person, but it also makes it less likely for you to introduce pathogens to your mouth, eyes, or nose if you touch your face.

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