How Does Hand Sanitizer Work?

How Does Hand Sanitizer Work?

In the midst of the COVID-19 health care pandemic, more people are using more hand sanitizer than ever before. Although people have flocked to store shelves and tried to buy crates of the stuff, very few people fully understand how hand sanitizer works and why it’s so valuable in a coronavirus-driven crisis. Let’s examine hand sanitizer in-depth, determine exactly how it helps keep you from getting sick, and explain where soap and water can still be an effective tool in your repertoire.

What Is Hand Sanitizer, Really?

Hand sanitizer is a type of cleaning product distinct from soap and water. While soap and water are the best solution to clean your hands and other surfaces, sanitizer provides a convenient cleaning agent when both are not available.

According to the FDA, hand sanitizers can only legally be called such if they have ethyl alcohol (or ethanol), benzalkonium chloride, or isopropyl alcohol (isopropanol) as their active ingredient. If the hand sanitizer uses a different active ingredient from these three, it’s not an actual sanitizer and may not be effective at killing most germs.

Hand sanitizers are created by combining their active alcohol-based ingredient with a carrier liquid, which is usually either water or water plus another ingredient to add texture or consistency. The carrier liquid makes sure that the alcohol content spreads evenly throughout the solution and enables it to be spread easily across the skin. Otherwise, the alcohol would concentrate on the initial application area and soak into the skin too much, drying it out excessively.

How Does a Hand Sanitizer Clean Your Hands?

A hand sanitizer works primarily through the actions of alcohol. The water acts as a carrying agent to deliver alcohol to germs and across the skin, and to dilute its effects on your skin. In other words, alcohol can kill the germs on your hands. 

Alcohol and Its Role

Alcohol and its various forms are fairly simple organic molecules made up of hydrogen, oxygen, and carbon atoms. Ethanol is the most common – it’s the type of alcohol people drink. The other two major types of alcohol, isopropanol and propanol, are more common in disinfectants because they are more soluble in water.

Alcohol works by physically dismantling the proteins that make up the outer shells of various cells and viruses. In other cases, the alcohol can alter a cell’s metabolism and make it difficult or impossible for it to survive or reproduce. In general, solutions like hand sanitizer with higher concentrations of alcohol are more effective at this task.

The CDC recognizes that a concentration of about 60% is what you need for a hand sanitizer to be antibacterial and effective at getting rid of most bacteria and viruses. They’ve also discovered that concentrating alcohol at the 90 to 95% range caps the solution's effectiveness. Of course, you couldn’t go 100% without eliminating water entirely (and creating a solution that would be uncomfortable, to say the least, for human skin!).

Hand sanitizer is regarded as very effective at eliminating bacteria and some viruses because, unlike other viral or bacterial countermeasures, there’s no way for these organisms to develop a resistance against alcohol. It’ll always be effective at dismantling proteins, so it never becomes ineffective like certain types of antibiotics.

Furthermore, some types of infectious disease-causing bacteria like Serratia marcescens, Escherichia coli, and Staphylococcus saprophyticus are particularly affected by ethanol and, thus, hand sanitizers.

When applying hand sanitizer, you don’t need to use an entire bottle or coat your whole hands in the solution. Unlike with soap and water, hand sanitizer primarily works by making an inhospitable environment for germs on your skin for some time after initial application. Spreading the hand sanitizer over the surface area of your hands, even in a very thin layer, can do wonders for increasing your skin’s sterilization.

The use of hand sanitizer should be about the size of a quarter usually enough to coat both hands when rubbing the solution between your palms. Hand sanitizer can be used repeatedly without too many negative side effects, aside from hand dryness. This can be alleviated through a moisturizing salve.

Are Some Germs Resistance To Hand Sanitizer?

Despite its general effectiveness, hand sanitizer isn’t a one-size-fits-all solution for all types of germs. Several common bacteria and viruses like norovirus or cryptosporidium are well known to be resistant against alcohol and its protein-destroying effects.

Instead, soap and water are better at removing these types of germs and several other species of bacteria. People also usually use more soap and water over the surface area of their skin compared to the same application of hand sanitizer. 

What Else Does Hand Sanitizer Not Remove?

Additionally, hand sanitizer is limited in the fact that it does not remove any harmful chemicals, pesticides, heavy metals, or other foreign materials that could cause infection or poisoning in a wound. This is why soap and water is a superior cleaning solution overall; it can also get rid of physical threats in addition to organisms like bacteria and viruses.

Hand sanitizer works best in a clinical setting like a hospital for health care workers and healthcare professionals. In these situations, hands may come into contact with various germs but they aren’t usually dirtied by big debris or grease. On the flipside, hands that are dirty from playing outside, doing work, or otherwise interacting with the world may find soap and water to be a better solution.

Does Hand Sanitizer Go Bad/Expire?

Fortunately, hand sanitizer doesn’t expire like advertisements or manufacturers might have you believe. Expiration dates are printed on hand sanitizer bottles, as these products are firmly regulated by the FDA. They have a flat rule stating that expiration dates need to be on every product’s packaging regardless of whether it makes sense.

In hand sanitizer’s case, the expiration date refers to the last date that the product will contain the ingredients in the amount specified on the label. In essence, it’s the last date when evaporation won’t significantly affect how much sanitizer is in a bottle.

Alcohol is normally a shelf-stable chemical, meaning that, as long as it’s contained in a bottle at room temperature and is sealed, it’ll stay at the same concentration for a very long time. This doesn’t protect it from evaporation as the bottle is opened and closed, of course. 

Is Hand Sanitizer Toxic?

In general, alcohol is considered to be a safe compound for use as an antiseptic. It doesn’t normally have a toxic effect on the skin aside from causing dryness or irritation. One of the ways in which alcohol can cause adverse side effects on the skin is by absorbing moisture in the upper layers of the dermis. Thus, if you already have dry skin, applying a hand sanitizer might cause discomfort.

That being said, applying hand sanitizer multiple times over the course of a day is less irritating than repeatedly hand washing with soap and water. Soap and water can eventually damage your skin, making you susceptible to infection or more harm from germs over time. 

Of course, hand sanitizer should never be drunk or applied to overly sensitive skin. It’s primarily intended as a hand hygiene product because that skin is tough enough to withstand alcohol’s effects and tends to be a concentration point for germs that can be spread to other parts of the body.

Are Some Hand Sanitizers Better Than Others?

Yes. Some hand sanitizers have better balances between their percent alcohol content, water content, and any other carrier compounds that can make the product smoother or gentler on the skin. Most good hand sanitizers won’t have too many ingredients, however.

For instance, Green Goo’s Hand Sanitizer is a simple formula with ethyl alcohol as its active ingredient. At a alcohol concentration of 63.5%, it’s a little over the FDA recommended levels for effectiveness against most types of bacteria and viruses that are weak against alcohol. But it also contains inactive ingredients like carbomer.

This gel mixes with water and provides a soluble solution to spread the rubbing alcohol throughout the sanitizer evenly. As a result, those who use this sanitizer will experience consistent and potent results throughout the lifespan of the bottle, instead of dollops at the bottom being stronger than drops at the top.

In general, look for hand sanitizers that don’t have too many ingredients and that are FDA-approved. If a hand sanitizer isn’t FDA-approved, it’s not a hand sanitizer at all and may even have some toxic or poisonous ingredients in its formula. Be wary of hand sanitizers that have an excessive scent; this element is not necessary for the formula to be effective and may just make the sanitizer pricier than it needs to be.


All in all, hand sanitizers work pretty simply and perform wonders when used correctly. It’s not a full replacement for soap and water but it can be a great way to keep your hands clean when you don’t have soap and water on hand or if you don’t have time for a full wash. It’s definitely recommended to keep a bottle on hand for your day-to-day cleanliness, especially when washing hands is more important than ever before.

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