For obvious reasons, hand sanitizer is becoming a piece of everyday carry equipment, nearly as important as a phone, wallet, or keys. The question is, are you using it properly? It's entirely possible that you're not.
How Hand Sanitizer Works
Hand sanitizer is generally little more than a gel-like suspension of alcohol in a substance that keeps it thick and less messy to use.
The active ingredient is, of course, the alcohol. Alcohol denatures proteins, essentially tearing them apart. When applied to your hands, it won't shred through your skin, but immersing something like a virus or bacteria in it is enough to destroy that virus or bacteria. 
There's some interesting science behind how alcohol works to do this, but that's more than we really need to get into. Suffice to say that the primary mechanism of hand sanitizer is exposure to alcohol.
What this means is that, to properly use hand sanitizer, you need to apply enough of it, rub it in thoroughly, and make sure it covers all surfaces of your hands. More on the process in a moment, though.
Picking the Right Hand Sanitizer
The first thing you want to do is pick the right kind of hand sanitizer. Remember that if you're using a hand sanitizer properly, you're using it frequently. Since hand sanitizer is based on alcohol, it can dry out your skin and lead to painful cracks and dry flakes all over your hands. This does more harm than good.
A good hand sanitizer needs to have a high enough concentration of alcohol to make it effective. Some hand sanitizers are meant to be more of a peace of mind lotion or a placebo than they are an actual effective treatment.
The trouble here is that some hand sanitizers don't list how much alcohol is in their concentrations. If they do, you're looking for something with at least 60% alcohol. Some people recommend a concentration of at least 40%, but 60% is the ideal minimum. You will rarely see anything higher than 95% because at that point it's harder to keep the gel consistency. Higher alcohol concentrations can be found in alcohol wipes and other cleaning products, though. Most hand sanitizers are at least 60% alcohol by volume.
There are "natural" hand sanitizers on the market you can try if you want. They have ingredients like thyme, bitter orange, and lavender, all of which are known to have at least some antimicrobial benefits. However, there's no scientific proof that these are anywhere near as effective as alcohol.
It's also worth noting that alcohol is also a natural ingredient. The alcohol used in hand sanitizer is typical ethanol, or ethyl alcohol, which is simple grain alcohol. Some of the other ingredients included in hand sanitizers might not be natural, though. A naturally formulated hand sanitizer should still have a sufficient quantity of alcohol to be effective.
Other potential ingredients include perfumes, glitters, and soaps. Perfumes aren't going to affect the efficacy of hand sanitizer one way or the other. Glitters can be useful for when you wash your hands later, to make sure you're being thorough, but in general, they're just an aesthetic choice. Soaps, meanwhile, can increase the efficacy of hand sanitizer somewhat, though it still won't be as good as pure soap and water.
Other choices, such as the brand name of the hand sanitizer, don't really matter. The alcohol is pretty much all you should be truly concerned with.
How Much Hand Sanitizer Should You Use?
When you choose to apply hand sanitizer, you need to make sure to get enough. Getting too little means you won't have enough alcohol on your hands to fully sanitize their surface, which means you're not truly sanitizing your hands. Getting too much, meanwhile, means you're wasting some of this currently relatively scarce product.
The appropriate amount of hand sanitizer is a roughly dime-sized dab of the stuff. If you have particularly large hands, you might want a little bit more, while if you have small hands, a smidge less will do. It's generally fine to err on the side of too much rather than too little.
Rather than simply rely on this article, however, you want to check the label on the product you're using. Some hand sanitizer brands have slightly different formulas and prefer you to use more or less than the normal amount. They will have instructions for using the hand sanitizer, which you should follow preferentially over other directions.
Cleaning Your Hands First
One mistake many people make when they're using a hand sanitizer is not making sure their hands are relatively clean first. Unfortunately, hand sanitizer has one critical drawback compared to soap and water: you're not able to rinse your hands off afterward.
What this means is that if you're in a position where your hands are dirty, such as if they're greasy from working on machinery, dirty from working on plants, or covered in grime from cleaning dirty surfaces, hand sanitizer will be less effective.
Before applying hand sanitizer, you should make sure to clean your hands as much as possible. We get that this isn't always available to you, and that hand sanitizer is often the only option you have. In these cases, applying more hand sanitizer may be necessary. You want to try to get it under the grime that's stuck to your hands because that grime can be trapping other contaminants.
The ideal course of action, of course, is to wash your hands with soap and water. You can save the hand sanitizer for later when your hands are relatively clean but you don't have access to soap and water.
How to Apply and Use Hand Sanitizer
As mentioned above, you want to clean your hands if possible, and you want to apply a dime-sized dab of hand sanitizer. Apply this dab to one palm.
At this point, you want to follow a guide similar to the CDC's handwashing guide, or the guides for healthcare workers using sanitizer regularly. Make sure to rub the hand sanitizer over every surface of both hands, including palms, between the fingers, the backs of the hands, the thumbs, and the wrists. Pay special attention to fingertips, cuticles, and under nails. This is where contamination can build up and should be cleaned more thoroughly.
How long should you rub in the hand sanitizer? Estimates vary, and it will depend slightly on how much hand sanitizer you're using. You want to be rubbing it in for at least 20-30 seconds. General recommendations for hand sanitizer are to rub it in until you feel it evaporating and it is no longer sticky when you rub your hands together. This is when the gel and other ingredients have absorbed into your skin and the alcohol has evaporated.
The Drawbacks to Hand Sanitizer
Hand sanitizer is not a replacement for soap and water. In fact, the stuff is really only useful as a supplement to cleaning when you don't have regular access to soap and water. This is why healthcare workers use it when moving in and out of patient care areas, and why they regularly wash their hands with soap and water throughout the day.
That's not to say that you shouldn't use hand sanitizer. Using it is better than not using anything at all. That said, there are a few drawbacks to hand sanitizer that you should be aware of.
First, hand sanitizer does not rinse your hands. While it does kill most microbes that are on your hands when you use it, the dead microbes are still on your hands. Even if hand sanitizer is 99% effective, that 1% remaining might be a potential route for contamination later as well. 
Repeat cleaning with hand sanitizer may get less effective if you aren't able to rinse and wash your hands in between. This is because the residue of hand sanitizer builds up, and the accumulated dead microbes, grime, dirt, and residue all reduce the effectiveness of the hand sanitizer.
This, as mentioned above, applies when your hands have other kinds of dirt on them as well. Hand sanitizer works best in clean clinical settings where hands are exposed to germs but are not coated in dirt or grease. Thankfully, this means it's useful in natural daily settings like grocery shopping as well.
It's also worth mentioning that hand sanitizers do a good job of killing most microbes, but they are not 100% effective. Some kinds of germs, like norovirus and c-diff, can survive through hand sanitizer more than they can through soap and water.
Luckily, the current pandemic virus, the coronavirus, is effectively destroyed by the proper use of hand sanitizer. Just make sure you're using enough of it and using it thoroughly enough. Simply slapping a dab on your hands and giving them a three-second rub is not enough.
It's also important to note that hand sanitizer is effective against things like germs and microbes, but they do not work against things like toxic chemicals, heavy metals, or pesticides. If you're exposed to some kind of chemical, you will need at least soap and water, if not a potential medical treatment for the more caustic kinds of exposure. Of course, if you're in a position to be handling these kinds of substances, you should be wearing gloves.
When to Use Hand Sanitizer
When should you be using a hand sanitizer? In general, it's a good thing to use after you touch something that may be contaminated. For example, if you visit a healthcare facility, you should sanitize your hands with soap and water before touching anything, and then use hand sanitizer after touching things throughout the facility. When you go to leave, then, sanitize your hands with soap and water again.
Hand sanitizer should also be used when you're out and about and risk exposure. You don't need to over-do it, though. For example, when you leave the house, you don't need to use hand sanitizer between your home and your car. You can use it before entering a store, and then use it once you're done checking out, but you don't need to use it every time you touch a product in the store.
You should also use hand sanitizer when you do something that might contaminate your hands. For example, if you cough or sneeze into a hand, you need to sanitize that hand. You can do this with hand sanitizer, though of course soap and water is the better alternative.
The same goes for handling animals or animal waste. Using hand sanitizer after having contact with animals is important to avoid the spread of any kind of disease the animal might be carrying. The current pandemic came from animals, after all.
It's entirely possible to use hand sanitizer in conjunction with gloves and hand washing as other methods to keep your hands clean. The most important things to remember are that you should be washing your hands with soap and water thoroughly and often, and you should avoid touching your face. Practicing safe conduct when coughing or sneezing is also important. Wearing a mask if you're sick can help keep you from spreading germs to those around you as well.
The simple fact is that far too many people do too little when it comes to hand sanitizer. They use too little of it at a time, and they don't rub it in thoroughly enough or for long enough. If you remember that more is better – more sanitizer, more time, more coverage – you'll be ahead of the game.
