The rapid spread of coronavirus (or COVID-19) has people clearing out shelves of hand sanitizer across the US. And if you try to buy it online, most of it is out of stock or marked up in price. The shortage has spurred people to begin making their own hand sanitizer, using recipes from Twitter, Reddit, Pinterest and countless blogs. But just because these recipes exist doesn't mean you should bother. The issue is to get the right ratio of ingredients. The Centers for Disease Control recommends using a hand sanitizer that contains at least 60% alcohol, which store-bought hand sanitizers have. But trying to replicate that on your own can be tricky. The typical ratio is 60% alcohol to 40% aloe vera gel by volume, or 2/3 rubbing alcohol to 1/3 cup aloe vera gel. Mixing it at home, you can't control how the alcohol gets diluted in the final product, especially when many recipes call for a mix of 91% or 99% isopropyl alcohol. If you don't use enough aloe gel, it will dry out the skin on your hands, which can cause it to crack or bleed. But if you don't use enough alcohol, the final product won't be as effective at killing germs as store-bought hand sanitizer -- rendering it basically useless according to some experts. You can also contaminate your batch with bacteria by not using clean tools to mix it together. The final issue is that because of the popularity of these homemade hand sanitizers, the ingredients are now harder to come by. So even if you want to make it, you might not be able to find rubbing alcohol and aloe vera at your local drugstore. Perhaps it's best to fight the spread of any virus by washing your hands with soap and water, which is more effective in protecting yourself than using hand sanitizer.