Good hygiene is important in the prevention of illness. In particular, you should always keep your hands clean by washing them regularly with warm water and soap, scrubbing them for at least 20 seconds before rinsing them and drying them off. Doing this helps prevent the spread of bacteria and reduces your risk of coming down with things like the common cold or influenza, as well as from acquiring other bacterial-related illnesses.

When soap and water isn’t readily available (i.e. when you’re outdoors, or don’t have spare minute to stop what you’re doing to go and wash your hands), carrying hand sanitizer can be beneficial. In particular, hand sanitizers that contain around 60 to 95 percent alcohol tend to be more effective at killing off germs than those with a lower concentration of alcohol or ones that are non-alcohol based. However, you also need to keep in mind that hand sanitizers are not effective in eliminating all types of bacteria – such as C. difficile as well as the parasite known as Cryptosporidium; nor can they kill off the food-borne virus known as Norovirus, which affects as many as 20 million people each year and is spread through the consumption of contaminated foods and beverages.

For the aforementioned reasons, washing your hands with soap and water is usually what’s best to protect against harmful germs and bacteria. In addition, new research which was published by Science Translation Medicine last year found that several strains of bacteria were becoming more tolerant to hand sanitizers, meaning that some bacteria were able to thrive for longer periods of time even when alcohol-based sanitizers ere used. The same study also found that enterococcal infections, which are caused by bacteria affecting the bladder, digestive tract and heart, actually increased – and while these different types of bacteria weren’t necessarily resistant to alcohol-based sanitizers yet, it was still a concerning find. To make matters worse, many strains of the bacteria that were part of last year’s study were also found to be resistant to multiple drugs, which meant there would be fewer treatment options available.

Along with not being able to fight off all strains of bacteria, hand sanitizer can also cause damage to the skin – especially if you’re overusing it. Hand sanitizers commonly contain alcohols known as isopropyl, ethanol and n-propanol, which can not only irritate the skin but also cause the it to become dry by stripping away its natural oil, cause skin cells to become dehydrated, and can even increase your risk of developing contact dermatitis – which develops when your skin comes into contact with certain substances, causing a red, itchy rash. The dryness caused by the alcohol in hand sanitizer can also lead to accelerated aging of the skin and an increase in the appearance of fine lines and wrinkles. Hand sanitizers also come in many different scents; to do this, they are made with chemical fragrances, and these can also be irritating to the skin and have even been linked to allergic reactions and the disruption of hormones, therefore if you do plan on using hand sanitizer, it’s best to use one that does not have any added fragrance to it.

You should also avoid the use of hand sanitizer if your hands are visibly dirty (for example, if you have been outside gardening), as they do not remove dirt. Instead, you’ll just wind up with a muddy mess on your hands and will ultimately have to clean them off with soap and water anyway. People also use hand sanitizer by habit, which can be a mistake. Using too much too often, or when it’s not necessary, is also what can lead to what’s known as antibiotic resistance, so if you are going to be using hand sanitizer then you should make sure you’re only using it when you need to and not simply because it’s sitting in front of you.