Is A High-Concentration Rubbing Alcohol Always Best For Disinfecting?

A simple combination of water and isopropyl alcohol, rubbing alcohol is one of those products you might think has relatively limited use. Yet rubbing alcohol is about as multifaceted as it gets. As a disinfectant, not only is it effective in sanitizing surfaces, but it can also be used to rid your makeup brushes, foul-smelling shoes, and even your armpits of certain bacteria, fungi, and viruses, according to experts at the Cleveland Clinic.

However, not all rubbing alcohol is made the same. Rather, rubbing alcohol is available in both lower concentrations, as well as higher concentrations of up to 99% (via WebMD). "Lower concentrations aren't as good at killing germs," Dr. Sarah Pickering Beers told the Cleveland Clinic. "But very high concentrations can be harsher when used on the skin." Knowing this, is it better to choose a high-concentration rubbing alcohol or a lower-concentration rubbing alcohol when it comes to our disinfecting needs?

A higher concentration percentage doesn't necessarily mean you're getting a deeper clean. "The 70% variety tends to be a good choice for most household uses," Dr. Beers tells the Cleveland Clinic. The reason being is that 70% isopropyl alcohol contains more water than rubbing alcohol with a higher concentration. This means that the chemical breaks down at a slower rate and more effectively infiltrates and kills off contaminants (via WebMD). For this reason, you'll want to avoid rubbing alcohol with a concentration of 80% or higher as its disinfecting ability diminishes. 

To get the most effective clean, start by washing the affected object or surface with water and soap. Then, spray or wipe down the area using 70% isopropyl alcohol. It's important to note that you should not further dilute the solution by adding in any more water, according to Healthline. Rather, use it just as is. Allow the product time to work by letting it sit for about 30 seconds or more.

While rubbing alcohol does have disinfecting benefits to offer, it is classified as an intermediate-level disinfectant (via Essentials of Medical Biochemistry). Therefore, it shouldn't be thought of as a high-level sterilant, as noted by researchers in a 2010 study published in the Journal of the American Association for Laboratory Animal Science that looked at how effective 70% isopropyl alcohol was at disinfecting surgical tools and gloves used in mouse surgical procedures. Following each procedure, surgical equipment was soaked in a sterile bowl of 70% isopropyl alcohol for two minutes, and used glove fingertips were soaked for 30 seconds or more. The study findings revealed that the rubbing-alcohol soak effectively prevented aerobic bacterial contamination of materials used, but only in five out of the ten mice surgeries.

Overall, while rubbing alcohol may be helpful when it comes to household chores, WebMD cautions that it is not an effective means of sterilizing medical equipment and advises against it.