Does Alcohol Kill Germs on Skin and Surfaces?

Published March 11, 2020
Woman using hand sanitizer

If you're one of the many people wondering, "Does alcohol kill germs?" the short answer is yes. However, as with most scientific and medical things, the true answer to that question is a lot more complex. While some types of alcohol kill some types of germs, most big health organizations recommend the use of soap and water over alcohols for skin or surface cleaning.

Does Alcohol Kill Germs?

According to the Centers for Disease Control and Prevention (CDC) guidelines for disinfection and sterilization in healthcare facilities, there is evidence that some alcohols successfully kill germs. Sterilization refers to procedures that destroy or eliminate all forms of microbial life while disinfecting procedures eliminate some pathogenic, or disease-causing, microorganisms, or germs, on inanimate objects like surfaces. However, there's also evidence that these same alcohols sometimes fail to prevent infections. Because of these discrepancies, the Food and Drug Administration (FDA) hasn't cleared any specific disinfectants or sterilants that have alcohol as their main active ingredient for use in healthcare settings.

What Are Germs?

A germ can be defined as "any microscopic organism that causes disease." Generally, the most common types of germs people are concerned about are bacteria and viruses.

What Is Alcohol?

Alcohols are types of organic compounds that contain a series of hydroxyl compounds. In healthcare terms, the word "alcohol" typically refers specifically to two types of alcohol, ethyl alcohol, commonly known as ethanol, and isopropyl alcohol, commonly known as rubbing alcohol. Because some alcohols can eliminate some disease-causing germs, alcohol is a disinfectant. There are different types of alcohol that work best at killing different types of germs on different types of surfaces. Whether you're cleansing skin or a surface, health officials recommend that you always clean with soap and water first if you can.

Do Alcoholic Beverages Kill Germs?

While alcoholic beverages like beer do contain ethanol, they don't typically contain high enough concentrations to be used as disinfectants for skin and surfaces.

Does Alcohol Kill Bacteria?

The CDC guidelines further explain that ethyl alcohol and isopropyl alcohol do kill bacteria, but they don't necessarily stop it from spreading and don't destroy bacterial spores, or individual cells capable of reproducing. Alcohols help destroy parts of bacteria because they change the structure of the proteins that make up the bacteria. Alcohols alone don't work as good at destroying bacteria as alcohols mixed with clean water because water helps change the structure of the proteins too. In general, the CDC says a 60% to 90% solution of alcohol in water is optimal for killing bacteria. However, different types of bacteria require different alcohol solutions and exposure times to be effective.

  • Pseudomonas aeruginosa, which causes pneumonia, is killed in 10 seconds by all concentrations of ethanol from 30% to 100%.
  • E, coli and Salmonella typhosa are killed in 10 seconds by all concentrations of ethanol from 40% to 100%.
  • Staphylococcus aureus, the bacteria in MRSA, and Streptococcus pyogenes, which causes scarlet fever, are killed in 10 seconds by ethyl alcohol concentrations of 60%-95%.
  • Isopropyl alcohol (isopropanol), the alcohol found in rubbing alcohol, is slightly better at killing bacteria than ethyl alcohol for E. coli and the bacteria in MRSA.
  • Methyl alcohol, or methanol, is the weakest medical alcohol in terms of killing bacteria.

Does Alcohol Kill Viruses?

The CDC guidelines also indicate that some alcohols do kill some viruses. For example, ethyl alcohol at concentrations of 60%-80% can inactivate viruses like herpes, vaccinia, influenza, adenovirus, enterovirus, rhinovirus, and rotaviruses. But, ethyl alcohol at this concentration does not kill, or inactivate, hepatitis A. Some studies have shown that ethyl and isopropyl alcohol do inactivate hepatitis B and ethyl alcohol can also inactivate HIV.

Using Alcohol to Kill Germs on Skin

Using alcohol to cleanse skin should only be done when soap and water aren't available, says the Mayo Clinic. In instances where you have mucus on your skin from something like sneezing onto your arm, alcohol won't be very effective because the mucus protects the bacteria from being destroyed by the alcohol. The Cleveland Clinic adds that this the best way to clean superficial wounds because antiseptics can damage healthy tissue.

Disinfecting a wound with alcohol

Alcohol Wipes for Skin

Many healthcare facilities use wipes containing alcohol to clean skin before injecting a needle to prevent the spread of germs from the outside of your skin to the inside of your body. For this to work, the skin surface needs to be clean before the wipe is used. Most disinfecting wipes for skin contain 70% isopropyl alcohol, which is within the recommended concentration for using alcohol to kill germs.

Choosing an Alcohol Based Hand Sanitizer

If you are using a hand sanitizer to kill germs, make sure it is an alcohol based hand sanitizer (ABHS) because that is the only kind of hand sanitizer that is proven to kill germs. These sanitizers need to be used properly to kill bacteria on your skin. A 2020 scientific review of alcohol based hand sanitizers found that most hand sanitizers contain isopropanol, ethanol, n-propanol, or a combination of two of these alcohols. Ethanol seems to be the most effective against viruses, but propanols are better at killing bacteria, so a combination of these two would seem ideal. An ABHS is effective at preventing the spread of seasonal flu, H1N1, URI, and other viral or bacterial diseases, but not norovirus.

Experts suggest the following hand sanitizer guidelines:

  • Choose a sanitizer that contains 60% to 95% alcohol.
  • If the main active ingredient is ethanol, look for a 60% to 85% solution.
  • If the main active ingredient is isopropanol or n-propanol, look for a 60% to 80% solution.
  • Hand sanitizers were meant to cleanse the surface of skin, not open wounds.

How to Use Hand Sanitizer

The proper procedure for using hand sanitizers is:

  1. Apply 2.4 to 3 ml. of the hand sanitizer to the palm of one hand. Check the label to find out the appropriate amount.
  2. Rub your hands together.
  3. Rub the sanitizer over all the surfaces of your hands and fingers for at least 20 to 30 seconds or until your hands are dry.

Using Alcohol to Kill Germs on Surfaces

Because alcohols don't kill bacterial spores, the CDC does not recommend using them as the only means for sterilizing medical and surgical materials or surfaces. A 2014 World Health Organization (WHO) report further warns that, since alcohol is flammable, it should only be used to disinfect small surfaces in well-ventilated spaces. Using alcohol on surfaces over long periods of time can also damage the surface, making it unsafe.

Disinfecting door handle

Using Ethanol to Soak Small Items

According to Stanford University, a 70% ethanol solution with water can be used to soak small, nonporous items like surgical equipment, such as tweezers. You can also use it to wipe down surfaces after a potentially corrosive disinfectant was used. Because this solution would need to sit on larger surfaces for ten minutes or more before drying, it's not appropriate for decontaminating large surfaces like counters.

Using Alcohol to Clean Larger Surfaces

If you plan to use alcohol like ethyl alcohol and isopropyl alcohol to clean a large surface such as a counter top, experts at Virginia Tech suggest a 70% solution with water. When alcohols are diluted below 50% in a solution or above 90% in a solution, they become less effective.

  • The solution must remain in contact with the hard surface for ten minutes.
  • You should wipe the surface using a grid pattern instead of a circular pattern to keep from re-introducing contaminants to the surface.
  • Do not hand dry the surface or touch it while it's air drying.

Say Goodbye to Germs

Certain types of alcohols in specific concentrations can help you get rid of germs like bacteria and viruses on your skin or in your household cleaning routine. However, you certainly don't need to stock up on rubbing alcohol and ethanol to keep you and your loved ones safe from germs. A little scientific knowledge and some common sense can go a long way in helping you feel like you're as safe from germs as you can be.

Does Alcohol Kill Germs on Skin and Surfaces?