Does Alcohol Kill Fungi?

One of the most common uses for alcohol in its more pure forms is that of a germicide and sterility agent, with certain types and percentages of alcohol being deemed appropriate for the purposes of killing certain types of microbial life in the correct setting.

Among these types of microbes specifically targeted through the use of alcohol is that of fungi – eukaryotic microorganisms that may take the form of mold, yeast or mushrooms, depending on the particular species.

Fungi can and is regularly killed or otherwise rendered inert through the use of alcohol, especially in hospital or clinical settings wherein sterilization is of utmost importance. 

However, not all types of alcohol are created equal, and stringent standards of quality apply when using alcohol to disinfect and sterilize an area.

What Sort of Alcohol Can Kill Microbes?

Depending on what type of microbe is to be killed as well as the surface that is being disinfected, the particular formulation and percentage concentration of alcohol that is required will also change.

More easily accessible formulations of alcohol such as 60-80% isopropanol rubbing alcohol for the purposes of skin disinfection are the most commonly used – especially for killing any microscopic fungi that may be present on the individual’s skin.

When specifically disinfecting surfaces that contain significant populations of fungal spores or fungal colonies, it is best to utilize non-ethanol formulated alcohol at a moderate to high concentration percentage, as ethanol alcohol has been shown to not completely kill certain types of fungal species.

This is especially applicable in a clinical setting wherein even a small volume of fungal spores or fungal colonies present on medical implements can lead to fatal cases of infection.

How Does Alcohol Kill Microbes?

The particular mechanism of alcohol that is responsible for its wide reaching and effective ability to kill microbes is that of its protein denaturing effect.

When denaturation takes place between alcohol and a microbial life form, the alcohol affects any protein compounds present in the microbe’s cellular structure – essentially destroying the cell wall’s capacity to retain its shape and thereby rupturing and exposing the contents of the microbe’s cells.

The time it takes to do this and whether or not the alcohol is sufficiently powerful enough to pierce the structure of the microbe’s body will depend on a variety of factors such as what formulation of alcohol is being used as well as what type of microbial life is undergoing the denaturing.

In the case of fungi, yeasts are generally found to be far more susceptible to alcohol induced protein denaturation than other types of fungi – primarily due to the thickness and molecular complexity of the protein based structures encompassing said other types of fungi. 

Is it Hard to Kill Fungi with Alcohol?

It is actually quite easy to disinfect a surface contaminated with fungal life forms – so long as the proper tools are utilized for a sufficient enough period of time.

Though ethanol alcohol at a percentage over 50% is enough to kill some types of fungi, it is the use of 70% isopropyl alcohol that is most often recommended for the purposes of truly removing most traces of fungi and other microbes from a surface.

This is due to the fact that ethanol is more geared towards killing viruses enveloped in a protective protein layer, a form of microbial life several steps removed from that of fungus and therefore making isopropyl alcohol the more effective tool in killing the aforementioned life form.

Does Alcohol Kill All Fungi?

Though alcohol is an extremely effective disinfecting agent in regards to its germicidal and fungicidal abilities, it is not entirely foolproof, and either due to random chance or a certain type of fungal species with a particularly thick envelopment – it is possible for fungal species to survive alcohol disinfection.

This is more applicable if the sort of alcohol that was used is either of too high or too low a concentration, both of which will not act sufficiently enough in the manner of protein denaturation to wipe out every fungal spore and fungal colony of a surface.

What Percentage Alcohol Kills Fungi?

70 percent isopropyl alcohol
Editorial Credit: MikeEdwards / Depositphotos.com

Bright Future Recovery outlines that alcohol is usually diluted to a percentage below 100% with either water or a similarly neutral compound for the purposes of improving its microbe killing abilities or preventing skin irritation, if external skin usage is the purpose of the alcohol based product.

The particular percentage recommended by most reliable sources is that of 70% isopropyl alcohol, especially in regards to the killing of fungal spores and other types of fungal life.

This is due to the fact that any percentage of isopropyl alcohol that is too concentrated may result in the alcohol failing to fully penetrate the cell wall’s protein structures, only damaging the fungal cell wall instead of fully rupturing and destroying it.

By addition of this characteristic of 70% concentrated isopropyl alcohol, the addition of water as a diluent compound will also allow the alcohol to denature enzymatic proteins alongside the normal denaturing ability of alcohol in concerns to structural proteins.

Can Alcohol Kill Fungal Infections on the Skin?

Though alcohol is normally used as a disinfecting agent on non-biological surfaces such as tables or equipment, it is possible for isopropyl alcohol of the correct percentage concentration to be used in order to kill skin level fungal infections.

Much like if one were disinfecting a surface that was not skin, it is best to make use of isopropyl alcohol that is at a 70% concentration strength with the other 30% primarily being water so as to avoid any allergenic or adverse effects.

To do so, one simply needs to apply the alcohol directly to the area with a fungal infection, leaving the alcohol to dry or soak for a short period of time so as to kill any fungal colonies that it comes into contact with.

This, of course, will only be effective if the fungal infection is only at the surface, and deeper infections will not be affected or touched by the use of topical alcohol application.

References:

  • Widmer A, Frei R. 2011. Decontamination, Disinfection, and Sterilization, p 143-173. In Versalovic J, Carroll K, Funke G, Jorgensen J, Landry M, Warnock D (ed), Manual of Clinical Microbiology, 10th Edition. ASM Press, Washington, DC. doi: 10.1128/9781555816728.ch11
  • Ribeiro MM, Neumann VA, Padoveze MC, Graziano KU. Efficacy and effectiveness of alcohol in the disinfection of semi-critical materials: a systematic review. Rev Lat Am Enfermagem. 2015 Jul-Aug;23(4):741-52. doi: 10.1590/0104-1169.0266.2611. PMID: 26444178; PMCID: PMC4623738.
  • LOEWENTHAL K. The Antifungal Effect of 70% Ethyl Alcohol: A Laboratory Study. Arch Dermatol. 1961;83(5):803–805. doi:10.1001/archderm.1961.01580110091014