Are Essential Oils Antimicrobial?

cartoon microbes

Today I’m looking for evidence that essential oils are antimicrobial. But what exactly is antimicrobial? Antimicrobial means that it prevents the spread of microorganisms (bacteria, some viruses, fungus, etc.) by inhibiting or killing them.
All essential oils are antimicrobial; some are just stronger than others. As you might imagine there is a ton of evidence for this one! But before we dig in it’s important to understand that every microbe is different. Because one essential oil is effective on one virus, doesn’t necessarily mean it will kill all viruses. And now for the exciting part! You know how some bacteria become resistant to antibiotics? That doesn’t happen with essential oils! The exact chemistry of each essential oil is dependent on so many factors (weather, geography, time of harvest, soil conditions, etc.) that their chemical composition is always different. Now, mix that one essential with another two or three and WOW!

Okay, let’s have a look at the evidence…
One 2017 study used a blend of cinnamon, carrot seed, eucalyptus and rosemary and a blend of cinnamon, carrot seed, oregano and clove. The first blend was successful against 14 strains of bacteria, some that were antibiotic resistant. It was also effective against the viruses H1N1 (like swine flu) and HSV1 (cold sores). The second blend was successfully against six Candida (fungus) strains.

Another study from 2019 looked at the research of nine essential oils. Lavender was shown to be antiviral to HSV1, antibacterial and antifungal and had a strong antiseptic against antibiotic resistant strains (including MRSA, E. coli). Thyme showed antiviral (HSV1) and antifungal activity but was particularly good at inhibiting the growth of bacteria. Peppermint showed high levels of activity killing HSV1 and HSV2 (genital herpes) but is a weak antibacterial. Cajeput is an effective antibacterial and is effective against some yeasts and molds. Cinnamon is active against the H1N1 virus and some bacteria (E coli, MRSA, etc.) and inhibited the growth of Salmonella, Listeria and some fungi. Clove inhibited HSV1 and HSV2 viruses, was active against some bacteria and fungi. Eucalytpus shows activity against viruses, bacteria and fungi and is toxic to MRSA and E. coli. Sage was active against SARS, bacteria and many fungi. Tea tree was active against some viruses, bacteria and Candida.

17 essential oils and nine essential oil compounds were tested on E. coli and Salmonella in 2004. The essential oils most active against E. coli were oregano, cinnamon leaf, clove bud, lemongrass, cinnamon bark and lemon. Those most effective against Salmonella were Melissa, oregano, lemon, lemongrass and cinnamon leaf.

In 1996, ten essential oils were tested for their antibacterial and antifungal activity against 22 bacteria strains and 12 fungi. Lemongrass, eucalyptus, orange and peppermint were effective against all 22 bacteria strains, with palmarosa and patchouli being very close to all 22. All 12 fungi were inhibited by citronella, geranium, lemongrass, orange, palmarosa and patchouli, with eucalyptus and peppermint being close to all 12. 

Essential oils are already used in toothpastes, mouthwashes, acne treatments, food packaging, etc. Hopefully we’ll soon find essential oils that are active against COVID-19!

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