Essential Oils as Antibiotic Agents

Essential Oils as Antibiotic Agents

Alternatives to conventional Western medication take many forms from nutraceuticals to healing touch, from acupressure/acupuncture to aromatherapy.  They are thought to treat a variety of conditions and have been used over millennia and in many cultures.  This paper focuses on essential oils, specifically their antibacterial effects and usage as an alternative or adjunct to pharmaceutical antibacterials.

The Rise of Antibiotic Resistant Bacteria

More and more we are encountering drug and multidrug resistant (MDR) pathogens.  These pathogens, including bacteria, are becoming increasingly deadlier and costlier to treat as we exhaust of options to treat them (Allen, 2017).  The development of new antibiotics is always one route; however, concern about resistance to those new antibiotics is warrented (Hrvatin, 2017).  We need to look to alternatives, both singularly and in combination with traditional therapies to meet this challenge.  Essential oils are one method that have been around and are gaining in popularity and attention (Herbs uses, history, essential oils, n.d.; Yap, Yiap, Ping, & Lim, 2014).

Background and significance

Essential oils were the precursors to many medications.  They have been used for an indeterminant time (Aromatherapy: History and basics, n.d.; History of essential oils, n.d.).  They have been used in India in ayurvedic therapy, in China, in Egypt, in Greece and Ancient Rome, etc. (Aromatherapy: History and basics, n.d.; History of essential oils, n.d.).  For a time, in Catholic Europe, their use was considered witchcraft but was kept alive, it is thought, by monks who continued the science in secret (History of essential oils, n.d.).  By the 1700’s, their use was becoming more common and widespread again.  Even during the Indochine War, the French physician Jean Valnet used essential oils to treat war wounds successfully when antibiotics ran out (Aromatherapy: History and basics, n.d.; History of essential oils, n.d.).  They could be extracted from everyday plants such as clove, garlic, eucalyptus, and more to create effective medications for the everyday person.  Blends of essential oils were used to combat the bubonic plague, most notably, “thieves’ oil” which legend has it protected grave robbers from the plague while they were in contact with the infected bodies (Young Living Essential Oils).  Currently, in the United States, essential oils are available for use in inhalation and topical applications (PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board, 2019).

We know that essential oils have many properties.  Clove oil, for instance, has a main component of eugenol which has pain relieving and antimicrobial properties (Yap, Yiap, Ping, & Lim, 2014).  Many know that aspirin was originally extracted from willow bark and used as an analgesic, frequently brewed as a tea for ingestion.  The applications of oils address a variety of needs.

Review of Literature

Many essential oils have antibacterial properties among other properties.  Among these are clove oil, rosemary oil, citrus oils, oregano oil, basil oil, and mentha oil (Chavez-Gonzalez, Rodriguez-Herrera, & Aguilar, 2016).  All of these have been shown to have properties effective against drug resistant bacteria, some against multidrug resistant bacteria (Chavez-Gonzalez, Rodriguez-Herrera, & Aguilar, 2016; Abdullah, Hatem, & Jumaa, 2015).  These are examples of some of the more recent studies that have been done on essential oils and their antibiotic effects. These look at essential oils and/or their components against more than one type of bacteria.

Oregano and thyme oils have as a major component the phenol carvacrol (Magi, Marini, & Facinelli, 2015).  Carvacrol has shown more effectiveness against gram-positive bacteria than against gram-negative in its bactericidal activities; its mechanism of action (MOA) is to damage bacterial membranes (Magi, Marini, & Facinelli, 2015).  It also has a synergistic effect with  antibiotics, including macrolides (Magi, Marini, & Facinelli, 2015).

Streptococcus pyogenes

is a Group A streptococci (GAS) bacteria that can have mild to severe consequences if an infection develops.  GAS can cause relatively mild disease such as impetigo all the way to necrotizing fasciitis and shock.  It can also have post-streptococcal sequelae like rheumatic heart disease, post-streptococcal glomerulonephritis, and more.  GAS has developed increasing resistance to the main macrolide that is used to treat it, erythromycin (Magi, Marini, & Facinelli, 2015).  While oregano and thyme oils showed inhibitory GAS bacterial growth, the best GAS growth inhibition was a combination of carvacrol and erythromycin (the tested strains were erythromycin-resistant GAS strains) (Magi, Marini, & Facinelli, 2015).  This shows potential for use in clinical applications and the development of safe drug combinations to administer to those who contract GAS (Magi, Marini, & Facinelli, 2015).

Rosemary and clove oils were tested against MDR strains of several bacteria, both gram-positive and gram-negative, as well as two standard strains (Abdullah, Hatem, & Jumaa, 2015).  The four strains of MDR bacteria were

Acinetobacter baumanni


Pseudomonas aeruginosa


Staphylococcus aureus

, and

Enterococcus faecalis

(Abdullah, Hatem, & Jumaa, 2015).  The two standard strains used were

Pseudomonas aeruginosa

ATCC 27853 and

Staphylococcus aureus

ATCC 29213 (Abdullah, Hatem, & Jumaa, 2015).  Rosemary oil showed inhibition in all six bacteria when in concentrations of five percent and greater but only in two bacteria when in weaker concentrations (Abdullah, Hatem, & Jumaa, 2015).  Clove oil showed inhibitory growth for all six strains at a much greater level, including in concentrations as low as 1.25%, and in three of the strains at a concentration of only 0.312% (Abdullah, Hatem, & Jumaa, 2015).  This leads to the conclusion that while rosemary oil can be used as an antibacterial agent (and is a potent option), clove oil is a more potent option (Abdullah, Hatem, & Jumaa, 2015).

Four components of several essential oils, carveol, carvone, cintronellol, and citronellal, were tested against

Escherichia Coli


Staphylococcus aureus

.  All provided some inhibition to bacterial growth with one notable exception: carvone to

Staphylococcus aureus

(Lopez-Romero, Gonzalez-Rios, Borges, & Simoes, 2015).  Citronellol had the highest inhibitory effect followed by citronellal against both pathogens (Lopez-Romero, Gonzalez-Rios, Borges, & Simoes, 2015).  Citronellol and citronellal are both components of

Eucalyptus citriodora

which is a varietal of eucalyptus (Lopez-Romero, Gonzalez-Rios, Borges, & Simoes, 2015).  Based on how these components affected the two tested bacteria, it was concluded that they would be useful in topical applications for skin infections (Lopez-Romero, Gonzalez-Rios, Borges, & Simoes, 2015).

Relevance to Advanced Practice

As advanced practitioners, we will encounter multidrug resistant bacteria often.  Advanced practitioners must educate themselves in alternatives to the traditional Western medicine.  Dealing with these bacteria will be something we cannot avoid, and we must look to alternatives and complementary therapies to combat them.  This can include essential oils.  Many oils (and their components) are generally recognized as safe (GRAS) for usage and are widely available (besides the fact that some are commonly used for cooking in their plant form) (Chavez-Gonzalez, Rodriguez-Herrera, & Aguilar, 2016; Boire, Reidel, & Parrish, 2013).  Information on how to use them can be found on the internet; much of it is unreliable as there are few sources or references for the claims listed.  This is a concern as an advanced provider as the patient might choose to use essential oils without considering them medicine (they may affect other medications) and they may be utilizing them in an unsafe way.  Arguably a reliable website that commonly comes up on searches is; their articles are written and reviewed by professionals with sources listed (About us, n.d.).  This is not the case for many sites.  Being able to steer patients to reliable sources is important in educating them, be it about essential oils, diseases and conditions, and more.  Patients must also be cognizant of the fact that some forms of usage are better than others (indeed, some forms of usage may be deadly) and that use should be carefully considered.


Essential oils are a viable alternative and/or adjunct to traditional therapies in the treatment of pathogens, especially MDR ones.  Their application in not limited to antibacterial applications but also include other microbials such as fungus (Dagli, Dagli, Mahmoud, & Baroudi, 2015).  There should be concern that microbes will do what they have done since the beginning of time, evolve to withstand these additional agents. Research must continue developing ways to combat them.  It is necessary to discover the toxic levels (such as neurotoxicity) and side effects so that dosing can be safely determined (Dagli, Dagli, Mahmoud, & Baroudi, 2015).  In the meantime, as additional therapies are being developed, it is the wise primary care provider (and the acute care provider) not to dismiss essential oils as the province of those who distain Western medicine but to learn more about them, their uses, and their applications.


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