Essential Oils: Our Allies Against Illness?

9 min read  |  June 03, 2022  | 
Disponible en Español |

Science is rediscovering the healing properties of plants and essential oils.

Aromatherapy … the word conjures pleasant scents, dim lighting, and soothing music. In short, a nice, relaxing spa day, right?

Yet, there’s much more to essential oils, those fragrant forces of nature used in aromatherapy. And scientists are taking notice.

“Aromatherapy is defined as the science of utilizing essential oil’s naturally occurring chemical components to affect change in the physical, mental, and emotional state. It is a real practice with specific uses,” says Cary Caster, LMT, CCA.

A botanist by training, Caster studied aromatherapy in the United Kingdom, where it is considered a medical treatment. She earned her advanced clinical aromatherapist certification in France.

Essential oils, also known as volatile oils, are aromatic oily liquids harvested from flowers, buds, seeds, leaves, twigs, bark, herbs, wood, fruits, or roots.

These small but mighty natural ingredients are surprisingly powerful.

As germs become increasingly drug-resistant and emerging diseases like COVID-19 pose a global threat, researchers are studying the ability of essential oils to fight bacteria, viruses, inflammation, and fungi.

It’s not a stretch.

Many of our pharmaceuticals were developed from plants.

Cary Caster, LMT, CCA, botanist

Case in point:

  • This study suggested using synthetic drugs and essential oils with proven physiological and chemical properties to fight COVID-19. The study noted that essential oils contain “multiple active phytochemicals (chemicals produced by plants) that can act synergistically (with each other) on multiple stages of viral reproduction.”

Some oils also have a positive effect on the respiratory system, including dilating the bronchial airways and breaking up mucus.

  • Another study said a wealth of data supports the long-held belief that tea tree oil (TTO) has antimicrobial and anti-inflammatory properties. While more clinical evidence is needed, the researchers called for “large randomized clinical trials … to cement a place for TTO as a topical medicinal agent.”
  • A scientific article cited a study showing that vapors from citrus bergamia, eucalyptus globulus, and their isolated compounds (citronellol and eugenol) showed rapid anti-influenza virus actions.
  • The same article mentioned another study demonstrating that lemon balm oil “inhibited plaque formation of HSV-1 and HSV-2 (herpes) viruses in a dose-dependent fashion.” It went on to say, “At higher concentrations, it abolished the viral infectivity almost completely.”
  • When given orally using proper methods, peppermint, tea tree, and thyme oil act as an effective intracanal antiseptic solution against MRSA, yeast, and E. coli infections.

On a lighter note, a University of Miami researcher found that babies given a bath in lavender-scented oil cried less and slept better than those bathed without it.

Why? The cortisol (stress hormone) levels significantly decreased in mothers and babies in the lavender oil test group. Other researchers found that lavender scents diffused in the air effectively controlled pain in premature infants.

How do essential oils work?

“All essential oils are made up of active chemical components. Lavender has 100 different components, for example. These naturally-occurring chemical components affect the permeability of the invading microbial (viral) cell membranes. They break down cell walls,” Caster says.

This means that certain oils can prevent viruses and infectious microbes from replicating or “nip it in the bud,” as Caster says.

“They keep the microorganism guessing. There seems to be an innate ability with essential oils to distinguish the difference between harmful versus beneficial microbes. However, not all oils possess this selective quality,”

Most doctors recommend yearly vaccinations to fight off different strains of the flu. Essential oils work similarly.

Take tea tree oil.

“It’s distilled yearly. It’s not the same every year, which helps with the inability of germs to develop any resistance.”

Plants have been around a lot longer than modern drugs and chemicals, and our bodies know it.

“We have receptor sites for the chemical components found in plants. They trigger certain olfactory and autonomic nervous system responses and are easier for our bodies to assimilate.”Caster says.

“Essential oils work synergistically with our bodies. They are tonifying (amplify the body’s energy), like taking vitamins to support the body.”

On the other hand, “We don’t yet know the implications of synthetic chemicals. Some people experience an over-sensitization to many products that contain synthetic fragrances.”

If a person loses their ability to smell because of COVID or another condition, essential oils can help. “Smell training” repeatedly exposes the person to strong whiffs of odors which stimulates the growth of the brain’s olfactory receptors.

“Olfactory stimulation generates new and/or strengthens existing connections,” Caster says.

Rose, eucalyptus, clove, and lemongrass oils are commonly used in smell training.

Harness the power of plants at home

Start by managing your expectations. There is time and place for conventional medical care. Although aromatherapy is effective in many ways, it’s a slower form of “medicine.” Think of essential oils as another way to support your physical and emotional well-being.

Even if they smell nice, plant-based oils are potent. Caster follows certain practices and precautions when using oils:

Dilute, dilute, dilute.

“Oils are extremely concentrated and penetrate quickly. Dilute 1 to 5% (at most) of oil in 95% of carrier oil, such as jojoba.” (You could also use almond or coconut oil.)

Children, pregnant women, elderly adults, and people with sensitive skin or severe health issues should use the lowest dilution possible. (A 1% dilution equals three drops of essential oil per ounce of carrier oil.)

Oil and water don’t mix, but you can dilute essential oils in water to make a room spray. Citrus oils (especially lemon) have disinfectant properties; lavender is calming and peppermint stimulating. White vinegar and water, mixed with a few drops of oil, such as tea tree or lemon oil, make natural household cleaners. Just don’t use it on wood or metal surfaces.

Avoid orifices and tender tissues.

“Close your eyes if you’re spraying essential oils in the room.”

If using eucalyptus to clear a stuffy nose, place a drop in a diffuser or use a ready-made inhaler. One drop of eucalyptus in a generous tablespoon of carrier oil makes a nice topical chest rub for coughs and congestion.

Never use essential oils internally except under the supervision of a clinically certified aromatherapist.

“Internal use is not the most effective way to use oils, and they (the oils) can damage the delicate mucosa lining of the mouth, esophagus, and stomach.”

Get an essential oil starter kit

With so many oils on the market, where do you begin? Caster suggests building a starter kit with an assortment of oils:

Eucalyptus globulus

This readily available oil relieves stuffy noses, chest congestion, and muscle pain.

Tea tree

A few drops of tea tree in your mop water or diluted in a spray bottle makes an effective antibacterial cleaner.


Use this antimicrobial oil to disinfect surfaces or the air as a room spray.


A good airborne disinfectant, lemon oil helps purify the air when diluted and misted about the house. Caster adds a couple of drops to a new air conditioning filter when replacing the old one.

When diluted in a carrier oil, lemon helps relieve sore, cramped muscles. Most citrus oils contain limonene which has an impressive list of therapeutic benefits.


In a room spray, rosemary promotes concentration and clarity.


A few drops of lavender in the bath or mixed with lotion or carrier oil and applied to the body helps relieve stress and anxiety. When mixed with aloe gel and carrier oil, it relieves irritated skin. You can also mix it with water for a room spray.

A little goes a long way.

Quality oils aren’t the least expensive, but they will last longer. Choose natural oils over synthetic varieties and look for oils with a batch number (not just an expiration date) on the bottle. The most reliable companies use GC/MS testing (Gas Chromatograph Mass Spectrometry). A GC/MS test identifies which aromatic oils are present and in what amounts.

“Few companies do GC/MS testing. Find one with a comprehensive source of information and recipes,” Caster says.

The Food and Drug Administration has not established standards for the aromatherapy industry. Therefore, terms like “therapeutic grade” and “medical grade” are more about marketing than efficacy.

When shopping for rare oils such as frankincense, rosewood, myrrh, or sandalwood, the label should say if it is diluted with a carrier oil. Caster advises finding a reliable company that shares its sustainability practices and history information on its website to ensure sustainable products.

If you want to purchase or learn from a qualified practitioner, “Look for someone with at least the basic certification of 400 hours of training,” Caster says.

She taps into more than 30 years of experience teaching people how to boost their immunity and protect themselves from illness through aromatherapy courses at UHealth’s Osher Center for Integrative Medicine.

“I’ve never had a cold that I can remember,” Caster says. If we look to the past, we may find solutions to modern problems such as superbugs.

Learn more about aromatherapy

The world of aromatherapy is dizzying in its depth and breadth.

Here are a few resources to start your journey:

“The research is just catching up to indigenous knowledge that has been around thousands of years. It has always been my dream to see aromatherapy validated as a science,” she says.

In the pursuit of health and happiness, she believes nature can point the way.

Nancy Moreland is a regular contributor to UMiami Health News. She has written for several major health care systems and the CDC. Her writing also appears in the Chicago Tribune and U.S. News & World Report. Medically reviewed by Karen Koffler, M.D.

Tags: Dr. Karen Koffler, essential oils, natural remedies, Osher Center for Integrative Health, well being

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