Coronaviruses and Essential Oils

A common question we've been asked lately:

Can essential oils treat the coronavirus (COVID-19)?

Short answer:

No. Essential oils, at least as we can currently evaluate them, are not an effective prevention or treatment strategy for COVID-19.

However, current scientific evidence does support some beneficial antiviral impact using specific essential oils in cleaning solution on surfaces (and land areas), diffused into the air, and possibly inhaled. Humans have also been using essential oil blends for thousands of years for these types of illnesses. There's likely some wisdom in that historical use.

Essential Oils Can Be Part of a Holistic Approach for COVID-19

No surprise, we like to think holistically about treatment for any health condition. Blends of essential oils with ingredients such as spruce and eucalyptus may offer beneficial impact for a wide range of germs. Problem is, there's just not enough clear data to support which oils work for which viruses and how they should be delivered/used optimally. (Please see below the "longer answer" for more details on the state of the science.)  

Absent of clear evidence, there are primary practices that have strong scientific support and that should be focused on first.

Prioritize the primary practices! 

Secondary practices that may further enhance outcomes and that are safe can then be added.

Secondary practices are often those that also feel good and that support mood and calm the stress response. We like those too!

So, start with the primary practices. The WHO lays out the primary practices that you should focus on first: 

1. Wash hands. Twenty full seconds of scrub, scrub, scrubbing with soap and water. It's wise to do the same with the surfaces and items you encounter and keep them clean (disinfect your phone!).
2. Stay away from coughers and sneezers. Six feet of space from a sick person is a good distance.
3. Hands off your face. If you need to touch your face, do #1 immediately before. 
4. Cover your cough or sneeze with a tissue or your bent elbow. AKA don't spread germs!
5. Watch Netflix if you're sick. Yes, stay home and rest. If you have a fever, cough, difficulty breathing, or other concerning symptoms, seek medical attention and call in advance of coming in. 

Secondary Practices:

1. Don't panic. Your immune system doesn't function well amidst anxiety. Practice self-care that nourishes you. Try diving into a book series you've been thinking about, meditating, listening to music, going for walks, etc. 
2. Eat healthy. Your system needs good fuel to thrive and combat illness. Try the Resilient Diet for optimal fuel.
3. Sleep! Sleep is the silver bullet for most things. Get good sleep to support your immune system. 
4. Get fresh air. Go outside, preferably for walks, as often as you can. Follow the primary practices from the WHO as you stroll.
5. Create a healthy space. In addition to disinfecting surfaces, diffusing essential oils with antiviral potential may help keep your space more germ free. Try blends of spruce and eucalyptus.

Longer answer:

Researchers interested in the use of essential oils to treat viral and bacterial infections have a lot of work to tackle. Current research is of poor quality and little is understood about how humans might use essential oils most effectively to tackle prevention, treatment, and recovery from these types of illnesses. At this time, there is some evidence for use of essential oils to care for viruses with topical application, diffusion into one's personal environment, closer-range diffusion or inhalation, and as a cleaning agent for surfaces or land areas. Note that the evidence is still weak and that use of oils should be considered only after taking far more effective preventative measures (see these measures in the "Holistic Approach" section further below). 

Carson & Hammer (2011; access here) summarized much of the essential oil antiviral research and noted, 

"The majority of in vitro studies have been conducted using the enveloped influenza or herpes simplex viruses 1 or 2 (HSV-1 or -2). Essential oils from Artemisia glabella, Cynanchum stauntonii, Houttuynia cordata, Oenanthe crocata, Origanum acutidens, Salvia limbata, and S. sclarea and the component cinnamaldehyde have been tested against influenza viruses.

Oils from tea tree and eucalyptus, anise (Illicium verum), hyssop (Hyssopus officinalis), thyme (Thymus vulgaris), ginger (Zingiber officinale), chamomile (Matricaria recutita) and sandalwood (S. album), A. aborescens, H. cordata , L. scoparium, Melaleuca ericifolia, M. leucadendron and M. armillaris, Melissa officinalis, M. piperita, O. crocata, Salvia fructicosa, S. limbata and S. sclarea, S. album, Santolina insularis, a range of South American plants including Aloysia, Artemisia and Lippia spp., and the components eugenol  and isoborneol have been tested against HSV-1 and/or -2. Minami et al. tested oils from Cupressus sempervirens (cypress), Juniperus communis (juniper), M. alternifolia (tea tree), Ocimum basilicum album (tropical basil), M. piperita (peppermint), Origanum majorana (marjoram), Eucalyptus globulus (eucalyptus), Ravensara aromatica (ravensara), Lavandula latifolia (lavender), Citrus limonum (lemon), Rosmarinus officinalis (rosemary) and Cymbopogon citrates (lemongrass) against HSV-1.

Most of these essential oils have been evaluated by measuring the inhibition of plaque formation in tissue cultures of appropriate host cells, a widely used method of measuring antiviral activity. In general, the concentration of oils or components that reduced plaque formation by 50% ranged from 0.000 06 to 1%. Often the concentrations of oil that inhibit plaque formation are only marginally lower than the concentrations that prove cytotoxic to the tissue-culture cells, resulting in a comparatively low therapeutic index.

In some instances, no antiviral activity is seen at concentrations that are noncytotoxic to the host cell line, such as when Juniperus oxycedrus ssp. badia oil was tested against two strains of human immunodeficiency virus (HIV). Nevertheless, interest in the potential of oils as antiviral agents persists, particularly for topical use such as hand and skin antisepsis.

Apart from the more widely tested influenza virus and HSV... the viral aetiological agent of severe acute respiratory syndrome, a novel coronavirus [236], have also been tested against a range of oils and components with similar results.

With regard to the mechanism of antiviral action, in most cases where antiviral effects have been assessed before and after host-cell adsorption, the antiviral effect has occurred largely upon treatment of virus particles with oil prior to their adsorption or addition to cell monolayers. This suggests a direct effect of oil on free virus particles rather than an intracellular antiviral effect. The site of action has not been identified but most of the viruses tested have been enveloped viruses, with the exception of adenovirus, poliovirus, and tobacco mosaic virus. Viral envelopes are typically derived from the membrane of the host cell and have a phospholipid bilayer structure. Since many essential oils have the capacity to disrupt biological membranes, it follows that viral envelopes may also be disrupted by essential oils, a contention supported by electron micrographs of HSV-1 after treatment with oregano or clove oils showing envelope disruption.

In contrast to the growing body of in vitro data, there are very few reports of in vivo activity. Black-seed oil (Nigella sativa) was tested against murine cytomegalovirus and C. stauntonii oil, Heracleum spp. oils and cinnamaldehyde were tested against influenza in mouse models. Studies in humans are also very limited. Teatree oil has been evaluated for the treatment of herpes labialis in a small pilot study with promising results, suggesting a reduction in the time to complete healing with the use of tea-tree-oil ointment compared to control, and B. citriodora essential oil was trialed in the treatment of molluscum contagiosum, a cutaneous viral infection caused by the virus of the same name, in which lesions were resolved completely in 5 of 16 participants, reduced in number by more than 90% in 4 of 16 and reduced in number less than 90% in 6 of 16. One participant was lost to follow-up. In the vehicle placebo group 0 of 15 met the criteria of a 90% reduction in lesion number while 12 of 15 had no change or an increase in lesion number."