What is Eucalyptus Oil Used For?

Eucalyptus essential oil is an ancient remedy used historically for lung conditions and its antimicrobial benefits. The oil is derived from eucalyptus leaves that are steam distilled. Similar to the leaves, the oil has a strong, fresh scent that is quite distinct. The essential oil can be derived from different eucalyptus species, each with somewhat different effects.

The main constituent found in most eucalyptus oils is eucalyptol (1,8-cineole) with levels that can vary from 45–77% or more. Eucalyptus essential oil is commonly encountered in vapor rubs used for chest and sinus congestion. As with many folk remedies, the latest research is starting to support its historical uses. 

Research suggests that eucalyptus oil may have several potential applications:

  1. For respiratory conditions, including cough and sinus infections, chronic obstructive pulmonary disease (COPD), and asthma
  2. As an antimicrobial for some types of infections
  3. As an insect repellent, especially lemon eucalyptus oil

Eucalyptus Oil and Respiratory Conditions

When most people think of eucalyptus oil, they likely think of inhaling the oil to help with sinus and chest congestion. The main constituent in the oil, eucalyptol, has mucolytic properties. In plain terms, it helps decrease mucus. Research has shown that eucalyptol significantly reduces the expression of two genes involved with mucus production.

Beyond mucolytic effects, eucalyptol also relaxes smooth muscle present along the airways. This opens up the lungs wider, helping decrease congestion and making it easier to breathe. In combination with these effects, the oil also displays strong anti-inflammatory activity, which further helps round out its benefits for respiratory conditions. Most of the studies on its respiratory benefits have used pure eucalyptol in capsules taken orally.

Bronchitis and Sinusitis

A study on eucalyptol in patients with acute bronchitis—typically a cold with a productive cough—found clear benefits. By day four, coughing was strongly reduced in those receiving the supplement as compared to controls. The study authors attributed the benefits to eucalyptol’s mucolytic and anti-inflammatory effects.

A separate study utilizing eucalyptol for acute rhinosinusitis (sinusitis) also found significant benefits. In the study, eucalyptol was compared to a separate combination herbal product. At day four, the eucalyptol was almost twice as effective for reducing symptoms. After one week, eucalyptol continued to prove its superior efficacy. A subset of patients in the study also had bronchitis, which responded to eucalyptol as well.

Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a chronic lung condition, including both emphysema and chronic bronchitis, where it becomes progressively harder to breathe. Smoking is the most common cause, but it can occur due to other factors. Of interest, treatment with eucalyptol has been shown to help.

In a fairly large trial that lasted six months, patients with COPD were either given eucalyptol or a placebo throughout one winter. Symptom flare-ups and their severity were significantly less in those taking eucalyptol as compared to controls. Overall, the patients on eucalyptol could breathe easier, had better lung function, and improved health status—impressive results for a simple, natural product.

Asthma

Asthma is another airway disease that has been increasing in the general population. It usually presents with spasms in the airways of the lungs, in response to a trigger, making it difficult to breathe. Asthma triggers can include allergens, although non-allergic asthma is also possible. At its core, asthma is correlated with airway inflammation. While other research on natural treatments, including black seed oil and Boswellia, appears to hold some potential for reducing asthma symptoms, eucalyptol may be another option as well.

With its benefits for reducing mucus, decreasing inflammation, and relaxing smooth muscle, eucalyptus would seem to be a reasonable fit for treating asthma. And clinical trials have shown benefits. Patients who were dependent on steroids with severe asthma were able to reduce their steroid use by 36% when taking eucalyptol.

A second study tested eucalyptol in asthma patients and again found significant improvements. After six months of treatment, asthma patients on eucalyptol were able to breathe easier, had improved lung function, and had a better quality of life. Side effects were mild, were mostly gastrointestinal, and were comparable to the placebo.

Antimicrobial Effects of Eucalyptus Oil

Eucalyptus has well-known antimicrobial effects, although, again, with significant differences among eucalyptus species. In some cases, the oil has proven effective for killing fungus, bacteria, and parasites along with having potential antiviral effects.

Fungus

When compared to a standard antifungal drug, eucalyptus essential oil had similar effects against candida species found in the mouth. Based on the results, the authors concluded that diluted eucalyptus oil could be useful for helping maintain oral hygiene. For years, eucalyptus has been a common component of several different natural mouthwash-based products.

Bacteria

Due to the overuse of antibiotics, bacteria are becoming increasingly resistant to standard antimicrobial treatments. Several bacteria are well known for their resistance, including Staphylococcus aureus and Mycobacterium tuberculosis. One recent study found that eucalyptus essential oil has promising effects against most strains of methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Other studies have found similar results.

Roughly about one-quarter of people worldwide are infected with the bacterium that causes tuberculosis. A subset of these individuals will develop tuberculosis, a lung infection that can be fatal. Tuberculosis is caused by mycobacterial infections, including Mycobacterium tuberculosis. One study found eucalyptus essential oil to be a promising potential treatment that completely inhibited mycobacterial growth of multidrug-resistant mycobacteria at a 1% dilution.

Viruses

Herpes simplex virus causes cold sores and genital herpes. A study in cell culture found that eucalyptus oil had some inhibitory effects against the herpes simplex virus. While tea tree oil displayed stronger properties, eucalyptus oil still reduced viral concentrations between 58% and 75%.

And well by no means proven, early data looking at inhibition of viral enzymes critical for COVID-19 replication found promising data with eucalyptus. Of the compounds studied, computer analysis found that eucalyptol was the best substance for inhibiting one of the main enzymes needed for viral replication. As for now, clinical trials are still needed to confirm potential benefits and treatment potential.

Parasites

Echinococcus is a type of tapeworm found in animals that can infect humans. In a study on tapeworm larva from sheep, a 1% eucalyptus solution killed 100% of larva within one minute of exposure, similar to the standard drugs povidone-iodine and silver nitrate.

Head lice is another type of parasitic infection common in children. Standard treatments use a neurotoxic pesticide, permethrin, although data suggest eucalyptus oil may be an option. Lice eggs exposed to 10% eucalyptus oil for five minutes were effectively killed. A 10-minute exposure to permethrin still had a 95% hatch rate. Ginger essential oil showed similar results. When combined with eucalyptus, the combination was found to be even more effective.

Insect Repellant

Some species of eucalyptus, especially lemon eucalyptus, have shown promising results as natural insect repellents. Lemon eucalyptus essential oil has a distinct lemon-like odor. In a listing of effective insect repellents, even the Environmental Protection Agency includes lemon eucalyptus oil. Unlike normal eucalyptus, lemon eucalyptus is high in a compound called citronellal.

Studies of natural chemical compounds effective as insect repellants include common constituents from a number of essential oils, including limonene, eucalyptol, geraniol, eugenol, and citronellal. Limonene is found in citrus essential oils like orangelemon, and lime. Eucalyptol is found in eucalyptus. Geraniol is found in rose oil, palmarosa, and citronella oils. Eugenol comes primarily from cloves essential oil. And citronellal is found in lemon eucalyptus and citronella essential oils. Combinations of essential oils appear promising as a natural approach to keeping bugs at bay.

While only relevant in South and Central America, eucalyptol does attract some species of orchid bee which can sting. However, the bees are considered less dangerous than honeybees and are not found in other locations.

Safety

Many of the studies exploring the effects of eucalyptus essential oils used a purified form of eucalyptol that was taken orally. Essential oils contain potent, natural chemicals, and adulteration is not uncommon with some commercial products. Recent estimates suggest that up to 80% of commercially available essential oils may be adulterated in some way.

Oral use of essential oils should only be attempted under the recommendation of a knowledgeable healthcare provider to ensure safety and proper dosing. For medicinal use of essential oils, independent lab analysis confirming a pure product is also important.

Takeaway

The research on eucalyptus essential oil and its constituents appears to indicate promising activity for helping treat respiratory illnesses. Eucalyptus also appears to have antimicrobial effects on a broad array of organisms, including certain bacteria, fungi, and parasites along with antiviral effects. Formulations using essential oils as bug repellants also show promise, including specifically lemon eucalyptus.

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