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Eucalyptus Oil Health Benefits + Dangers & How to Use

Written by Aleksa Ristic, MS (Pharmacy) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Aleksa Ristic, MS (Pharmacy) | Last updated:

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The sharp aroma of its trees or perhaps the common household item VapoRub are probably images that first come to mind when someone mentions eucalyptus. The common belief that eucalyptus oil is an effective decongestant is true, but it can also be dangerous. Read on to learn the benefits, dangers, and how to use it for the best results.

What is Eucalyptus Oil?

Derived from Eucalyptus Globulus, eucalyptus essential oil is a liquid rich in 1,8-cineol (eucalyptol) and other beneficial components [1, 2].

At diluted concentrations, the oil is effective against infections. It can kill harmful bacteria, viruses, and fungi. It also has antioxidant and muscle-relaxing effects [3, 4, 5].

People use eucalyptus oil to reduce symptoms of colds, the flu, and other respiratory problems like asthma, bronchitis, and COPD (chronic obstructive pulmonary disease) [3].

Different species of eucalyptus differ widely regarding chemical composition, but all contain a high concentration of 1,8-cineol [6].

Eucalyptus oil can be inhaled, ingested, and put on the skin topically in highly diluted forms. Do not use a pure/undiluted solution on your skin or ingest it [3].

Snapshot

Proponents:

  • Long history of traditional use
  • Relieves nasal and chest congestion
  • May reduce pain
  • Has a relaxing effect

Skeptics:

  • Toxic in pure form and higher doses
  • Clinical research is limited
  • Can irritate the skin

Components and Mechanisms

Eucalyptus oil’s primary constituents are 1,8-cineole and α-pinene.

1,8-cineol is responsible for the thinning of mucus in the respiratory tract and has antioxidant and anti-inflammatory effects [7].

Αlpha-pinene is what gives eucalyptus oil its antimicrobial properties against bacteria and viruses [8].

They both inhibit the growth of both gram-positive and gram-negative bacteria [9].

Health Benefits of Eucalyptus Oil

Possibly Effective:

1) Nasal and Chest Congestion

Inhaling eucalyptus oil vapors can help relieve uncontrollable coughing, as the vapors provide a calming and soothing effect [10].

According to pre-clinical trials, eucalyptus oil loosens mucus buildup, which reduces the possibility of extreme allergy attacks. This is accomplished by reducing cytokine levels in the bloodstream and consequently producing less mucus buildup in the sinuses [3, 11].

Traditionally, eucalyptus oil inhalation has been used to relieve nasal congestion caused by asthma, respiratory infections, colds, and other conditions [3].

COPD

In 242 patients with chronic obstructive pulmonary disease (COPD), oral intake of eucalyptus oil helped prevent the sudden worsening of symptoms involving shortness of breath and mucus production [12].

Bronchitis

In two trials of over 500 subjects, a combination of diluted pine, lime, and eucalyptus oil extracts by oral intake helped to reduce frequent bronchitis flare-ups [13, 14].

Asthma

Eucalyptol (cineol), a constituent of eucalyptus oil, significantly reduced the use of oral steroids in 32 patients with severe asthma [15].

2) Pain

Eucalyptus oil is an efficient rubefacient, which means it mildly irritates the skin to reduce joint or muscle pain [16].

Rubbing a few drops of diluted eucalyptus oil at the temples region or forehead region can provide pain relief. The same effects can also be felt by inhaling the oil’s vapors, known as aromatherapy [17].

Along with other essential oils, it helped reduce nerve pain by combining aromatherapy and massage in 46 diabetic patients [18].

In a study of 52 knee replacement patients, inhaling eucalyptus oil after total knee replacement surgery significantly reduced pain and blood pressure, allowing for faster recovery [19].

Insufficient Evidence:

No valid clinical evidence supports the use of eucalyptus oil for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.

3) Relaxation

Inhaling eucalyptus oil can help increase concentration and also provide a calming, soothing effect.

In a study of 32 participants, a combination of diluted ethanol, eucalyptus oil, and peppermint oil rubbed near the temples and forehead area can help induce a muscle and mentally relaxing effect. The participants also had an increase in brain function [20].

Animal and Cellular Research (Lacking Evidence)

No clinical evidence supports the use of eucalyptus oil for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based studies; they should guide further investigational efforts but should not be interpreted as supportive of any health benefit.

Immunity

In animal and cell-based experiments, eucalyptus oil increased monocyte-derived macrophages in the blood, thus increasing immunity and faster recovery from infections. Macrophages are white blood cells that work by engulfing harmful organisms [21].

Microbial Infections

Eucalyptus oil combined with thermal treatment effectively prevented food spoilage caused by yeast and bacteria. This is because of the oil’s bactericidal (killing the bacteria) and bacteriostatic (prevention of bacterial reproduction) properties [22].

Eucalyptus oil can help inhibit germination and spore production of fungi, and thus has antifungal properties [23].

Side Effects & Precautions

This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.

Eucalyptus oil is likely safe in the amounts present in foods and possibly safe when used in appropriate doses, orally or topically. However, severe adverse effects may occur if one overdoses or has an allergic reaction to the substance.

Possible side effects include [24]:

  • Burning sensation in the mouth
  • Burning throat
  • Stomach pain
  • Vomiting
  • Dizziness and/or disorientation
  • Itchy hives
  • Swelling of face, hands, mouth, or throat
  • Tingling mouth or throat
  • Chest tightening
  • Breathing trouble

Warnings

For children under 2 years, eucalyptus ointments/salves or oil are not advised.

Do not give cough drops containing eucalyptus oil to children under 6 years of age.

Eucalyptus oil can slow down how fast the liver breaks down medications, so be cautious and consult physicians regarding specific drug interactions [25, 26].

Overdose

Consuming more than 1.7 mL of oil in a dose can cause severe neurological adverse effects, so make sure to not consume this oil in high amounts. Intake of 3.5 mL or more can be fatal [3].

Overdosing on this oil can lead to harmful effects on brain function, such as slurred speech. If you are directly handling this oil (in a diluted form), just 2-5 drops will suffice [3].

Never ingest eucalyptus oil orally in an undiluted form, and never rub an undiluted form of eucalyptus oil on the body.

Supplementation

Dosage

The below doses may not apply to you personally. If your doctor suggests using eucalyptus oil, work with them to find the optimal dosage according to your health condition and other factors.

The main warning associated with eucalyptus oil is to not take high doses. This oil is meant to be taken in a diluted form. If you are buying a product that contains this oil, do not exceedingly use the product. Follow the dosage recommendations. Remember, more is not better.

Never ingest eucalyptus oil orally in an undiluted form, and never rub an undiluted form of eucalyptus oil on the body. Instead, ensure that the oil has been diluted in another carrier, such as olive oil. A suggestion is 3:50 (mL) ratio in liquid form or 5-20% concentration in a salve/ointment form [3].

For inhalation or physical application of the diluted oil, stick to just 2 to 5 drops. Do not overuse [3].

Methods of Inhalation

Method One:

  1. Obtain a cup heater and a large mug.
  2. Heat them up for 8 minutes.
  3. Add 2 to 4 drops of diluted oil to the warmed mug.
  4. Take off glasses, if any, and close eyes.
  5. Inhale through mouth and nose for 3-5 minutes.

Method Two:

  1. Take a loosely woven fabric, a small wooden skewer, and a glass vial.
  2. Stuff the fabric into the vial in a cylinder shape and use a skewer to balance it.
  3. Drop the oil so that the cloth can absorb without becoming saturated.
  4. Hold vial close to lips or nostrils.
  5. Inhale for 3-5 minutes.

User Reviews

The opinions expressed in this section are solely from the users who may or may not have a medical background. SelfHacked does not endorse any specific product, service, or treatment. Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice because of something you have read on SelfHacked.

Users have used eucalyptus oil in aromatic diffusers for a refreshing ambient atmosphere in the house and helped reduce cold symptoms. Many consider it a better version of Vicks and find 5 drops or under to be an effective dosage to treat coughs and allergies.

For some, the smell is too overpowering or bitter, so it is advisable to buy a quality aroma diffuser.

About the Author

Aleksa Ristic

Aleksa Ristic

MS (Pharmacy)
Aleksa received his MS in Pharmacy from the University of Belgrade, his master thesis focusing on protein sources in plant-based diets. 
Aleksa is passionate about herbal pharmacy, nutrition, and functional medicine. He found a way to merge his two biggest passions—writing and health—and use them for noble purposes. His mission is to bridge the gap between science and everyday life, helping readers improve their health and feel better.

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