The name rings a bell for most. The sharp aroma of its trees or perhaps the common household item VapoRub are probably images that first come to mind.

The common belief that eucalyptus oil is an effective decongestant is indeed true, but it has a huge variety of less commonly known health benefits as well. Read on to learn more about eucalyptus oil and its benefits.

What is Eucalyptus Oil?

Derived from Eucalyptus Globulus, eucalyptus oil is a substance rich in an oxide called 1,8-cineol. It is a common molecule found in several essential oils like peppermint or black pepper [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].

Eucalyptus oil is most helpful in reducing uncomfortable symptoms of colds, the flu, and other respiratory problems like asthma, bronchitis, and COPD (chronic obstructive pulmonary disease) [3].

Inhaling the boiled leaf extract of Eucalyptus citriodora can help relieve inflammation, pain, and sinus congestion. Doing the same with either Eucalyptus camaldulensis or Eucalyptus urophylla can boost immunity through their antibacterial, antifungal, antioxidant, and anti-inflammatory effects [5].

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

Specifically, Eucalyptus citriodora is composed of citronellal (52.2%), citronellol (12.3%) and isoisopulegol (11.9%) [7].

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

Constituents 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 [8].

Αlpha-pinene is what gives eucalyptus oil its antimicrobial properties against bacteria and viruses and toughen the immune system [9].

1,8-cineol and alpha-pinene inhibit the growth of both gram-positive and gram-negative bacteria [10].

Health Benefits of Eucalyptus Oil

1) Eucalyptus Oil Treats Colds and Allergies

Inhaling eucalyptus oil vapors can help relieve uncontrollable coughing, as the vapors provide a calming and soothing effect [11].

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, 12].

One of the most popular uses of eucalyptus oil is to help relieve nasal or chest congestion. It helps break down stubborn mucus for easy clearing of the throat or nose [13].

For those suffering from rhinosinusitis (sinus inflammation), oral intake of eucalyptus oil provides considerable pain relief from headaches and tenderness at pressure points (trigeminal nerve). The oil also breaks down mucus, which provides relief from congestion and a perpetually runny nose [3].

For those with COPD, oral intake of eucalyptus oil can help prevent the sudden worsening of symptoms involving shortness of breath, mucus amount, and [3].

The oil can help reduce shortness of breath improving lung function [14].

Dust Mite Allergies

Pre-soaking laundry in a 0.2% eucalyptus oil detergent 30 minutes before washing and then washing in a normal laundry cycle can remove up to 97% of dust mites. Dust mite allergy is a major risk factor for asthma, so this simple procedure can significantly help prevent asthma [15].

2) Eucalyptus Oil Helps Improve Bronchitis Symptoms

Eucalyptus oil helps open bronchial air passages because it clears the airways by breaking down mucus [16].

Our lungs and nose have tiny hairs (cilia) inside of them. Eucalyptus oil can help increase nasal ciliary beat frequency. This means that mucus can be quickly cleared out from the nose and thus decrease nasal congestion [3].

This will allow for better breathing and lung activity.

A combination of diluted pine, lime, and eucalyptus oil extracts by oral intake helps to reduce frequent bronchitis flare-ups [17].

3) Eucalyptus Oil Relieves Pain

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

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 [18].

It can also be used for mild to moderate pain in aromatherapy, which is the use of natural oils for physical and mental well being [19].

Because eucalyptus oil helps relieve inflammation and pain, it also relaxes the muscles having a tension-relaxing effect on stressed muscles. It can reduce nerve pain by combining aromatherapy and massage [20].

4) Eucalyptus Oil Helps Improve Brain Activity

Eucalyptus oil also helps increase cognitive performance by relaxing muscles and tension [21].

In a study (RCT) of 62 patients the oil successfully relieved anxiety [22].

This essential oil affects the involuntary movements of the nervous system and thus brain activity, which in turn reduces pain or brings down high blood pressure [23].

5) Eucalyptus Oil Strengthens the Immune System

Eucalyptus oil increases 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, which thus help stifle infection [24].

Eucalyptus oil can help strengthen the body’s immune system after chemotherapy [24]. Chemotherapy does not just kill cancer cells, but healthy cells as well.

Eucalyptus oil activates specific cell-to-cell communication in the immune response and reduces nonspecific attacks to both foreign molecules and healthy cells [25].

Eucalyptus oil activates cells of the adaptive immune system, which recognizes and kills harmful invaders. It decreases the levels of cytokines. Therefore, it prevents infections and strengthens the immune system in chemotherapy patients [25].

6) Eucalyptus Oil Improves Emotional Well-Being

Inhaling eucalyptus oil can help increase concentration and also provide a calming, soothing effect [21].

In a study (DB-RCT) 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 mental relaxing effect. The participants also had an increase in brain function [21].

7) Eucalyptus Oil Prevents Tooth Decay

Toothpaste that contains eucalyptus oil is effective at preventing tooth decay or plaque formation because of eucalyptus’ antimicrobial properties [26].

Some dental clinics even use eucalyptus oils as a small component of sealers/solvents for root canals [27].

8) Eucalyptus Oil Can Help With Type 2 Diabetes

α-amylase breaks bonds (hydrolyzes) that exist between the many subunits of that form complex sugars, such as starch, to form disaccharides (smaller sugars of 2 subunits). α-glucosidase further breaks down these sugars into monosaccharides such as fructose or galactose, and thus further contributes to increased blood sugar levels [22].

Eucalyptus oil contains natural antioxidants that have an anti-diabetic effect by preventing the activity of the enzymes α-amylase and α-glucosidase [22].

It has water-soluble components that decrease blood sugar, which allows more glucose uptake in cells. This increases glycolysis in fat and skeletal muscle, a vital step in cellular respiration (the process that breaks down sugar into energy our bodies can use), thus reducing the amount of glucose in the blood [28].

9) Eucalyptus Oil May Improve Surgery Recovery

In a study (DB-RCT) of 52 knee replacement patients, inhaling eucalyptus oil as a vapor after total knee replacement surgery significantly reduced pain and blood pressure. This allowed for faster recovery [29].

10) Eucalyptus Oil Is Antimicrobial

Eucalyptus oil combined with thermal treatment effectively prevented food spoilage caused by yeast bacteria. This is because of the oil’s bactericidal (killing of bacteria) and bacteriostatic (prevention of bacterial reproduction) properties [30].

Eucalyptus oil can help inhibit germination and spore production of fungi, and thus has antifungal properties [31].

Diluted drops rubbed onto the skin also repel insects [32].

11) Eucalyptus Oil Helps with Necrotic Wound Treatment

An aromatherapy treatment administered with eucalyptus oil, grapefruit, and tea tree oils can help reduce the bad odor from necrotic wounds [33].

Side Effects

Adverse side effects can be seen if one overdoses or has an allergic reaction to the substance.

Possible symptoms include [34, R]:

  • 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


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 [35, 36].


The main warning associated with eucalyptus oil is to not take high doses of this oil. 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.

Consuming more than 1.7 mL of oil in a dose can cause extreme 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. 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 to 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 [3]:

  1. Obtain a cup heater and a large mug.
  2. Heat them up for 8 minutes.
  3. Add 2 to 4 drops of 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 [3]:

  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 necessary drops of eucalyptus oil that the cloth can absorb without becoming saturated.
  4. Hold vial close to lips or nostrils.
  5. Inhale for 3-5 minutes.

Drug Interactions

Eucalyptus oil can decrease blood sugar, so if you are already taking diabetic medication to lower blood sugar, it is not advisable as it may dangerously decrease blood sugar levels [35, 36].

User Reviews

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.

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