Eucalyptus (Eucalyptus globulus)is an evergreen tree native to Australia but cultivated worldwide. It was first used by the Aborigines in the dry outback—they chewed the roots, which hold a high concentration of water. They also drank eucalyptus tea as a remedy for fever. As this use spread, eucalyptus became known as Australian fever tea.
The highly concentrated oil that’s steam-distilled from the leaves of the tree has been used medicinally since at least 1788, when doctors reportedly noted the presence of the oil and began using it to treat chest problems and colic. In the late 1800s, its ability to promote sweating and clear mucus led to eucalyptus oil being prescribed for respiratory conditions including bronchitis, flu, asthma, and coughs. As word about eucalyptus oil spread, it began to be used in other ways, including as a liniment for tired, sore muscles, and to ease the pain of arthritis. Though the essential oil is still recommended today for a host of medicinal applications, its primary use remains the treatment of cough, cold, bronchitis, and symptomatic relief of colds and congestion of the upper respiratory tract.
Like most essential oils, eucalyptus oil contains many natural components. But the key one is 1,8-cineole (aka cineole and eucalyptol), the compound that’s responsible for its clean, sharp, slightly medicinal smell as well as its medicinal value. According to a 2010 review, eucalyptol has been shown to have strong antibacterial, antiviral, and anti-fungal action, which may explain its traditional use as a treatment for respiratory ailments.
Few of the proposed benefits for eucalyptus oil have strong science behind them, according to the Natural Medicines Comprehensive Database (NMCD), which rates effectiveness based on scientific evidence. Though promising, most evidence is considered preliminary. Here’s a rundown on what’s known so far about how eucalyptus oil can benefit health.
Cold and Respiratory Relief
You may know eucalyptus oil best from products like Vicks VapoRub, where it acts to clear your airways. At least one study published in 2012 found some benefit for a vapour rub (VR) containing camphor, menthol, and eucalyptus oil compared to a petroleum placebo when used on children at nighttime. Between treatment groups, researchers detected significant differences in improvement in cough, congestion, and sleep difficulty, with the VR group consistently scoring the best over placebo for cough severity, child and parent sleep difficulty, and combined symptom score. There was no effect on runny nose, and VR-treated children experienced some skin redness and burning.
Eucalyptus oil is often used in the form of steam inhalation to help ease cold symptoms, though studies are needed to confirm the value of this use. When inhaled into the respiratory system, it’s believed to reduce the muscle spasms that can narrow your airway and make it difficult to breathe. It’s also said to be a gentle expectorant and to promote drainage from congested sinuses.
In traditional herbal medicine, eucalyptus tea or oil is often used internally as well as externally over the chest. Both uses are approved by the German Commission E, the expert panel that evaluates herbal medicine, to treat bronchitis. This condition is a common inflammation of the lining of the tubes that carry air to and from your lungs that often develops from a cold. A double-blind, placebo-controlled study published in the journal Cough in 2013 confirmed that people with bronchitis may benefit from treatment with oral cineole. Over a period of 10 days, 242 patients received either 200 milligrams of cineole three times a day or a placebo. After four days of treatment, it was notable that the group treated with cineole showed significantly more improvement in symptoms of acute bronchitis, especially the frequency of coughing fits.
Cineole may help speed the healing of acute sinusitis, which often starts as a cold and then turns into a bacterial infection. In a 2004 double-blind study of 150 people with acute sinusitis that did not require treatment with antibiotics, those given 200 milligrams of cineole orally three times a day recovered significantly faster than those given a placebo.
Early research shows that eucalyptol might be able to break up mucus in people with asthma. While some people with severe asthma have been able to lower their dosage of steroid medications by taking eucalyptol, you shouldn’t try this without your healthcare provider’s advice and monitoring.
Topical ointments containing the oil have been used in traditional Aboriginal medicine to support wound healing, a use that modern science has investigated. A study from 2012 looked at the antimicrobial activity of eucalyptus oil against two pathogens, S. aureus, which is mainly responsible for post-operative wound infection, toxic shock syndrome, and food poisoning, and E. coli, which is responsible for urinary tract infections. Researchers found that the oil had activity against both bacteria. This type of antibacterial action may make eucalyptus oil an effective treatment for minor cuts and wounds, says herbal expert Michael Castleman, the author of “The New Healing Herbs.” He suggests applying a drop or two of eucalyptus oil to a clean wound.
Like many essential oils, eucalyptus oil is being investigated for its use as a pain reliever. In a 2013 study, inhalation of eucalyptus oil for 30 minutes on three consecutive days following knee replacement surgery was effective in decreasing patients’ pain and blood pressure.
A eucalyptus-based ointment was found to increase circulation when applied to the forearms of participants in a small double-blind study published in 1991, which suggests that eucalyptus may temporarily ease minor muscle soreness when applied topically. Like menthol and wintergreen, eucalyptus is considered a counterirritant. It works by irritating the skin where it’s applied, causing the skin to feel hot or cold.
Early research published in the Journal of Periodontology shows that chewing gum containing 0.3 percent to 0.6 percent eucalyptus extract can reduce dental plaque and gingivitis, and improve bad breath in some people. Some dentists recommend diluting one drop of eucalyptus oil with olive or coconut oil and swishing in your mouth or applying one drop to your toothpaste before brushing.
Possible Side Effects
Eucalyptol, the active chemical found in eucalyptus oil, is possibly safe when taken by mouth for up to 12 weeks, according to NMCD. Eucalyptus oil is likely unsafe when taken by mouth without first being diluted.
Eucalyptus oil should not be applied directly to the skin. Using it “neat” can cause severe irritation. To dilute an essential oil, a good rule of thumb is to add 12 drops of the oil to each fluid ounce of carrier oil like almond, apricot kernel, or avocado oil, or lotion.
Not enough is known about using eucalyptus oil during pregnancy and lactation, so don’t use it without medical advice. Eucalyptus oil is also likely unsafe for children and should not be taken by mouth or applied to the skin.1
If you have a medical condition, consult a qualified practitioner before using essential oils. Certain essential oils shouldn’t be used by people with health conditions. For instance, people with liver or kidney disease should only use essential oils under the guidance of a qualified practitioner. Once absorbed into the bloodstream, essential oils are eventually cleared from your body by the liver and kidneys. Using essential oils excessively may injure these organs.
Consult a qualified practitioner if you take any medication, because essential oils may interact with certain medications. For instance, early research suggests eucalyptus might lower blood sugar, so blood sugar levels need to be monitored closely if you take medications for diabetes. Since eucalyptus might affect blood sugar levels, there’s a concern it might make blood sugar control difficult during and after surgery. Stop using eucalyptus at least two weeks before a scheduled surgery.
If you’re considering the use of essential oils for a health condition, make sure to consult your physician first. Self-treating a condition and avoiding or delaying standard care may have serious consequences.
Dosage and Preparation
Small doses of eucalyptus oil (0.05 to 0.2 milliliters a day) can be taken internally by adults. Always dilute the oil in warm water before consuming it. To prepare an infusion, boil one to two teaspoons of the chopped leaves in a cup of water and steep for 10 minutes. You can drink up to two cups a day. To make an ointment, add a few drops to petroleum jelly and apply as a thick layer up to three times a day.
If using a commercial product, be sure to follow directions on the label.
Be aware that eucalyptus oil is highly poisonous, and taking 3.5 milliliters (slightly less than a teaspoon) of undiluted oil has proven fatal. Signs of eucalyptus poisoning might include stomach pain and burning, dizziness, muscle weakness, small eye pupils, feelings of suffocation, and some others. Eucalyptus oil can also cause nausea, vomiting, and diarrhea.
To make a eucalyptus inhalant, add a few drops of eucalyptus oil or a handful of leaves to hot water or a vaporizer and deeply inhale the steam vapor for five to 10 minutes (take care not to burn yourself).
You can also use eucalyptus oil in a warm bath or shower. To do so, add two to three drops of the essential oil to your bath just before getting in. If you’re taking a shower, place two to three drops of the essential oil onto a wet washcloth. When the warm water of the shower heats the washcloth, the vaporized oil is released.
The National Center for Complementary and Integrative Health advise that research into the effects of topically applied tea tree oil in people is limited.
However, the oil may be useful for a number of skin complaints.
Acne is the most common skin condition. It affects up to 50 million Americans at any one time.
One study found a significant difference between tea tree oil gel and a placebo in treating acne.
Participants treated with tea tree oil experienced improvement in both total acne count and the severity of the acne.
This builds on earlier research which compared 5 percent tea tree oil gel with 5 percent benzoyl peroxide lotion in treating cases of mild to moderate acne.
Both treatments significantly reduced lesions, although the tea tree oil worked more slowly. Those using the tea tree oil experienced fewer side effects.
6. Athlete’s foot
Symptoms of athlete’s foot, or tinea pedis, were reduced through topical application of a tea tree oil cream, according to the study.
A 10 percent tea tree oil cream appeared to reduce the symptoms as effectively as 1 percent tolnaftate, an antifungal medication. However, the tea tree oil was no more effective than a placebo in achieving a total cure.
More recent research compared higher concentrations of tea tree oil on athlete’s foot with a placebo.
A marked improvement in symptoms was seen in 68 percent of people who used a 50 percent tea tree oil application, with 64 percent achieving total cure. This was over double the improvement seen in the placebo group.
7. Contact dermatitis
Contact dermatitis is a form of eczema caused by contact with an irritant or allergen. Several treatments for contact dermatitis were compared, including tea tree oil, zinc oxide, and clobetasone butyrate.
Results suggest that tea tree oil was more effective in suppressing allergic contact dermatitis than other treatments. However, it did not have an effect on irritant contact dermatitis.
Keep in mind that tea tree oil itself may induce allergic contact dermatitis in some people.
8. Dandruff and Cradle Cap
Mild to moderate dandruff related to the yeast Pityrosporum ovale may be treated with 5 percent tea tree oil, according to one study.
People with dandruff who used a 5 percent tea tree oil shampoo daily for 4 weeks showed significant improvements in overall severity, as well as in the levels of itchiness and greasiness, when compared with a placebo.
Participants experienced no negative effects.
Another study found tea tree oil shampoo effective for treating children with cradle cap.
It is possible to be allergic to tea tree oil. To check for a reaction, put a little shampoo on the infant’s forearm, and rinse. If no reaction occurs in 24 to 48 hours it should be safe to use.
9. Head lice
Head lice are becoming more resistant to medical treatments, so experts are increasingly considering essential oils as alternatives.
Research compared tea tree oil and nerolidol – a natural compound found in some essential oils – in the treatment of head lice. The tea tree oil was more effective at killing the lice, eradicating 100 percent after 30 minutes. On the other hand, nerolidol was more effective at killing the eggs.
A combination of both substances, at a ratio of 1 part to 2, worked best to destroy both the lice and the eggs.
Other research has found that a combination of tea tree oil and lavender oil was effective at “suffocating.”
10. Nail fungus
Fungal infections are a common cause of nail abnormalities. They can be difficult to cure.
One study compared the effects of a cream comprising both 5 percent tea tree oil and 2 percent butenafine hydrochloride (a synthetic antifungal) with a placebo.
After 16 weeks, the nail fungus was cured in 80 percent of people. None of the cases in the placebo group was cured.
Another study showed tea tree oil effective in eliminating nail fungus in the laboratory.
However, this research does not definitely show that the tea tree oil component of the cream is responsible for the improvements experienced, so further research s needed.
11. Oral health
A gel containing tea tree oil may be beneficial for those with chronic gingivitis, an inflammatory gum condition.
Study participants who used tea tree oil gel experienced a significant reduction in bleeding and inflammation when compared with a placebo or a chlorhexidine antiseptic gel.
Other research indicates that a type of bacteria associated withbad breathmay be treated with tea tree oil and alpha-bisabolol, the active component in chamomile.
The amount and timing of tea tree oil dosage depend on several factors, including the condition requiring treatment, its severity, and the concentration of the tea tree oil.
Five possible uses of tea tree oil
Tea tree oil has many applications. Some suggestions include:
Wound dressing. Place a few drops of oil onto fresh wound dressing to kill bacteria and reduce inflammation.
Homemade mouthwash. Add 2 drops of tea tree oil to a cup of water and use as mouthwash. Do not swallow as tea tree oil is toxic if taken internally.
Natural dandruff remedy. Mix a few drops of tea tree oil into regular shampoo and wash hair as normal.
Acne treatment. Add 4 drops of tea tree oil to a half cup of water. Apply to the face with a cotton pad once daily.
Household cleaner. Mix 20 drops of tea tree oil with a cup of water and a half cup of white vinegar. Pour the mixture into a spray bottle and use as an all-purpose antimicrobial cleaner.