What is Eucalyptus?
Blue Gum (Eucalyptus globulus)
Eucalyptus globulus is also known as gum tree, fever tree, southern or Tasmanian blue gum, and stringy bark. It is native to Tasmania and Australia and is the principal source of eucalyptus essential oil. The oil is sometimes referred to as nilgiri oil.
The tree was first discovered in 1792 by French botanist Jacques de Labillardière during the d'Entrecasteaux expedition. He later wrote about the discovery in 1799, and this is the first known description of the tree published. 
This is an incredible tree that grows rapidly and can reach towering heights of almost 300 feet. Blueish-green leaves grace the younger trees, while the older ones have long and narrow sickle-shaped leaves that are a silvery green.
The oil of E. globulus was first distilled in the 1850s. It is produced through steam distillation of young twigs and fresh or slightly dried leaves. Blue gum oil is clear to light yellow and has a strong camphorous scent that is fresh and green with a slightly sweet, woody undertone.
Blue gum oil blends well with basil (Ocimum basilicum), black pepper (Piper nigrum), cypress (Cupressus sempervirens), frankincense (Boswellia carterii), geranium (Pelargonium graveolens), rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris), and more.
Eucalyptus Lemon (Eucalyptus citriodora)
The lemon-scented eucalyptus, E. citriodora, is also known as citron-scented gum, boabo, scented gum tree, and spotted gum. The botanical name may be listed as Corymbia citriodora.
The tree itself is smaller than E. globulus, yet can grow to 100 feet or more. The smooth albeit dimpled trunk can range from white to copper or even pink in spots, and the leaves are thin. The fluffy white flowers hold glossy black seeds.
Steam distillation of the leaves and twigs creates a colorless or yellow-tinged liquid that smells of balsam and citrus.
Lemon eucalyptus blends well with cedarwood atlas (Cedrus atlantica), elemi (Canarium luzonicum), E. dives, E. citriodora, lavender (Lavandula angustifolia), peppermint (Mentha piperita), ravensara (Ravensara aromatica), and vetiver (Vetiveria zizanioides), among others.
Eucalyptus Peppermint (Eucalyptus dives)
The broad-leaf peppermint (E.dives) is also known as the blue peppermint, eucalyptus mint, or menthol-scented gum. It is shorter than blue and lemon gum trees at 60 feet.
The gray bark is fibrous and furrowed. The spreading branches hold thick, broad, fragrant leaves and small flowers.
There are two species known in Australia as peppermint eucalyptus, and while both have been used for their oil, E. dives is the most commonly utilized for aromatherapeutic purposes.
The other, E. piperita, was the first known eucalyptus to be distilled. In 'Journal of a Voyage to New South Wales,' Dr. John White, the 'surgeon to the first fleet,' writes of personally distilling it in 1788. He referred to it as 'Sydney Peppermint.' 
E. dives is unique in that it can both flower and fruit while very young and only six feet tall. Native Aborigines often use it medicinally, as well as for containers, food, and tools. 
The essential oil produced through steam distillation of the leaves and twigs is yellow and thin, smelling of balsam and wood with a pronounced peppermint aroma.
Some of the oils that go well with E. dives are bay laurel (Laurus nobilis), bergamot (Citrus bergamia), German chamomile (Matricaria recutita), sweet fennel (Foeniculum vulgare var. dulce), lavandin (Lavandula x intermedia), and yuzu (Citrus junos).
Eucalyptus radiata (E. radiata)
This tree grows to about the same height as E. citriodora at 100 feet. The two can still be easily differentiated as the bark on E. radiata is almost black lower on the trunk and smooth nearing the top. Numerous flowers punctuate thin, dull-green leaves.
This species of eucalyptus flourishes in New South Wales along creeks and rivers along the mountainous coastal regions. This tree has more oil glands than other species of eucalyptus, and the first recorded distillation was in 1898. 
Also referred to as Eucalyptus australiana, the essential oil is thin, colorless to light yellow, and boasts a slightly woody scent and a lighter eucalyptus aroma than other volatiles of its kind. It is steam distilled from the same parts of the tree, the leaves and twigs.
As E. radiata essential oil is not as harsh as E, globulus, it is often preferred in aromatherapy work. It blends well with all of the oils listed for the others, as well as Roman chamomile (Anthemis nobilis), grapefruit (Citrus paradisi), other eucalyptus, and many others.
Eucalyptus Essential Oil Uses
Eucalyptus trees have a long history in Australia. They have grown there for millions of years, and provide many uses for their environment. Koala bears dine on them, and the Aborigines have always counted on the eucalyptus tree for many uses, including medicine.
They are incredibly robust trees and can survive fires. Their oil is so abundant it fuels the flames, and they recover quickly once it's gone, as long as termites don't destroy them in their weakened state. If that happens, their hollowed trunks become home to many wild animals. 
One of the first known commercial uses of eucalyptus oil was as fuel in Kyneton, Victoria as a substitute for coal-produced gas. However retail sales of the oil was started by Joseph Bosisto, a Victorian pharmacist and Australian pioneer. Exports to England began in 1865.
Bosisto created a massive marketing campaign touting the wonders of eucalyptus oil and its uses for "arts, manufactures, medicine and sanitary purposes." During the influenza crisis of 1918-1919, 2-3 drops were placed on a sugar cube and taken by mouth as treatment. 
While it is not recommended to take essential oils in this manner unless under the care of a doctor and aromatherapist trained explicitly in internal use, there are still plenty of ways to use this helpful oil at home. You can also purchase many eucalyptus products in stores these days.
E. radiata and E. citriodora can be used in most instances by anyone, and there are no contraindications known. E. globulus should not be used by the convalescing or elderly. It should also not be used by those pregnant or nursing.
E. dives also should not be used by pregnant or nursing women. It may also cause reactions on those with sensitive skin. It is best to always perform a skin patch test when using any new oil.
There have also been numerous cases of eucalyptus poisoning. Many of these were in children and due to ingestion, but some poisoning cases occurred with topical use. Eucalyptus has also been known to cause respiratory and central nervous system depression in children.
Therefore, do not use any form of eucalyptus on babies or young children. E. radiata and E. citriodora can start being used once the child reaches the age of nine.
Eucalyptus oils are antibacterial and can be helpful in combating acne. With eucalyptus being a rather strong-smelling oil, you will want to use E. radiata, even though they are all antimicrobial.
The following recipe may sound strange because it is oil-based, but if you think back to seventh-grade chemistry, like dissolves like. This is the basic explanation of how solvents work. So here, we are going to use oil to dissolve the oil on the face, without drying it out.
- 2 tsp Tamanu (Calophyllum inophyllum)
- 1 tsp Sesame Seed oil (Sesamum indicum)
- 2 drops Eucalyptus (E. radiata)
- 2 drops Palmarosa (Cymbopogon martinii)
- 1 drop Geranium (Pelargonium graveolens)
These oils are all antibacterial so are beneficial for acne-prone, problem skin. Those with sensitive skin should be careful and test this first, as some of the oils, including sesame, can cause sensitivity or an allergic reaction.
Blend all of the oils in a dark glass bottle. To use, put a small amount on your fingers and gently massage all over the face for a minute or two. Leave on for a few minutes.
Next, run hot water over a clean wash rag. Place this over your face until it cools. This opens up your pores. Gently wipe any excess oil off. A thin amount of remaining oil is good and will help maintain moisture.
You can use this method whenever you clean your face. However, I would recommend only using the essential oils for a couple of days, then take a day off and just use the mix of tamanu and sesame or another oil blend.
You may find your skin gets worse for a brief period before beginning to get better. This is normal. If you react poorly to the sesame oil, you can use other carrier oils like coconut (Cocos nucifera), olive (Olea europaea), camelina (Camelina sativa), etc.
Many essential oils can be used for repelling insects. Eucalyptus is one of those oils. Use E. globulus or E. citriodora on cotton pads or in sprays to repel moths and keep them away from clothes.
You can also use any of the eucalyptus varieties to repel flies, although you would likely have better luck with the stronger ones as opposed to the softer E. radiata. Other oils you can include in fly repellent blends are:
- Basil (Ocimum basilicum)
- Citronella (Cymbopogon martinii)
- May chang (Litsea cubeba)
- Garlic (Allium sativum)
- Lemongrass (Cymbopogon citratus / flexuosus)
- Peppermint (Mentha piperita)
Eucalyptus can also help keep mice away as well, and putting it in a spray can help reduce mite infestations in gardens. If you are ever in doubt as to what to use to keep whatever insect away, E. citriodora is always a good bet.
Massage Treatments for Pain
Eucalyptus is analgesic and can be included in liniments for powerful pain relief. To make a simple liniment, add one teaspoon of the essential oil to a half-cup of vodka. Shake well and rub into the painful area.
It works well in blends for aching muscles made with oils as well. The next time you have a muscle strain or just all-around aches from over-exertion, try the following:
- 5 drops Marjoram, sweet (Origanum majorana)
- 5 drops Plai (Zingiber cassumunar)
- 4 drops Eucalyptus (E. radiata)
- 3 drops Black Pepper (Piper nigrum)
- 3 drops Peppermint (Mentha piperita)
Blend all oils in a dark glass bottle. To use, add 2-3 drops to a teaspoon of carrier oil and rub in.
Good choices for a carrier oil for this are St. John's Wort (Hypericum perforatum) due to its analgesic properties. Making a mix of five parts hemp (Cannabis sativa) oil to one part arnica (Arnica montana) macerated oil is a good combination for sore muscles as well.
The human mouth carries over 500 bacteria, and those are only the ones that have been identified.  While many of these are good bacteria that fight off the bad ones that make their way in, there are plenty that are still unwelcome.
Most essential oils are antimicrobial, and many are antibacterial. Eucalyptus is one of them, and you can make homemade mouthwash to keep the germs at bay.
- ½ cup Water, distilled
- 2 teaspoons Baking soda
- 2 drops Peppermint (Mentha piperita)
- 1 drop Eucalyptus (E. spp)
- 1 drop Tea Tree oil (Melaleuca alternifolia)
Put all your ingredients in a bottle or jar, close and shake. Use as you would regular mouthwash. You can easily mix this up with other oils as you like, such as cardamom (Elettaria cardamomum), clove (Syzygium aromaticum), and spearmint (Mentha spicata).
Never swallow mouthwash. Swish it around in your mouth for a minute or two, gargle, then spit it out.
Steam inhalation is an excellent way to open the pores of your face, clear out your sinuses, and help with lung congestion. Eucalyptus oil can help with all of those issues and is good for both oily and problematic skin as well as respiratory infections.
Try adding the oils to your shower to create a home-based sauna.
Eucalyptus Essential Oil Benefits
Eucalypti were once considered 'fever' trees, and many publications pointed to the lack of fevers in Australia to support this claim. Its medicinal benefits were utilized during World War I as well as the influenza epidemic that followed. 
Using eucalyptus oil may not save you from ever getting a fever, but it can help reduce the germs that could cause them. Here are just a handful of the benefits you can gain from the eucalypti oils.
We all have those times when concentration eludes us, and this usually occurs when we need to concentrate the most. Essential oils can help us focus our minds and get the task at hand done.
Lemon-scented eucalyptus is one of the oils that can provide this benefit. You can use it on its own, or make a blend with any of the following volatiles:
- Basil (Ocimum basilicum)
- Bergamot (Citrus bergamia)
- Cardamom (Elettaria cardamomum)
- Cedarwood atlas (Cedrus atlantica)
- Grapefruit (Citrus paradisi)
- Frankincense (Boswellia carterii)
- Lemon (Citrus limon)
- Peppermint (Mentha piperita)
- Rosemary (Rosmarinus officinalis)
Calms Respiratory Distress
Anytime a respiratory issue comes up, eucalyptus is the first oil many people think of, and for good reason. All of the eucalypti mentioned above, except for E. citriodora, are good choices for infections of the respiratory system.
That being said, eucalyptus radiata is the preferred oil to use, especially for seniors or those who are pregnant, nursing, or are convalescing. The reason it is such a good choice is that it is:
- Antiphlogistic (reduces fever / inflammation)
- Anti-putrescent (fights putrefaction)
- Antitussive (relieves cough)
- Febrifuge (anti-fever)
You can use it in diffuser blends, for facial steaming, in personal inhalers, and to make decongestant oils and ointments to rub on the chest and back area to help clear sinuses and open the airways.
Help Reduce Fatigue
Chronic fatigue syndrome is a medically baffling condition that causes the sufferer muscle pain, extreme fatigue that will not go away, sensitivity, headaches, insomnia, inability to concentrate, and many more symptoms.
There is no cure and doctors have not found the cause. Essential oils will not heal someone suffering, but they can help manage some of the symptoms. Both E. radiata and E. citriodora can help, along with many others. Look for oils that affect your particular side effect.
Healing for Skin Conditions
You can use eucalyptus oils to help heal many types of skin issues, including nail infections and hair problems like dandruff. You can turn to the eucalypti oils for:
- Abrasions, cuts, and wounds
- Athlete's foot
- Bites and Stings
- Cold sores
- Head lice
Again for any of these, you can turn to eucalyptus radiata. Lemon-scented can help with some of the issues as well. If you are out of those, blue gum will work, but it will be strong, and the warnings should be heeded.
Eucalyptus and tea tree oil are excellent choices to blend together for their skin-healing attributes.
Supports the Immune System
Many oils support the immune system, and eucalyptus oils are no different. Being antiviral and antibacterial, both E. radiata and E. globulus are potent immunity boosters. Blue gum has even been found to boost the immune response in broiler chickens. 
Use them in blends meant to combat illness-causing bugs and germs.
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Eucalyptus Essential Oil Research, Facts, and Studies
Various forms of eucalyptus oil have been widely studied. As of this writing, there are 544 results for the term on PubMed alone. 
In a study from The International Journal of Nanomedicine from 2017, researchers found that eucalyptus oil mixed with olive oil has a synergistic effect in the treatment of wounds. 
If you have ever had the misfortune of having to deal with head lice infestations, you have likely come across products containing eucalyptus. In a study from 2017 published in The Australian Journal of Dermatology, scientists set out to determine the efficacy of this treatment.
They tested a treatment containing Australian eucalyptus oil and lemon tea tree (Leptospermum petersonii) on children and adults in a trial. They also examined the solution in vitro. The treatment was compared to a pyrethrins and piperonyl butoxide (P/PB) mousse.
The researchers found that the EO treatment was more than twice as effective as the standard chemical mousse application. There was also minimum side effects, making the essential oil treatment an effective alternative to chemical solutions. 
There are many different types of eucalypti in Australia. The four in this article are the more popular ones you will see as oils.
There are countless ways to use eucalyptus, and those herein are just a fraction of all that can be done. It has been utilized for centuries by Australian Aborigines, and science is finally catching up to prove their anecdotal evidence.
You will want to pay particular attention to the botanical name of the eucalyptus you buy, so you know how to use it and what to use it for. Always be sure to use the correct type for the particular person, as stronger oils can be dangerous for some people, including children.
- Worwood, Valerie; The Complete Book of Essential Oils and Aromatherapy, pg 586
- Worwood, Valerie; The Complete Book of Essential Oils and Aromatherapy, pg 587