Eucalyptus is a fast-growing evergreen tree that is native to Australia. As an ingredient in many over-the-counter products, it is used to reduce symptoms of coughs, colds, and congestion. It also features in creams and ointments aimed at relieving muscle and joint pain.

The oil that comes from the eucalyptus tree is used as an antiseptic, a perfume, as an ingredient in cosmetics, as a flavoring, in dental preparations, and in industrial solvents.

Chinese, Indian Ayurvedic, Greek, and other European styles of medicine have incorporated it into the treatment of a range of conditions.

Eucalyptus products

There are over 400 different species of eucalyptus. Eucalyptus globulus, also known as Blue Gum, is the main source of global eucalyptus oil production. The tree can grow up to 230 feet high. The leaves are long and narrow, and the bark is blue-gray in color.

Eucalyptus leaves are steam distilled to extract the oil from the leaves of the eucalyptus tree.

The oil is a colorless liquid with a strong, sweet, woody scent. It contains 70 percent to 85 percent 1,8-cineole, known as eucalyptol. It can supplement treatment for a wide range of medical conditions.

The leaves also contain flavonoids, volatile oils, and tannins. Flavonoids are plant-based antioxidants, and tannins may help to reduce inflammation.

Properties of eucalyptus

Eucalyptol is thought to have antibacterial, anti-inflammatory, and analgesic properties.

In February 2016, researchers from Serbia found evidence supporting the antimicrobial action of eucalyptus.

They concluded that a positive interaction between E. camaldulensis essential oil and existing antibiotics could lead to the development of new treatment strategies for certain infections and that this could reduce the need for antibiotics.

A study published in Clinical Microbiology & Infection has suggested that eucalyptus oil may have antibacterial effects on pathogenic bacteria in the upper respiratory tract, including Haemophilus influenzae, responsible for a range of infections, and some strains of streptococcus.

Uses of eucalyptus

Eucalyptus is thought to have a number of medicinal properties, although not all of them have been confirmed by research.

Eucalyptus as a remedy for colds and respiratory problems

Eucalyptus features in a range of preparations to relieve symptoms of the common cold, for example, cough lozenges and inhalants.

Herbal remedies recommend using fresh leaves in a gargle to relieve a sore throat, sinusitis, and bronchitis.

Eucalyptus oil vapor appears to act as a decongestant when inhaled. It is a popular home remedy for colds and bronchitis.

It may act as an expectorant for loosening phlegm and easing congestion.

Researchers have called for further studies to clarify the possible therapeutic role of eucalyptus leaf extract in the treatment of respiratory tract infection.

Eucalyptus and dental care

The antibacterial and antimicrobial potential of eucalyptus has been harnessed for use in some mouthwash and dental preparations

In promoting dental health, eucalyptus appears to be active in fighting bacteria that cause tooth decay and periodontitis.

The use of eucalyptus extract in chewing gum may promote periodontal health, according to a study published in the Journal of Periodontology into the effect of chewing gum containing eucalyptus extract.

Other uses of eucalyptus

The University of Maryland Medical (UMM) Center describe how traditional Aboriginal medicines used eucalyptus to treat fungal infections and skin wounds. Eucalyptus tea was also administered to reduce fevers.

Towards the end of the 19th century, eucalyptus oil was used in most hospitals in England to clean urinary catheters.

Eucalyptus is an effective insect repellent and insecticide. In 1948, the United States officially registered eucalyptus oil as an insecticide and miticide, for killing mites and ticks.

The Mayo Clinic recommend oil of lemon eucalyptus as one of the most effective insect repellants in the U.S. They suggest using it for keeping mosquitoes away.

In 2012, researchers from New Delhi, in India, found that E. globulus oil was active against the larvae and pupae of the housefly. They suggested that it could be a viable option for use in eco-friendly products to control houseflies.

Eucalyptus extract may act as a pain reliever, and research indicates that the oil may have analgesic properties. In a study published in the American Journal of Physical Medicine and Rehabilitation, scientists applied Eucalyptamint on the anterior forearm skin of 10 people.

Eucalyptamint, an over-the-counter preparation with the generic name methyl salicylate topical, is used to treat muscle and joint pain linked to strains and sprains, arthritis, bruising, and backache.

The scientists concluded that “Eucalyptamint, produced significant physiologic responses that may be beneficial for pain relief and/or useful to athletes as a passive form of warm-up.”

Other conditions that eucalyptus may help with include:

• Arthritis
• A blocked nose
• Wounds and burns
• Acne
• Ulcers
• Bladder diseases
• Diabetes
• Fever
• Flu.

Eucalyptus oil may stimulate an immune system response, say findings published in BMC Immunology.

Precautions and side effects

According to the National Association for Holistic Aromatherapy (NAHA), some essential oils can be hazardous, but those that are available commercially, from reputable sources, are safe to use if handled appropriately. It is important to use “pure, authentic and genuine essential oils.”

Eucalyptus products can generally be used safely on the skin, as long as the oil is diluted. It should not be applied directly to the skin if it is undiluted. It can be diluted with a carrier oil, such as olive oil. The dilution should be between 1 percent and 5 percent eucalyptus oil to between 95 percent and 99 percent carrier oil.

Eucalyptus can produce irritation and a burning sensation. It should not be used too close to the eyes.

It is not safe to take eucalyptus oil orally because it is poisonous.

Some people may be allergic to eucalyptus. In some individuals with asthma, eucalyptus can make their condition worse. Others find that it helps to relieve their asthma symptoms.

Side effects may include:

• Diarrhea
• Nausea
• Vomiting
• Stomach upset.

Signs of eucalyptus poisoning include dizziness, feelings of suffocation and small pupils.

Eucalyptus may also interact with other medications, and it can impact the liver.

Children are more sensitive to essential oils, and care should be taken when using eucalyptus with children. Use should be avoided during pregnancy.