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Tasmanian blue gum

Eucalyptus globulus

Also calledEucalyptus · Eukalyptusöl (German, oil) · Eucalipto (Spanish, Italian, Portuguese) · Huile essentielle d'eucalyptus (French, oil) · Tinh dầu bạch đàn (Vietnamese, oil)

In older monographsEucalypti folium (leaf, drug name), Eucalypti aetheroleum (oil, drug name)

An Australian tree whose leaves and cineole-rich oil are used worldwide for coughs, colds and aching muscles, by inhalation, chest rubs, lozenges and capsules. The EU recognises leaf and oil only as traditional remedies; the best trials used purified 1,8-cineole, the oil's main constituent, rather than the oil itself. Swallowed neat, the oil is a poison: a few millilitres have killed adults, and it can trigger seizures and breathing problems in young children.

What it is used for

Bronchitis
Limited
In a randomised placebo-controlled trial in 242 people with acute bronchitis, 200 mg of 1,8-cineole three times daily improved a bronchitis symptom score and cough frequency after 4 days; a similar 6-month trial in 242 people with stable COPD found fewer and milder exacerbations. These trials used isolated cineole capsules, not the whole oil.^3,6,7
Sinus congestion
Limited
In a randomised placebo-controlled trial in 152 adults with acute non-purulent rhinosinusitis, 200 mg of cineole three times daily for 7 days lowered a symptom score more than placebo (3.0 vs 9.2 points from 15.6). A reference-controlled trial in 150 patients also favoured cineole. These are trials of isolated cineole, not of eucalyptus oil, and the placebo-controlled cineole trials cited here share a co-author (U. Dethlefsen).^3,8
Common cold
Limited
WHO describes a trial in which inhaled vaporised oil eased nasal congestion in 234 people with respiratory infections only during the first hour, and another in which inhaled oil did not change measured nasal airflow, though volunteers felt they breathed more freely (it stimulates cold receptors in the nose).⁴
Headache
Limited
In a small crossover study of 32 people, ethanol preparations of eucalyptus and peppermint oil rubbed on the forehead improved relaxation and cognitive measures but did not reduce sensitivity to headache pain.⁴
Cough
Traditional
The EU monographs register both the leaf (2013) and the oil (revised 2024) as traditional remedies for cough associated with colds. EMA found no controlled clinical studies of eucalyptus oil itself; trials of its main constituent, 1,8-cineole, were judged to support plausibility only.^1,2,3
Muscle pain and cramps
Traditional
The EU oil monograph registers ointments, rubs and bath additives for symptomatic relief of localised muscle pain on the basis of long use; EMA notes there are no pharmacological data for this topical use.^1,3

How it is prepared

infusion

Cut dried leaf steeped in boiling water as a tea.

EU leaf monograph (2013): 1.5–3 g in 150 ml boiling water, up to 4 times daily (4.5–12 g a day), adolescents and adults; not more than a week without medical advice.

Cough

inhalation

Oil dropped into a bowl of just-boiled water and the steam breathed in, keeping the eyes out of the steam and taking care to avoid scalds.

EU oil monograph (2024): 3–8 drops per 250 ml boiling water, 3 times daily (adolescents and adults); up to 2–4 drops for children 3–11 years; contraindicated under 2 years.

Cough · Common cold

ointment / salve

Ointment containing about 10% eucalyptus oil rubbed thinly on chest and back, or on aching muscles; not on broken or irritated skin.

EU oil monograph (2024): a thin layer 2–3 times daily, adults and children from 3 years.

Cough · Muscle pain and cramps

dry extract / capsule

Enteric or soft capsules of eucalyptus oil, taken by mouth.

EU oil monograph (2024): 100–200 mg oil, 2–5 times daily (200–600 mg a day), adolescents and adults only.

Cough

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy: Avoid
Breastfeeding: Insufficient data
Children: EU: oil contraindicated under 2 years (risk of laryngospasm) and in children with any history of seizures; oral oil not recommended under 12; leaf preparations contraindicated under 30 months. WHO advises never applying it to the face, especially the nose, of infants or young children.

Interactions with medicines

warfarinModerateA reported case of INR falling to subtherapeutic levels in a man taking eucalyptus-menthol-liquorice cough lozenges for a month.
drugs metabolised by liver enzymes (CYP3A4 and others)MinorCineole induced drug-metabolising enzymes in animals and in one volunteer study, which could weaken other drugs; in vitro it weakly inhibits CYP3A4. EMA judged clinical relevance unclear.

Interaction checker →

Do not use if

Children under 2 years (oil) or 30 months (leaf)
Children with a history of seizures
Hypersensitivity to eucalyptus or 1,8-cineole
WHO: internal use with gastrointestinal inflammation, gall-bladder disease or impaired liver function
Full hot baths with open wounds, high fever, severe infection or heart failure

Side effects

Nausea, vomiting, heartburn, diarrhoea (oral use)
Contact eczema and allergic reactions, rarely severe
Seizures after steam inhalation, nasal drops or massage with eucalyptus-oil products, reported in case series from India

Toxicity

The undiluted oil is poisonous if swallowed. Reported lethal doses are as low as 3.5–5 ml in adults; 2–10 ml in children caused depressed consciousness in a majority of 109 accidental cases. Poisoning causes vomiting, drowsiness, miosis, breathing difficulty, convulsions, coma and circulatory collapse. Ingestion by a child needs emergency care.

In the healing traditions

Western herbalism
Oleum Eucalypti / eucalyptus leaf
From the later 19th century, oil and leaf for catarrh and cough (internally, by inhalation and as chest rubs) and externally as a rubefacient for rheumatic complaints.
Köhler (1873), one of the first European eucalyptus-oil monographs; German Commission E monograph (1986)
Brazilian folk medicine
Eucalipto
Leaf tea (infusion or decoction) and steam inhalation for flu, nasal congestion, sinusitis, fever and cough in children; one of the most-cited species in a 2016 survey in Ceará.
Modern pharmacology
1,8-cineole (eucalyptol)
Purified cineole capsules (typically 100–200 mg three times daily) are sold in Germany and have been tested in acute bronchitis, rhinosinusitis, asthma and COPD; cineole is also a component of some dental root-canal sealers.

Active compounds

1,8-cineole (eucalyptol): monoterpene oxide; the Ph. Eur. requires at least 70% in the oil; mucolytic and anti-inflammatory effects in human studies
α-pinene, β-pinene, myrtenol, pinocarvone: minor monoterpenes of the oil
macrocarpals: phloroglucinol–sesquiterpene compounds of the leaf
tannins and flavonoids (rutin, quercetin, hyperoside): leaf constituents

History

Eucalyptus oil was used by Aboriginal Australians long before Europeans, but it barely appears in European materia medica before the second half of the 19th century; Köhler's 1873 monograph gathered the early evidence. Planted across the subtropics, the blue gum became one of the most widely used medicinal trees in the world, and cineole is now sold as a licensed medicine in its own right.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.