Eucalyptus Oil (1,8-Cineole)

Infants and young children

Contraindicated under 24 months because 1,8-cineole products can trigger laryngospasm. Oral use under 12 and inhalation under 3 have not been established.¹

Accidental swallowing by children

Keep the oil out of children's reach. In 109 young children admitted to a Melbourne hospital after swallowing eucalyptus oil, 28% had a depressed conscious state; the authors warn that 2 to 3 ml of pure oil can cause drowsiness and 5 ml or more significant loss of consciousness. All recovered. In a Victorian survey, 74% of young children who swallowed or may have swallowed it reached it through a home vaporiser, most often at ground level. Seizures have followed oil drops given by mouth in water or milk.^7,10,8

Children with seizures

Contraindicated in children with a history of seizures, febrile or not. Eucalyptus oil has triggered first seizures and breakthrough seizures in children with epilepsy, after swallowing, inhalation or skin use.^1,8,9

Allergy

Contraindicated with hypersensitivity to eucalyptus oil or 1,8-cineole; severe systemic allergic reactions have been reported.¹

Stomach or bowel inflammation

Use with caution in inflamed or ulcerated conditions of the gastrointestinal tract.¹

Pregnancy and breastfeeding

Safety has not been established, and the EU monograph does not recommend use during pregnancy or breastfeeding. LactMed has no entry for eucalyptus oil or cineole (its 'oil of lemon eucalyptus' entry covers a different insect-repellent product).¹

Worsening breathing

See a doctor if shortness of breath, fever or purulent sputum appears, or if cough lasts longer than a week.¹

Mostly mild stomach effects in adults; real hazards for small children and in overdose.

By mouth

Heartburn, abdominal pain, nausea, vomiting and diarrhoea are listed side effects.¹

Overdose

Doses above those recommended can cause vomiting, breathing problems, CNS depression, loss of consciousness, convulsions, ataxia and constricted pupils. In young children, swallowing a few millilitres of pure oil has caused drowsiness and, at 5 ml or more, significant loss of consciousness.^1,7

Seizures

In a prospective series of 17 children (median age 3.75 years) who had generalized seizures after eucalyptus oil drops by mouth, seizures began a median 20 minutes after exposure and none recurred over 6 to 9 months. A review of 110 published cases (49 children) found inhalation the most common route; adults were less likely than children to have prolonged or repeated seizures needing intensive care.^8,9

Skin

Contact eczema can occur; do not apply to broken or irritated skin, and wash hands to avoid eye irritation.¹

Interactions

The EU monograph reports no known drug interactions, and no interaction studies or case reports turned up in our 2026 PubMed search; LiverTox has no eucalyptus entry.¹