Health Benefits of Eucalyptus

Eucalyptus (Eucalyptus spp.) is a tree native to Australia and Tasmania. Eucalyptus leaves are used to make eucalyptus oil, which is added to food, pharmaceutical, and cosmetic products.

Eucalyptus oil has Generally Recognized As Safe (GRAS) status and is approved by the U.S. Food and Drug Administration (FDA) for its intended food uses.

Eucalyptus oil has been used in food products to increase shelf life, inhibit microbial growth, and improve taste. Pharmaceutical products such as lozenges, cough syrups, and mouthwashes can contain eucalyptus oil. Eucalyptus leaves are also used in tea, especially in India and South Africa, to relieve fever, colds, and coughs. 

While eucalyptus oil may affect microbial infections, inflammation, pain management, and dental health, evidence of its effects on humans is scarce.

High in Antioxidants

Eucalyptus oil contains antioxidant molecules, which is one reason it is used as a food preservative. Antioxidant molecules prevent harmful reactions in cells in the human body. In foods, antioxidants prevent oxidation, which helps maintain food safety and quality.

Might Reduce Respiratory Symptoms

Eucalyptus has been used as a remedy to relieve symptoms of respiratory infections such as sore throat, cough, and fever.

A meta-analysis of six randomized controlled studies examined the effects of eucalyptus on cough, a common symptom of respiratory tract infections such as the flu. Although eucalyptus products have been shown to reduce cough frequency, the studies were subject to a high risk of bias. In other words, the results might not be somewhat misleading.

Eucalyptus has many compounds, and eucalyptol (1,8-cineole) is the primary one. A study examined how cineole affects acute bronchitis symptoms (inflammation of the tubes that carry air to the lungs). People with acute bronchitis were given 200 milligrams (mg) of cineole three times daily, along with antiviral treatment. Those who took cineole coughed significantly less frequently.

Might Relieve Pain

Eucalyptus leaves have traditionally been used to relieve pain. A randomized controlled study showed that inhaling eucalyptus can reduce the symptoms of rheumatoid arthritis (RA), an autoimmune disease characterized by joint pain.

Participants with RA inhaled 1 milliliter (mL) of eucalyptus oil for 5 minutes, three times daily, for one month. During the third and fourth weeks of the intervention, those who inhaled eucalyptus oil reported decreased pain intensity compared to participants given a placebo (an inactive substance).

Possible Antiviral Properties

Viruses cause infections such as the flu and COVID-19. They attach to cells and replicate to cause infections. Eucalyptus may have antiviral effects by preventing virus entry and inhibiting replication in cells. 

Many in vitro (test tube) and animal studies have shown that eucalyptus can inhibit human viruses such as influenza (flu), Herpes simplex viruses (HSVs), and SARS-CoV-2 (COVID-19). However, no evidence shows an antiviral effect on humans.

Could Improve Oral Health 

Like any part of the body, the mouth contains bacteria. Changes in the balance of these bacteria can lead to dental issues, such as oral infections and cavities. Therefore, maintaining good oral hygiene is highly important.

Eucalyptus oil may improve oral bacteria and, thus, dental health. One study examined the effects of toothpaste containing eucalyptus oil and Salvadora persica, the plant from which the traditional teeth-cleaning tool, miswak, is derived. Both toothpastes decreased plaque formation, and eucalyptus oil also reduced bleeding in patients with gingivitis, which is an inflammation of the gums. However, the study was small.

Eucalyptus as a Supplement

You may find eucalyptus or eucalyptol supplements on the internet in the form of capsules, liquid extracts, and oils. Other supplements aimed at respiratory relief may also contain eucalyptus leaves. However, studies on the safe dosage and usage of eucalyptus products are limited.

Supplements and essential oils may contain different ingredients than those claimed, which can be dangerous. Consult your healthcare provider before using supplements. They can guide you on dosing and potential risks.

Dosage

Eucalyptus oil is composed of up to 70% eucalyptol (1,8-cineole). In the last ten years, only a few studies have evaluated effective or safe dosages of eucalyptol in humans.

However, over the last two decades, a handful of studies assessed the effects of taking 600 mg daily (three doses of 200 mg) of 1,8-cineole capsules for respiratory conditions such as chronic obstructive pulmonary disease (COPD), asthma, and bronchitis.

The treatment duration generally ranged from 7-15 days, but some long-term studies lasted 12 weeks or six months. It was generally well-tolerated, though side effects such as nausea, headache, ear pain, and nosebleeds were reported. However, evidence remains insufficient to rule out concerns about efficacy and safety.

Risks of Eucalyptus

Eucalyptus oil has a GRAS status for its intended use in foods. The FDA gives this status, which means that the compound is considered likely to be safe for its intended use based on a history of common use and some evidence.

Eucalyptus is considered safe only in very small amounts. Uncontrolled use can lead to serious conditions, such as seizures and metabolic acidosis (a serious condition that develops when the body produces too much acid or the kidneys can't remove enough acid).

According to the European Food Safety Authority (EFSA), accidental high intakes can be fatal. The lowest reported dose causing death in adults was 4-5 milliliters (mL) of eucalyptus oil and 1.9 grams (g) in a 10-year-old child.

Undiluted eucalyptus oil is powerful, so it is generally diluted for topical use. Using undiluted eucalyptus oil topically can cause neurotoxicity (nervous system damage). Even the safety of diluted eucalyptus oil for topical use remains uncertain.

Interactions With Medications

Eucalyptus oil can interact with diabetes medications, amphetamines (nervous system-stimulating drugs), and some medications metabolized by the liver. If you have a chronic (long-term) disease and/or use medications, consult your healthcare provider on possible drug and eucalyptus interactions.

Other Uses for Eucalyptus 

Eucalyptus is also used in products like:

• Skin and hair care products: Eucalyptus-derived compounds are used in cosmetic products such as gel, ointment, and cream.  
• Insect repellants: Eucalyptus oil is made of up to 70% eucalyptol (1,8-cineole), which can work as a natural insect repellent.
• Air fresheners: Eucalyptus oils can be used in aroma lamps, diffusers, and spray mists. However, the safety of inhaling eucalyptus oil is also limited.
  

A Quick Review

Eucalyptus oil can be found in foods, pharmaceuticals, and cosmetic products. Higher doses can cause gastrointestinal (GI) and neurological side effects—and even death.

Eucalyptus is traditionally used to relieve respiratory symptoms and pain. It's also used as an antimicrobial agent. However, further research is needed to determine safety, dosage, and efficacy.