Eucalyptus Oil: Pain Relief from the Plant Kingdom
In looking to avoid potential unpleasant side effects of prescription and over-the-counter pain relief medication, people are seeking a variety of natural alternatives. Compounds found in herbs, roots, rhizomes, and other plants have consistently been shown to produce anti-inflammatory and analgesic effects in the body. Well known examples include turmeric, ginger, rosemary, and garlic. It would be hard to ignore the strong aromas and flavors these substances have, and while we consider these to be beneficial in culinary applications, we might also consider that that the presence of strong smelling active compounds indicates a possible medicinal function as well.
Menthol is among the best known plant extracts for helping to open the airways by easing congestion, and also for soothing inflamed tissue. But another compound, eucalyptol (from eucalyptus) is also beneficial for ameliorating inflammation. 1,8-cineole, the primary active compound in eucalyptus, may be especially helpful for inflammation in the lungs, and eucalyptus has traditionally been used to treat respiratory disorders, owing to its secretolytic properties. There was a method behind your mother’s madness when she rubbed eucalyptol-containing cream on your chest when you came down with a chest cold.
In a mouse model of lipopolysaccharide (LPS)-induced inflammation, eucalyptol administered intragastrically at 10, 30, and 100 mg/kg significantly reduced markers of inflammation compared to the control. Eucalyptol attenuated increases in TNF-α and IL-1β in mouse lung tissue almost as well as prednisone. Eucalyptol also decreased the infiltration of neutrophils and macrophages in bronchoalveolar lavage fluid (BALF), as well as the activity of myeloperoxidase, compared to untreated controls. Pulmonary edema was also significantly reduced in the eucalyptol-treated mice.
Animal studies have consistently shown eucalyptol to have immune-modulating properties. It stimulates phagocytosis by monocyte-derived macrophages without resulting in pro-inflammatory effects. A study on LPS-stimulated human monocytes in vitro showed that eucalyptol exhibited significant, dose-dependent inhibitions of TNF-a (99%), IL-lβ (74%), leukotriene B4 (47%), and thromboxane B2 (91%). The compound has also demonstrated inhibition or reduction of IL-4, IL-5, IL-6, IL-8, and prostaglandin E2.
Eucalyptus extract has been shown to control airway mucus hypersecretion, suggesting it may be especially beneficial for sinusitis, chronic obstructive pulmonary disease (COPD), and asthma. In a double-blind RCT involving individuals with rhinosinusitis who experienced headaches, tenderness to pressure points of the trigeminal nerve, nasal obstruction, and increased nasal secretions (rated by quantity and viscosity), subjects receiving 200mg of eucalyptol T.I.D. showed over 80% improvement after seven days compared to less than 50% improvement for the placebo group. (Both groups received the decongestant xylometazoline three times daily to relieve congestion, which may account for the improvement in the placebo group.)
Asthma sufferers may experience significant improvement with eucalyptol treatment. 1,8-cineole given orally at 200mg T.I.D. led to a 23% increase in forced expiratory volume and a 26% decrease in airway obstruction after just three days of treatment. When lung function was tested four days after treatment ended, these markers were still significantly improved. A double blind RCT showed that the same dosage of eucalyptol in steroid-dependent bronchial asthmatics allowed subjects to tolerate up to 36% reductions in daily prednisolone dosage, compared to a decrease of just 7% in the control group. Twelve of 16 eucalyptol versus just four out of 16 placebo subjects were able to reduce their use of oral steroids. This “steroid-saving effect” is especially promising for individuals who wish to reduce their dependence on medication with potentially unpleasant and adverse side-effects.
Eucalyptol is a potent analgesic, likely owing to its anti-inflammatory effects. Animal studies suggest eucalyptol has a synergistic effect when combined with morphine, and administration of eucalyptol may reduce the morphine dosage needed. In mice, the antinociceptive effects of 1,8-cineole were not reversed by pretreatment with the mu-opiod receptor agonist, naloxone, indicating that eucalyptol works by a non-opioid mechanism. The modulation of inflammatory cytokines and products of arachidonic acid metabolism by eucalyptolsuggests a role for this compound in pain relief, in addition to reducing the effects of “silent inflammation.”
A plant extract that can reduce the need for steroid drugs and morphine? Not bad for the leaves that provide the bulk of a koala bear’s diet!
- David Brady