Eucalyptus oil

Eucalyptus/Drug Interactions:

  • 5-Fluorouracil (5-FU)5-Fluorouracil (5-FU): Eucalyptus has been found to enhance permeation of topical 5-fluorouracil (5-FU) through rat skin (61). Using topical 5-FU and eucalyptus concomitantly may potentiate the effects of 5-FU.
  • AmphetamineAmphetamine: In vivo and in vitro studies have demonstrated reductions in amphetamine levels when used with eucalyptol, a component of eucalyptus (39). Human data are lacking.
  • AntibioticsAntibiotics: Animal and basic science research suggest that eucalyptus may have antibacterial effects against many types of bacteria, including Alicyclobacillus acidoterretris, Bacillus cereus, E. coli, Enterococcus faecalis, MRSA, Propionibacterium acnes, S. aureus, Trichophyton mentagrophytes, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Streptococcus mutans, Aeruginosa, Bac. Subtilis, Staph. epidermidis, and Streptococcus sobrinus (7; 62; 63; 64; 14; 9; 10; 65). Therefore, eucalyptus may theoretically increase the effects of antibiotics.
  • Antidiabetic agentsAntidiabetic agents: Eucalyptus has been shown to lower blood glucose concentrations in diabetic animals (20). Use with hypoglycemic agents may theoretically result in additive effects.
  • AntifungalsAntifungals: Multiple eucalyptus species have exhibited anti-fungal properties in vitro (66; 67; 68; 10). Therefore, eucalyptus oil may theoretically increase the effects of antifungal agents.
  • AntihypertensivesAntihypertensives: Eucalyptus oil may interact with antihypertensive agents, as cardiovascular collapse with severe intoxication has been cited in case reports (36; 37).
  • Anti inflammatory agentsAnti inflammatory agents: An in vitro study of human blood monocytes reported dose-dependent, significant inhibition of multiple cytokines, with suggested application in the treatment of airway inflammation (69; 70). Anti-inflammatory activity and anti-nociceptive effects have been demonstrated elsewhere in animal models (71; 6). Therefore, eucalyptus may theoretically increase the effects of anti-inflammatory agents.
  • Antineoplastic agentsAntineoplastic agents: Eucalyptus has been found to enhance permeation of topical 5-fluorouracil (5-FU) through rat skin (61). Using topical 5-FU and eucalyptus concomitantly may potentiate the effects of 5-FU. Eucalyptus camaldulensis has been screened for cytotoxic activity against human ECV-304 cells (72). It has also demonstrated anti-tumor promoting effects, as well as apoptosis-inducing effects in human myeloid leukemia cells (18) and inhibiting effects of human plasminogen activator inhibitor (73). Therefore, eucalyptus may theoretically interact with cancer treatments.
  • AntiprotozoalsAntiprotozoals: It has been suggested that the Australian Koala's ingestion and skin surface excretion of eucalyptus may have anti-parasitic effects (74). The extract of Eucalyptus comaldensis (50mg in 0.1mL medium) at pH 5.35 caused death of T. vaginalis after 24 hours (26). Therefore, eucalyptus may theoretically increase the effects of some antiparasitic agents.
  • Antiviral agentsAntiviral agents: In cell cultures, eucalyptus has exhibited anti-viral activity against the herpes simplex virus (HSV-1, HSV-2) (75). Therefore, eucalyptus may theoretically increase the effects of some antivirals.
  • Appetite stimulantsAppetite stimulants: Eucalyptus has demonstrated appetite suppressant effects in animal feeding studies (76). Therefore, eucalyptus may theoretically decrease the effects of appetite stimulants.
  • Cytochrome P450 metabolized agents, cytochrome P450 3A(4,5,7) substratesCytochrome P450 metabolized agents, cytochrome P450 3A(4,5,7) substrates: The terpine 1,8-cineole (eucalyptol), a principal component of eucalyptus, has been found to possess cytochrome P450-inducing activity in animals (38) and in vitro, specifically affecting levels of aminopyrine, amphetamine, zoxazolamine, and phenylbutazone (39). Initial evidence suggests that 1,8-cineole is a substrate (metabolite) of CYP 3A specifically, with levels affected by that enzyme (41). Other research has isolated the metabolite of eucalyptol, 2-exo-hydroxy-1,8-cineole, as a substrate of cytochrome P450 (40; 41).
  • Disulfiram (Antabuse?)Disulfiram (Antabuse?): Many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with disulfiram (Antabuse?).
  • ExpectorantsExpectorants: Eucalyptus, either alone or in combination with other extracts, has been shown to have expectorant activity (19; 28; 74; 77). Therefore, eucalyptus may increase the effects of expectorants.
  • Gastrointestinal agents, miscellaneousGastrointestinal agents, miscellaneous: Volatile constituents may cause mucosal irritation and possible choleretic activity. Therefore, eucalyptus may interact with gastrointestinal agents that affect the production and flow of bile.
  • Insect repellantsInsect repellants: Eucalyptus oil has been shown to have insect repellent effects, especially against mosquitoes (Aedes albopictus, Ae. aegypti, and Culex pipiens pallens) (78; 79; 80), live mites (81), and biting arthropods (82). Therefore, eucalyptus oil may increase the effects of insect repellants.
  • PentobarbitalPentobarbital: In vivo and in vitro studies have demonstrated reductions in pentobarbital levels when used with eucalyptol, a component of eucalyptus (39). Human data are lacking.
  • Metronidazole (Flagyl?)Metronidazole (Flagyl?): Many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl?).
  • Neurologic agentsNeurologic agents: In multiple case reports, oral ingestion of eucalyptus oil has been associated with central nervous system (CNS) depression, characterized by drowsiness, loss of consciousness, ataxia, slurred speech, vertigo, hyper-reflexia and headache (36; 58; 37). Animal study has revealed sedative effects that are not mediated by a mu-receptor mechanism (6). Therefore, additive effects may occur when taken with other neurologic agents.
  • SedativesSedatives: In multiple case reports, oral ingestion of eucalyptus oil has been associated with central nervous system (CNS) depression, characterized by drowsiness, loss of consciousness, ataxia, slurred speech, vertigo, hyper-reflexia and headache (36; 58; 37). Animal study has revealed sedative effects that are not mediated by a mu-receptor mechanism (6). Therefore, additive effects may occur when taken with other sedative agents.
  • VasodilatorsVasodilators: Researchers tested the effects of topical Eucalyptamint? (eucalyptus oil, lanolin, and 15% menthol) on cutaneous blood flow and temperature in humans (83). Subjective perceptions were not significantly different, although blood flow, skin, and muscle temperatures were significantly altered for 45 minutes compared to placebo or to baseline measurements. Therefore, eucalyptus oil may interact with vasodilators.

    • Eucalyptus/Herb/Supplement Interactions:

  • AntibacterialsAntibacterials: Animal and basic science research suggest that eucalyptus may have antibacterial effects against many types of bacteria, including Alicyclobacillus acidoterretris, Bacillus cereus, E. coli, Enterococcus faecalis, MRSA, Propionibacterium acnes, S. aureus, Trichophyton mentagrophytes, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Streptococcus mutans, Aeruginosa, Bac. Subtilis, Staph. epidermidis, and Streptococcus sobrinus (62; 64; 10; 65; 63; 14; 7; 9). Therefore, eucalyptus may theoretically increase the effects of antibacterials.
  • AntifungalsAntifungals: Multiple eucalyptus species have exhibited anti-fungal properties in vitro (66; 67; 68; 10). Therefore, eucalyptus oil may theoretically increase the effects of antifungal agents.
  • Anti inflammatory herbsAnti inflammatory herbs: An in vitro study of human blood monocytes reported dose-dependent, significant inhibition of multiple cytokines, with suggested application in the treatment of airway inflammation (69; 70). Anti-inflammatory activity and anti-nociceptive effects have been demonstrated elsewhere in animal models (71; 6). Therefore, eucalyptus may theoretically increase the effects of anti-inflammatory agents.
  • AntineoplasticsAntineoplastics: Eucalyptus has been found to enhance permeation of topical 5-fluorouracil (5-FU) through rat skin (61). Using topical 5-FU and eucalyptus concomitantly may potentiate the effects of 5-FU. Eucalyptus camaldulensis has been screened for cytotoxic activity against human ECV-304 cells (72). It has also demonstrated anti-tumor promoting effects, as well as apoptosis-inducing effects in human myeloid leukemia cells (18) and inhibiting effects of human plasminogen activator inhibitor (73). Therefore, eucalyptus may theoretically interact with cancer treatments.
  • AntioxidantsAntioxidants: Eucalyptus has been shown to have antioxidant activity (84; 85). Therefore, eucalyptus may have additive effects when taken with antioxidants.
  • Antiparasitics: Antiparasitics: It has been suggested that the Australian Koala's ingestion and skin surface excretion of eucalyptus may have anti-parasitic effects (74). The extract of Eucalyptus comaldensis (50mg in 0.1mL medium) at pH 5.35 caused death of T. vaginalis after 24 hours (26). Therefore, eucalyptus may theoretically increase the effects of some antiparasitic agents.
  • AntiviralsAntivirals: In cell cultures, eucalyptus has exhibited anti-viral activity against the herpes simplex virus (HSV-1, HSV-2) (75). Therefore, eucalyptus may theoretically increase the effects of some antivirals.
  • Appetite suppressantsAppetite suppressants: Eucalyptus has demonstrated appetite suppressant effects in animal feeding studies (76). Therefore, eucalyptus may theoretically increase the effects of appetite suppressants.
  • BorageBorage: Eucalyptus may worsen the side effects of borage, although reliable research is lacking in this area.
  • ColtsfootColtsfoot: Eucalyptus may worsen the side effects of coltsfoot, although reliable research is lacking in this area.
  • ComfreyComfrey: Eucalyptus may worsen the side effects of comfrey, although reliable research is lacking in this area.
  • Cytochrome P450 metabolized herbs and supplements, cytochrome P450 3A(4,5,7) substratesCytochrome P450 metabolized herbs and supplements, cytochrome P450 3A(4,5,7) substrates: The terpine 1,8-cineole (eucalyptol), a principal component of eucalyptus, has been found to possess cytochrome P450 inducing activity in animals (38) and in vitro, specifically affecting levels of aminopyrine, amphetamine, zoxazolamine, and phenylbutazone (39). Initial evidence suggests that 1,8-cineole is a substrate (metabolite) of CYP 3A specifically, with levels affected by that enzyme (41). Other research has isolated the metabolite of eucalyptol, 2-exo-hydroxy-1,8-cineole, as a substrate of cytochrome P450 (40; 41).
  • ExpectorantsExpectorants: Eucalyptus, either alone or in combination with other extracts, has been shown to have expectorant activity (19; 28; 74; 77). Therefore, eucalyptus may increase the effects of expectorants.
  • Gastrointestinal herbs and supplementsGastrointestinal herbs and supplements: Volatile constituents may cause mucosal irritation and possible choleretic activity. Therefore, eucalyptus may interact with gastrointestinal agents that affect the production and flow of bile.
  • Hound's toothHound's tooth: Eucalyptus may worsen the side effects of hound's tooth, although reliable research is lacking in this area.
  • HypoglycemicsHypoglycemics: Eucalyptus has been shown to lower blood glucose concentrations in diabetic animals (20). Eucalyptus use with hypoglycemic agents may theoretically result in additive effects.
  • HypotensivesHypotensives: Eucalyptus oil may interact with hypotensives agents, as cardiovascular collapse with severe intoxication has been cited in case reports (36; 37).
  • Insect repellantsInsect repellants: Eucalyptus oil has been shown to have insect repellent effects, especially against mosquitoes (Aedes albopictus, Ae. aegypti, and Culex pipiens pallens) (78; 79; 80), live mites (81), and biting arthropods (82). Therefore, eucalyptus oil may increase the effects of insect repellants.
  • Senecio speciesSenecio species: Eucalyptus may worsen the side effects of Senecio species, although reliable research is lacking in this area.
  • Neurologic herbs and supplementsNeurologic herbs and supplements: In multiple case reports, oral ingestion of eucalyptus oil has been associated with central nervous system (CNS) depression, characterized by drowsiness, loss of consciousness, ataxia, slurred speech, vertigo, hyper-reflexia and headache (36; 58; 37). Animal study has revealed sedative effects that are not mediated by a mu-receptor mechanism (6). Therefore, additive effects may occur when taken with other neurologic agents.
  • Pyrrolizidine alkaloid containing plantsPyrrolizidine alkaloid containing plants: Based on anecdote, eucalyptus may potentiate the toxicity of pyrrolizidine alkaloid containing plants, such as borage, coltsfoot, comfrey, hound's tooth, or Senecio species.
  • SedativesSedatives: In multiple case reports, oral ingestion of eucalyptus oil has been associated with central nervous system (CNS) depression, characterized by drowsiness, loss of consciousness, ataxia, slurred speech, vertigo, hyper-reflexia and headache (36; 58; 37). Animal study has revealed sedative effects that are not mediated by a mu-receptor mechanism (6). Therefore, additive effects may occur when taken with other sedative agents.
  • Vasodilator herbs and supplementsVasodilator herbs and supplements: Researchers tested the effects of topical Eucalyptamint? (eucalyptus oil, lanolin, and 15% menthol) on cutaneous blood flow and temperature in humans (83). Subjective perceptions were not significantly different, although blood flow, skin, and muscle temperatures were significantly altered for 45 minutes compared to placebo or to baseline measurements. Therefore, eucalyptus oil may interact with vasodilators.

    • Eucalyptus/Food Interactions:

  • Milk and lipidsMilk and lipids: In theory, the absorption of eucalyptus may be increased in the presence of milk or lipids.

    • Eucalyptus/Lab Interactions:

  • Serum glucoseSerum glucose: Eucalyptus has been shown to lower blood glucose concentrations in diabetic animals (20). Human data are lacking.