Tea tree oil

Tea tree oil/Drug Interactions:

  • Antiacne agentsAntiacne agents: In human research, tea tree oil decreased acne lesions, comedones, pustules, and papules (1; 2; 3).
  • AntibioticsAntibiotics: Multiple studies have reported the antimicrobial effects of tea tree oil (24; 10; 11; 25; 12; 27; 28; 29; 30; 32; 33; 34; 35; 109). In human and in vitro research, topical tea tree oil had activity against methicillin-resistant Staphylococcus aureus (MRSA) (58; 53; 54; 111; 112; 96) and vaginal infections (57; 89). In one in vitro study (113), tea tree oil stimulated differentiation of white blood cells.
  • AntifungalsAntifungals: The antifungal effects of tea tree oil have been reported in multiple studies (13; 87; 19; 114; 115; 22; 116; 117; 35; 118). In human research, topical tea tree oil had activity against onychomycosis (119; 51; 55), oral thrush (87; 63; 86; 120), and tinea pedis (119; 88; 56).
  • AntihelminthicsAntihelminthics: Theoretically, tea tree oil may increase the effects of antihelminthics.
  • AntihistaminesAntihistamines: In human research, tea tree oil reduced histamine-induced skin inflammation (78), but in other human research, the size of a histamine-induced weal increased after tea tree oil application (80). In human research, topical tea tree oil decreased allergic reaction to nickel (80; 79). However, in other human research, tea tree oil resulted in allergic contact dermatitis (97; 98; 99; 66; 100; 101; 102; 68; 103; 67; 69; 104; 62; 105; 106; 5; 65; 107).
  • Anti-inflammatory agentsAnti-inflammatory agents: In laboratory studies, tea tree oil showed anti-inflammatory properties (9; 12; 121; 83). However in one in vitro study (113), tea tree oil stimulated differentiation of white blood cells. In human research, tea tree oil decreased inflammation induced by histamine (1).
  • Antineoplastic agentsAntineoplastic agents: In in vitro research, tea tree oil has shown anticancer effects (46).
  • AntiparasiticsAntiparasitics: In human research, tea tree oil cleared ocular Demodex infections (59; 82; 83; 91). Tea tree oil (alone and in combination with lavender) cleared lice infestations (122; 123; 124; 118; 125; 126).
  • Antiviral agentsAntiviral agents: In in vitro research, tea tree oil had antiviral activity (127). In human research, the antiviral activity of tea tree oil was effective against Molluscum contagiosum (a viral skin infection) (60) and warts from the human papilloma virus (92), while its effects against genital herpes simplex virus were inconclusive (85).
  • Cytochrome P450 metabolized agentsCytochrome P450 metabolized agents: In in vitro research, tea tree oil increased the inhibition of the CYP2D6 enzyme (128).
  • Dental agentsDental agents: In human research, tea tree oil decreased gum inflammation and bleeding and had inconclusive effects on dental plaque (77; 31; 129). In vitro, tea tree oil killed periodontopathic bacteria (34). In human research, a mouthwash of tea tree, peppermint, and lemon oils decreased bad breath (130). Patients from an intensive care unit (ICU) used a solution of essential oil (tea tree, peppermint, and lemon oils).
  • Dermatologic agentsDermatologic agents: In human research, topical tea tree oil caused a rash (62) and resulted in allergic contact dermatitis (97; 98; 99; 66; 100; 101; 102; 68; 103; 67; 69; 104; 62; 105; 106; 5; 65; 107; 1), and increased or worsened the weal induced by histamine (80). In other human research, tea tree oil decreased acne lesions, comedones, pustules, papules, dandruff; and allergic reaction to nickel (80; 79; 1; 2; 3; 81). In vitro, tea tree oil dose-dependently decreased skin integrity (131), and, according to secondary sources, topical tea tree oil preparations may result in drying of the skin.
  • Hematologic agentsHematologic agents: In human research, ingestion of tea tree oil resulted in neutropenia (6).
  • Hormonal agentsHormonal agents: Prepubertal gynecomastia has been linked to tea tree oil and lavender oil use (73; 1). According to National Library of Medicine's Drugs and Lactation database (LactMed), tea tree oil may have mild hormonal (antiandrogenic and estrogenic) activity.
  • ImmunosuppressantsImmunosuppressants: In human research, ingestion of tea tree oil resulted in neutropenia (6).
  • Insect repellantsInsect repellants: Tea tree oil (alone and in combination with lavender) cleared lice infestations (122; 123; 124; 118; 125; 126).
  • Neurologic agentsNeurologic agents: In human observational research, tea tree oil taken orally resulted in symptoms of CNS depression (4; 7; 94; 90; 8). In animal research, topical tea tree oil caused ataxia, weakness, muscle tremors, CNS depression, and malcoordination (94).
  • Topical drying agentsTopical drying agents: According to secondary sources, topical tea tree oil preparations may result in drying of the skin and may act additively with other agents, such as tretinoin (Retin-A?, Renova?).
  • Tween 20/Tween 80Tween 20/Tween 80: In in vitro research, the surfactants Tween?20 and Tween?80 caused a decrease in the antibacterial activity of tea tree oil (26).
  • VancomycinVancomycin: Time-to-kill studies found antagonism between vancomycin and tea tree oil (64).

    • Tea tree oil/Herb/Supplement Interactions:

  • Antiacne agentsAntiacne agents: In human research, tea tree oil decreased acne lesions, comedones, pustules, and papules (1; 2; 3).
  • AntibacterialsAntibacterials: Multiple studies have reported the antimicrobial effects of tea tree oil (24; 10; 11; 25; 12; 27; 28; 132; 30; 32; 33; 34; 35; 109). In human and in vitro research, topical tea tree oil had activity against methicillin-resistant Staphylococcus aureus (MRSA) (58; 53; 54; 111; 112; 96) and vaginal infections (57; 89). In one in vitro study (113), tea tree oil stimulated differentiation of white blood cells.
  • AntifungalsAntifungals: The antifungal effects of tea tree oil have been reported in multiple studies (13; 133; 19; 114; 115; 22; 116; 35; 118). In human research, topical tea tree oil had activity against onychomycosis (119; 51; 55), oral thrush (87; 63; 86; 120), and tinea pedis (119; 88; 56).
  • AntihelminthicsAntihelminthics: Theoretically, tea tree oil may increase the effects of antihelminthics.
  • AntihistaminesAntihistamines: In human research, tea tree oil reduced histamine-induced skin inflammation (78), but in other human research, the size of a histamine-induced weal increased after tea tree oil application (80). In human research, topical tea tree oil decreased allergic reaction to nickel (80; 79). However, in other human research, tea tree oil resulted in allergic contact dermatitis (97; 98; 99; 66; 100; 101; 102; 68; 103; 67; 69; 104; 62; 105; 106; 5; 65; 107).
  • Anti-inflammatory herbs and supplementsAnti-inflammatory herbs and supplements: In laboratory studies, tea tree oil showed anti-inflammatory properties (9; 12; 121; 83). However, in one in vitro study (113), tea tree oil stimulated differentiation of white blood cells. In human research, tea tree oil decreased inflammation induced by histamine (1).
  • AntineoplasticsAntineoplastics: In in vitro research, tea tree oil has shown anticancer effects (46).
  • AntiparasiticsAntiparasitics: In human research, tea tree oil cleared ocular Demodex infections (59; 82; 83; 91). Tea tree oil (alone and in combination with lavender) cleared lice infestations (122; 123; 124; 118; 125; 126).
  • Antiviral agentsAntiviral agents: In in vitro research, tea tree oil had antiviral activity (127). In human research, the antiviral activity of tea tree oil was effective against Molluscum contagiosum (a viral skin infection) (60) and warts from the human papilloma virus (92), while its effects against genital herpes simplex virus were inconclusive (85).
  • Cytochrome P450 metabolized herbs and supplementsCytochrome P450 metabolized herbs and supplements: In in vitro research, tea tree oil increased the inhibition of CYP2D6 enzyme (128).
  • Dental agentsDental agents: In human research, tea tree oil decreased gum inflammation and bleeding and had inconclusive effects on dental plaque (77; 31; 129). In vitro, tea tree oil killed periodontopathic bacteria (34). In human research, a mouthwash of tea tree, peppermint, and lemon oils decreased bad breath (130). Patients from an intensive care unit (ICU) used a solution of essential oil (tea tree, peppermint, and lemon oils).
  • Dermatologic agentsDermatologic agents: In human research, topical tea tree oil caused a rash (62), resulted in allergic contact dermatitis (97; 98; 99; 66; 100; 101; 102; 68; 103; 67; 69; 104; 62; 105; 106; 5; 65; 107; 1), and increased or worsened the weal induced by histamine (80). In other human research, tea tree oil decreased acne lesions, comedones, pustules, papules, dandruff, and allergic reaction to nickel (80; 79; 1; 2; 3; 81). In vitro, tea tree oil dose-dependently decreased skin integrity (131), and, according to secondary sources, topical tea tree oil preparations may result in drying of the skin.
  • Hematologic agentsHematologic agents: In human research, ingestion of tea tree oil resulted in neutropenia (6). According to the National Library of Medicine's Drugs and Lactation database (LactMed), tea tree oil may have mild hormonal (antiandrogenic and estrogenic) activity.
  • Hormonal agentsHormonal agents: Prepubertal gynecomastia has been linked to tea tree oil and lavender oil use (73; 1).
  • ImmunosuppressantsImmunosuppressants: In human research, ingestion of tea tree oil resulted in neutropenia (6).
  • Insect repellantsInsect repellants: Tea tree oil (alone and in combination with lavender) cleared lice infestations (122; 123; 124; 118; 125; 126).
  • IodineIodine: In human research, iodine in combination with tea tree oil worked better to clear Molluscum contagiosum compared to either agent alone (60).
  • Neurologic agentsNeurologic agents: In human observational research, tea tree oil taken orally resulted in symptoms of CNS depression (4; 7; 94; 90; 8). In animal research, topical tea tree oil caused ataxia, weakness, muscle tremors, CNS depression, and malcoordination (94).
  • Topical drying agentsTopical drying agents: According to secondary sources, topical tea tree oil preparations may result in drying of the skin and may act additively with other agents, such as tretinoin (Retin-A?, Renova?).

    • Tea tree oil/Food Interactions:

  • Insufficient available evidence.

    • Tea tree oil/Lab Interactions:

  • Complete blood countComplete blood count: In human research, ingestion of tea tree oil resulted in neutropenia (6). In in vitro research, tea tree oil activated white blood cells or induced differentiation of myelocytes into monocytes (113).
  • InterleukinsInterleukins: In humans with Demodex infestation on the eye surface, tea tree oil caused a significant decrease in interleukins-1beta and -17 concentrations in tears (83). In vitro, tea tree oil suppressed the production of tumor necrosis factor-alpha, interleukin-1beta, interleukin-10, and prostaglandin E2 by activated monocytes (121).