Tea tree oil

• CAS: 68647-73-4
• Catalog Number: ACM68647734
• Category: Main Products
• Molecular Weight: 0
• Synonyms: Melasol
• Boiling Point: 165 °C
• Flash Point: 147 °F
• Density: 0.878 g/mL at 25 °C(lit.)
• Appearance: light yellow liquid
• Hazard Statements: Xn,Xi
• Physical State: Liquid
• Refractive Index: n20/D 1.478(lit.)
• Safety Description: 26-36
• Storage Conditions: 2-8 °C
• Supplemental Hazard Statements: H302-H315-H319-H335
• Symbol: GHS07

Case Study

Component-Level Mapping of Tea Tree Oil Antibacterial Efficacy and Dermal Safety

Lee, Chia-Jung, et al. Journal of Food and Drug Analysis 21.2 (2013): 169-176.

Tea tree oil is widely used in cosmetic formulations for acne treatment. This investigation analyzed the correlations between tea tree oil composition, anti-acne activity, and dermal safety using leaves, twigs, and branches from the source plant.
Experimental Protocol: Essential oils were obtained by steam distillation from leaves (TTO-L), twigs (TTO-T), and branches. Composition was determined by GC-MS. Twelve individual terpene components were tested against Propionibacterium acnes and Staphylococcus aureus using agar well-diffusion assays with jojoba oil as vehicle. Six devised tea tree oil formulas were prepared by systematically adjusting terpinen-4-ol (30-50%), 1,8-cineole (0-3%), and minor components. Acute dermal irritation was assessed on Wistar rats using Draize scoring at concentrations of 0.625-10%, and liver function was monitored over 28-day topical application.
Performance Evaluation: Only leaf-derived oil met ISO 4730 specifications, with terpinen-4-ol at 47.3% as the dominant component. Terpinen-4-ol and alpha-terpineol exhibited the strongest anti-P. acnes activity (MIC 2.5%), while terpinolene and alpha-terpinene were most potent against S. aureus (MIC 6.25%). Formulated oils with 50% terpinen-4-ol achieved the greatest antibacterial effect (MIC 1.25%), though none matched the efficacy of natural TTO-L, indicating synergistic contributions from minor constituents. Skin irritation was significant at 5% TTO but absent below 2.5%. Terpinen-4-ol at 1.5% showed no irritation, whereas 1,8-cineole at 0.75% caused mild erythema. A 2% daily application produced no liver enzyme elevation over 28 days. Concentrations below 5% were recommended as both effective and safe for acne treatment.

Multi-Stage Protection Against Ovine Myiasis Using Tea Tree Oil as an Insecticidal and Repellent Biopesticide

Callander, J. T., et al. Veterinary Parasitology 184.2-4 (2012): 271-278.

This study systematically evaluated tea tree oil formulations against every life stage of the blowfly to assess viability as a natural alternative.
Experimental Protocol: Tea tree oil of the terpinen-4-ol chemotype (43% terpinen-4-ol, 1.7% 1,8-cineole) was emulsified in ethoxylated castor oil-based blends. Gravid female repellency was tested in choice and non-choice cage assays using treated wool preparations with liver-based oviposition stimuli, with persistence monitored over 44 days. Ovicidal activity was measured by dipping egg masses in 0.25-10% TTO for 60 seconds and via fumigation chambers.
Performance Evaluation: A 3% TTO wool formulation completely suppressed oviposition for 44 days, far exceeding the 2-3 weeks required for wound healing, with no egg masses deposited on treated wool throughout the trial. Complete egg mortality was achieved at 1% TTO, and first instar larvae showed 100% mortality at the same concentration (LD₅₀ = 0.61%). Second and third instar larvae required 2.5% TTO for complete kill in agar feeding assays. Even at 0.5%, TTO strongly repelled third instar larvae, causing rapid evacuation of treated areas. The compound stimulated larvae to leave wounded tissue, an advantageous feature for myiasis management. However, combining TTO with conventional larvicides (diazinon, ivermectin, boric acid) paradoxically reduced mortality due to accelerated avoidance behavior limiting insecticide contact time.

Triple-Active Botanical Cream Combining Tea Tree Oil with Propolis and Aloe Vera Outperforms Erythromycin in Acne Therapy

Mazzarello, V., et al. Clinical pharmacology: advances and applications (2018): 175-181.

This randomized, double-blind clinical trial compared a novel three-component botanical formulation containing tea tree oil, propolis, and Aloe vera against standard erythromycin therapy and placebo in patients with mild to moderate acne vulgaris.
Experimental Protocol: Sixty patients aged 14-34 years with mild to moderate facial acne (fewer than 20 comedones and 50 papules/pustules) were randomly assigned to three groups of 20. Group A received a cream containing 20% propolis, 3% tea tree oil, and 10% Aloe vera leaf juice (PTAC). Group B received 3% erythromycin cream (ERC). Group C received vehicle only (placebo). Products were applied twice daily for 30 days. Acne severity was assessed through lesion counting, acne severity index (ASI), and total lesion count (TLC) at baseline, day 15, and day 30. Biophysical measurements included sebumetry, skin pH, and erythema index on healthy skin, papular lesions, and scar areas.
Performance Evaluation: The PTAC formulation significantly outperformed ERC across multiple endpoints. ASI reduction at 30 days reached 66.7% for PTAC versus 49.7% for ERC (P=0.037), while TLC decreased by 63.7% versus 46.5% (P=0.001). Papule counts dropped by 61.4% with PTAC compared to 45.4% with ERC. Notably, PTAC demonstrated faster action on erythematous scars, showing significant improvement within the first 15 days versus no early effect from ERC. Neither active treatment altered sebum production, skin surface pH, or perilesional erythema, confirming the formulations did not compromise barrier function or cause irritation. The triple combination of tea tree oil antimicrobial action, propolis antibacterial and wound-healing properties, and Aloe vera anti-inflammatory activity achieved superior outcomes through complementary mechanisms without selecting for resistant organisms.