An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetherolea, or simply as the oil of the plant from which they were extracted, such as oil of clove英语oil of clove. An oil is "essential" in the sense that it contains the "essence of" the plant's fragrance—the characteristic fragrance of the plant from which it is derived.[1] The term essential used here does not mean indispensable as with the terms essential amino acid or essential fatty acid which are so called since they are nutritionally required by a given living organism.[2]

精油通常使用蒸馏法,其中水蒸气蒸馏最常使用。其他方法包含壓榨法英语Ram press (food)溶劑萃取法、浸泡法、脂吸法、超臨界萃取法。其使用於香水化妝品肥皂、家中清潔用品和其他產品,用於調整食物或飲料的香味,增加香氣


Essential oils have been used medicinally throughout history. The earliest recorded mention of the techniques and methods used to produce essential oils is believed to be that of Ibn al-Baitar英语Ibn al-Baitar (1188–1248), an Al-Andalusian (Muslim-controlled Spain) physician, pharmacist and chemist.[3]

Rather than refer to essential oils themselves, modern works typically discuss specific chemical compounds of which the essential oils are composed. For example: methyl salicylate rather than "oil of wintergreen".[4][5]

Interest in essential oils has revived in recent decades with the popularity of aromatherapy, a branch of alternative medicine that uses essential oils and other aromatic compounds. Oils are volatilized, diluted in a carrier oil英语carrier oil and used in massage, diffused in the air by a nebulizer英语nebulizer, heated over a candle flame, or burned as incense.

Medical applications proposed by those who sell medicinal oils range from skin treatments to remedies for cancer and often are based solely on historical accounts of use of essential oils for these purposes. Claims for the efficacy of medical treatments, and treatment of cancers in particular, are now subject to regulation in most countries.



最常見的精油,例如:薰衣草薄荷茶樹油广藿香,和桉树是由蒸餾提取的。由木材树皮树根種子果皮英语peel (fruit)組成的植物原料,在水上放上蒸餾器英语alembic(蒸餾裝置)。當水加熱時,蒸汽經過植物原料,並與揮發性化合物結合,並於冷凝管凝結成液體,最後收集於容器中。



多數柑橘是以機械壓榨或冷壓果皮萃取,如同橄欖油萃取英语olive oil extraction。由於生產量相對較大、生長和收穫成本低,故比其他其他精油便宜。檸檬和甜柑橘精油也是柑橘属的副產品



大多數的花揮發油太少,無法使用冷壓萃取,且化學結構容易因水蒸氣高溫破壞。而溶液萃取的溶剂可為己烷超臨界二氧化碳[7]。萃取自己烷和其他疏水性溶劑稱為凝香體英语Concrete (perfumery),為一種混合精油、树脂和其他親油性 (油溶性)產物。

雖然香氣濃郁,但是凝香體含有大量不具有香味的蠟和樹脂。通常使用另一個溶劑,例如乙醇,用來從凝香體中提取芳香油。將酒精溶液冷卻至−18 °C(0 °F)超過48小時,使脂類沉澱。The precipitates are then filtered out and the ethanol is removed from the remaining solution by evaporation, vacuum purge, or both, leaving behind the 原精英语Absolute (fragrance).

超臨界二氧化碳在超臨界流體萃取中作為溶劑。此方法可避免石化英语petrochemical殘留於產品中,和避免使用蒸汽蒸餾時損失前調。 It does not yield an absolute directly. The supercritical carbon dioxide will extract both the waxes and the essential oils that make up the concrete. Subsequent processing with liquid carbon dioxide, achieved in the same extractor by merely lowering the extraction temperature, will separate the waxes from the essential oils. 較低溫度防止了化合物的分解和變性。當萃取完成後,將壓力降低,使二氧化碳揮發,不會留殘餘物。


Carvacrol英语Carvacrol, a terpene found in oregano oil, inhibits the growth of several bacteria strains including Escherichia coli and Bacillus cereus.[需要可靠醫學來源] In Pseudomonas aeruginosa, it causes damages to the cell membrane of these bacteria and, unlike other terpenes, inhibits their proliferation.[來源請求] The cause of the antimicrobial properties is believed to be disruption of the bacteria membrane. Carvacrol is a potent activator of the human ion channels transient receptor potential V3 (TRPV3) and A1 (TRPA1).[來源請求]

Another example of the medicinal value of essential oils is thymol, isomeric with carvacrol and found in oil of the common spice thyme. Thymol is part of a naturally occurring class of compounds known as biocides, with strong antimicrobial attributes when used alone or with other biocides such as carvacrol.[8][9][10] In addition, naturally occurring biocidal agents such as thymol can reduce bacterial resistance to common drugs such as penicillin. Numerous studies have demonstrated the antimicrobial effects of thymol, ranging from inducing antibiotic susceptibility in drug-resistant pathogens to powerful antioxidant properties.[需要可靠醫學來源] Research demonstrates that thymol and carvacrol reduce bacterial resistance to antibiotics through a synergistic effect,[需要可靠醫學來源] and thymol has been shown to be an effective fungicide, particularly against fluconazole-resistant strains.[需要可靠醫學來源] Carvacrol and thymol have been demonstrated to have a strong antimutagenic effect.[需要可靠醫學來源] In addition, there is evidence that thymol has antitumor properties.[需要可靠醫學來源] Though the exact mechanism is unknown, some evidence suggests thymol effects at least some of its biocidal properties by membrane disruption. Thymol has been shown to act as a positive allosteric modulator of GABAA in vitro.

Studies have shown that certain essential oils[哪個/哪些?] may have the ability to prevent the transmission of some drug-resistant strains of pathogen, specifically Staphylococcus, Streptococcus and Candida.[11]

Taken by mouth, many essential oils can be dangerous in high concentrations. Typical effects begin with a burning feeling, followed by salivation. In the stomach, the effect is carminative英语carminative, relaxing the gastric sphincter and encouraging eructation (belching). Further down the gut, the effect typically is antispasmodic.[12][13] Typical ingredients for such applications include eucalyptus oils, menthol, capsaicin, anise and camphor.[來源請求]

Different essential oils may have drastically different pharmacology. Those that do work well for upper respiratory tract and bronchial problems act variously as mild expectorants and decongestants.[需要可靠醫學來源] Some act as locally anesthetic counterirritant英语counterirritants and, thereby, exert an antitussive effect.[12][14]

Some essential oils, such as those of juniper and agathosma英语agathosma, are valued for their diuretic effects.[15][不可靠的醫學來源?] With relatively recent concerns about the overuse of antibacterial agents,[16] many essential oils have seen a resurgence in off-label use英语off-label use for such properties and are being examined for this use clinically.[17]

Many essential oils affect the skin and mucous membranes in ways that are valuable or harmful. Many essential oils, particularly tea tree oil, may cause contact dermatitis英语contact dermatitis.[18][19][20][21] They are used in antiseptics and liniments in particular. Typically, they produce rubefacient英语rubefacient irritation at first and then counterirritant numbness. Turpentine oil and camphor are two typical examples of oils that cause such effects. Menthol and some others produce a feeling of cold followed by a sense of burning. This is caused by its effect on heat-sensing nerve endings. Some essential oils, such as clove oil or eugenol, were popular for many hundred years in dentistry as antiseptics and local anesthetics.

Use in aromatherapy编辑

Essential oils are used in aromatherapy as part of, for example, essential oil diffusers.

Aromatherapy is a form of alternative medicine in which healing effects are ascribed to the aromatic compounds in essential oils and other plant extracts. Aromatherapy appears to be useful to induce relaxation, especially when administered with massage.[22] Use of essential oils may cause harm including allergic reactions and skin irritation; there has been at least one case of death.[23]


精油大多是親脂性,通常不相溶於水,可使用溶剂像是乙醇聚乙二醇稀釋。 安全稀釋精油最常見的方法為使用基底油稀釋,這可以是任何植物油,像是荷荷巴油、椰子油、麥芽油、橄欖油和鱷梨油。[24]



果皮英语Peel (fruit)




尤加利精油,亦稱為桉樹精油,而市售精油大多數是萃取自藍桉葉。Steam-distilled eucalyptus oil is used throughout 亞洲、非洲、拉丁美洲和南美洲 as a primary cleaning/disinfecting agent added to soaped mop and countertop cleaning solutions; it also possesses insect and limited vermin control properties.[29] 注意,桉樹有幾百種品種, and perhaps some dozens are used to various extents as sources of essential oils. Not only do the products of different species differ greatly in characteristics and effects, but also the products of the very same tree can vary grossly.[30]


薰衣草精油英语Lavender oil作為香水原料已有許久的時間[31]。然而,也可作為雌激素和抗雄激素,這引起青春期前的孩子和孕婦一些麻煩[32]。薰衣草精油也可以驅蟲[33]


玫瑰油英语Rose oil是由突厥蔷薇百叶蔷薇花瓣萃取,而蒸餾產生的為玫瑰油或玫瑰精油,經由溶劑萃取稱為玫瑰原精。


The potential danger of an essential oil is sometimes relative to its level or grade of purity, and sometimes related to the toxicity of specific chemical components of the oil. Many essential oils are designed exclusively for their aroma-therapeutic quality; these essential oils generally should not be applied directly to the skin in their undiluted or "neat" form. Some can cause severe irritation, provoke an allergic reaction and, over time, prove hepatotoxic英语hepatotoxic.

Some essential oils, including many of the citrus peel oils, are photosensitizers英语Photosensitivity in humans, increasing the skin's vulnerability to sunlight.[34]

Industrial users of essential oils should consult the safety data sheets (SDS) to determine the hazards and handling requirements of particular oils. Even certain therapeutic grade oils can pose potential threats to individuals with epilepsy or pregnant women.


每一種精油的闪点都不同,但茶樹精油、薰衣草精油和柑橘類精油,歸類於第三類易燃液體英语HAZMAT Class 3 Flammable Liquids中,因閃點為50至60 °C(122至140 °F)。


雌激素抗雄激素活性已經有in vitro相關研究,並以茶樹油薰衣草精油。 Case 研究結果建議the oils可能與 in some cases of 男性乳房发育症相關,異常的乳房組織生長於青春時期的男性。[35][36]然而,這些主張已經遭受質疑[37][不可靠的醫學來源?] and the European Commission's Scientific Committee on Consumer Safety has dismissed the claims saying "Since the hormonal active ingredients of Tea Tree Oil were shown not to penetrate the skin, the hypothesized correlation of the finding of 3 cases of gynecomastia to the topical use of Tea Tree Oil is considered implausible." [38]


Exposure to essential oils may cause a contact dermatitis英语contact dermatitis.[19][20][21] Essential oils can be aggressive toward rubbers and plastics, so care must be taken in choosing the correct handling equipment. Glass syringes are often used, but have coarse volumetric graduations. Chemistry syringes are ideal, as they resist essential oils, are long enough to enter deep vessels, and have fine graduations, facilitating quality control. Unlike traditional pipettes, which have difficulty handling viscous fluids, the chemistry syringe has a seal and piston arrangement which slides inside the pipette, wiping the essential oil off the pipette wall.


Essential oils are used extensively as GRAS flavoring agents in foods, beverages, and confectioneries according to strict Good Manufacturing Practice (GMP) and flavorist英语flavorist standards. Pharmacopoeia standards for medicinal oils should be heeded. Some oils can be toxic to some domestic animals, cats in particular.[39] The internal use of essential oils can pose hazards to pregnant women, as some can be abortifacient英语abortifacients in dose 0.5–10 ml, and thus should not be used during pregnancy.

Pesticide residues编辑

There is some concern about pesticide residues in essential oils, particularly those used therapeutically. For this reason, many practitioners of aromatherapy buy organically produced oils. Not only are pesticides present in trace quantities, but also the oils themselves are used in tiny quantities and usually in high dilutions. Where there is a concern about pesticide residues in food essential oils, such as mint or orange oils, the proper criterion is not solely whether the material is organically produced, but whether it meets the government standards based on actual analysis of its pesticide content.[40]


The use of essential oils in pregnancy is not recommended due to inadequate published evidence to demonstrate evidence of safety.[41] Pregnant women often report an abnormal sensitivity to smells and taste,[42] and essential oils can cause irritation and nausea.


The following table lists the LD50 or median lethal dose for common oils; this is the dose required to kill half the members of a tested animal population. LD50 is intended as a guideline only, and reported values can vary widely due to differences in tested species and testing conditions.[43]

Common Name Oral LD50 Dermal LD50 Notes
Neem 14 g/kg >2 g/kg
Lemon myrtle 2.43 g/kg 2.25 g/kg
Frankincense >5 g/kg >5 g/kg Boswellia carterii
Frankincense >2 g/kg >2 g/kg Boswellia sacra
Indian frankincense >2 g/kg >2 g/kg Boswellia serrata
Ylang-ylang >5 g/kg >5 g/kg
Cedarwood >5 g/kg >5 g/kg
Roman chamomile >5 g/kg >5 g/kg
White camphor >5 g/kg >5 g/kg Cinnamomum camphora, extracted from leaves
Yellow camphor 3.73 g/kg >5 g/kg Cinnamomum camphora, extracted from bark
Hot oil 3.80 g/kg >5 g/kg Cinnamomum camphora, oil extracted from leaves
Cassia 2.80 g/kg 0.32 g/kg

Standardization of its derived products编辑

In 2002, ISO published ISO 4720 in which the botanical names of the relevant plants are standardized.[44] The rest of the standards with regards to this topic can be found in the section of ICS 71.100.60 [45]



  1. ^ essential oil. Oxford English Dictionary online, American English. [2014-07-21]. 
  2. ^ Reeds, P. J. Dispensable and indispensable amino acids for humans. The Journal of nutrition. 2000, 130 (7): 1835S–40S. PMID 10867060. 
  3. ^ Houtsma, M.Th. E. J. Brill's First Encyclopaedia of Islam, 1913–1936 4. Brill英语Brill Publishers. 1993: 1011–. ISBN 978-90-04-09790-2. 
  4. ^ Gilman, A. G.; Rall, T. W.; Nies, Alan S.; Taylor, Palmer (编). Goodman & Gilman's The Pharmacological Basis of Therapeutics英语Goodman & Gilman's The Pharmacological Basis of Therapeutics 8th. New York: Pergamon英语Pergamon Press. 1990. ISBN 0-08-040296-8.  [页码请求]
  5. ^ Klaassen, Curtis D.; Amdur, Mary O.; Casarett, Louis J.; Doull, John. Casarett and Doull's Toxicology: The Basic Science of Poisons. New York: McGraw-Hill. 1991. ISBN 0071052399. [页码请求]
  6. ^ Ryman, Daniele. The Aromatherapy Handbook: The Secret Healing Power Of Essential Oils. Century Publishing CO. Ltd. 1984: Chapter 3. ISBN 9780852072158. 
  7. ^ Aizpurua-Olaizola, Oier; Ormazabal, Markel; Vallejo, Asier; Olivares, Maitane; Navarro, Patricia; Etxebarria, Nestor; Usobiaga, Aresatz. Optimization of supercritical fluid consecutive extractions of fatty acids and polyphenols from Vitis vinifera grape wastes. Journal of Food Science. 2015-01-01, 80 (1): E101–107. ISSN 1750-3841. PMID 25471637. doi:10.1111/1750-3841.12715. 
  8. ^ Carvacrol data sheet from Sigma-Aldrich. 
  9. ^ Soares, I.H.; Loreto, É.S.; Rossato, L.; Mario, D.N.; Venturini, T.P.; Baldissera, F.; Santurio, J.M.; Alves, S.H. In vitro activity of essential oils extracted from condiments against fluconazole-resistant and -sensitive Candida glabrata. Journal de Mycologie Médicale / Journal of Medical Mycology. 2015, 25 (3): 213–7. PMID 26281965. doi:10.1016/j.mycmed.2015.06.003. 
  10. ^ Mandras, Narcisa; Nostro, Antonia; Roana, Janira; Scalas, Daniela; Banche, Giuliana; Ghisetti, Valeria; Del Re, Simonetta; Fucale, Giacomo; Cuffini, Anna Maria; Tullio, Vivian. Liquid and vapour-phase antifungal activities of essential oils against Candida albicans and non-albicans Candida. BMC Complementary and Alternative Medicine. 2016, 16 (1): 330. PMC 5006570 . PMID 27576581. doi:10.1186/s12906-016-1316-5. 
  11. ^ Warnke, Patrick H.; Becker, Stephan T.; Podschun, Rainer; Sivananthan, Sureshan; Springer, Ingo N.; Russo, Paul A.J.; Wiltfang, Joerg; Fickenscher, Helmut; Sherry, Eugene. The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections. Journal of Cranio-Maxillofacial Surgery. 2009, 37 (7): 392–7. PMID 19473851. doi:10.1016/j.jcms.2009.03.017. 
  12. ^ 12.0 12.1 Sapeika, Norman. Actions and Uses of Drugs. A.A. Balkema. 1963. [页码请求]
  13. ^ Braun, Leslie. Herbs & Natural Supplements. Australia: Elsevier. 2005: 42–43. ISBN 978-0-7295-3910-4. 
  14. ^ Haneke, Karen E, Turpentine (Turpentine Oil, Wood Turpentine, Sulfate Turpentine, Sulfite Turpentine) [8006-64-2]: Review of Toxicological Literature (PDF) (Contract No. N01–ES–65402), National Institute of Environmental Health Sciences英语National Institute of Environmental Health Sciences, February 2002 [页码请求]
  15. ^ Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina. The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd. Edinburgh: E & S Livingstone. 1962. [页码请求]
  16. ^ Levy, Stuart B. Antibacterial Household Products: Cause for Concern. Emerging Infectious Diseases. 2001, 7 (7): 512–5. PMC 2631814 . PMID 11485643. doi:10.3201/eid0707.017705. 
  17. ^ Singh, G.; Kapoor, I. P. S.; Pandey, S. K.; Singh, U. K.; Singh, R. K. Studies on essential oils: Part 10; Antibacterial activity of volatile oils of some spices. Phytotherapy Research. 2002, 16 (7): 680–2. PMID 12410554. doi:10.1002/ptr.951. 
  18. ^ Larson, David; Jacob, Sharon E. Tea Tree Oil. Dermatitis. 2012, 23 (1): 48–9. PMID 22653070. doi:10.1097/DER.0b013e31823e202d. 
  19. ^ 19.0 19.1 Trattner, Akiva; David, Michael; Lazarov, Aneta. Occupational contact dermatitis due to essential oils. Contact Dermatitis. 2008, 58 (5): 282–4. PMID 18416758. doi:10.1111/j.1600-0536.2007.01275.x. 
  20. ^ 20.0 20.1 Bleasel, Narelle; Tate, Bruce; Rademaker, Marius. Allergic contact dermatitis following exposure to essential oils. Australasian Journal of Dermatology. 2002, 43 (3): 211–3. PMID 12121401. doi:10.1046/j.1440-0960.2002.00598.x. 
  21. ^ 21.0 21.1 Isaksson, M; Brandão, F. M.; Bruze, M; Goossens, A. Short Communications. Contact Dermatitis. 2000, 43 (1): 41–2. PMID 10902588. doi:10.1034/j.1600-0536.2000.043001041.x. 
  22. ^ Lee, Myeong Soo; Choi, Jiae; Posadzki, Paul; Ernst, Edzard. Aromatherapy for health care: An overview of systematic reviews. Maturitas. 2012, 71 (3): 257–60. PMID 22285469. doi:10.1016/j.maturitas.2011.12.018. 
  23. ^ Posadzki, P; Alotaibi, A; Ernst, E. Adverse effects of aromatherapy: A systematic review of case reports and case series. The International journal of risk & safety in medicine. 2012, 24 (3): 147–61. PMID 22936057. doi:10.3233/JRS-2012-0568 (不活跃 2017-04-02). 
  24. ^
  25. ^ Balsam, Peru. Hippylife. [2006-08-17]. 
  26. ^ Arenholt-Bindslev, D; Jolanki, R; Kanerva, L. Diagnosis of Side Effects of Dental Materials, with Special Emphasis on Delayed and Immediate Allergic Reactions. Schmalz, Gottfried; Arenholt-Bindslev, Dorthe (编). Biocompatibility of Dental Materials. Springer. 2008: 352 [2014-03-05]. ISBN 9783540777823. doi:10.1007/978-3-540-77782-3_14. 
  27. ^ Habif, Thomas P. Clinical Dermatology. Elsevier Health Sciences. 2009 [2014-03-06]. ISBN 9780323080378. 
  28. ^ Yiannias, JA. Contact Dermatitis. Bope, Edward T.; Kellerman, Rick D. (编). Conn's Current Therapy 2014: Expert Consult. Elsevier Health Sciences. 2013 [2014-03-06]. ISBN 9780323225724. 
  29. ^ . doi:10.1016/j.foreco.2008.08.008.  缺少或|title=为空 (帮助)
  30. ^ Thorpe's Dictionary of Applied Chemistry 8 4th. Longmans Green. 1947. [页码请求]
  31. ^ N. Groom. New Perfume Handbook. Springer Science & Business Media, 1997 ISBN 9780751404036, pp. 184-186
  32. ^ Henley, Derek V.; Lipson, Natasha; Korach, Kenneth S.; Bloch, Clifford A. Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils. New England Journal of Medicine. 2007-02-01, 356 (5): 479–485. ISSN 0028-4793. PMID 17267908. doi:10.1056/nejmoa064725. 
  33. ^ Debboun, Mustapha; Frances, Stephen P.; Strickman, Daniel (编). Insect Repellents Handbook 2nd. CRC Press. 2014: 362. ISBN 1466553553. 
  34. ^ Kaddu, Steven; Kerl, Helmut; Wolf, Peter. Accidental bullous phototoxic reactions to bergamot aromatherapy oil. Journal of the American Academy of Dermatology. 2001, 45 (3): 458–61. PMID 11511848. doi:10.1067/mjd.2001.116226. 
  35. ^ Henley, Derek V.; Lipson, Natasha; Korach, Kenneth S.; Bloch, Clifford A. Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils. New England Journal of Medicine. 2007, 356 (5): 479–85. PMID 17267908. doi:10.1056/NEJMoa064725. 
  36. ^ Oils make male breasts develop. BBC News. 2007-02-01 [2007-09-09]. 
  37. ^ Carson, Christine F.; Tisserand, Robert; Larkman, Tony. Lack of evidence that essential oils affect puberty. Reproductive Toxicology. 2014, 44: 50–1. PMID 24556344. doi:10.1016/j.reprotox.2013.09.010. 
  38. ^ Scientific Committee on Consumer Products, Opinion on tea tree oil (PDF) (Report No. SCCP/1155/08), Directorate-General for Health and Consumers英语Directorate-General for Health and Consumer Protection: European Commission: European Union, 2008-12-16 
  39. ^ Bischoff, K.; Guale, Fessesswork. Australian Tea Tree (Melaleuca Alternifolia) Oil Poisoning in Three Purebred Cats. Journal of Veterinary Diagnostic Investigation. 1998, 10 (2): 208–10. PMID 9576358. doi:10.1177/104063879801000223. 
  40. ^ Menary, RC. Minimising pesticide residues in essential oils. Rural Industries Research and Development Corporation. 2008. ISBN 9781741517095. [页码请求]
  41. ^ Bone, Kerry. Principles and Practice of Phytotherapy: Modern Herbal Medicine. Elsevier. 2000: 453. ISBN 978-0-443-06992-5. 
  42. ^ Nordin, S.; Broman, D. A.; Olofsson, J. K.; Wulff, M. A Longitudinal Descriptive Study of Self-reported Abnormal Smell and Taste Perception in Pregnant Women. Chemical Senses. 2004, 29 (5): 391–402. PMID 15201206. doi:10.1093/chemse/bjh040. 
  43. ^ Dweck, AC. Toxicology of essential oils reviewed (PDF). Personal Care. September 2009. 
  44. ^ International Organization for Standardization. ISO 4720:2002 Essential oils – Nomenclature. [2009-04-23]. 
  45. ^ International Organization for Standardization. 71.100.60: Essential oils. [2009-06-14]. 


  • Baser, K.H.C. & G. Buchbauer. Handbook of Essential Oils: Science, Technology and Applications. CRC Press, Boca Raton, London, New York. 2010. ISBN 978-1-4200-6315-8. 
  • Schnaubelt, Kurt. Advanced Aromatherapy: The Science of Essential Oil Therapy. Healing Arts Press. 1999. ISBN 0-89281-743-7. 
  • Sellar, Wanda. The Directory of Essential Oils Reprint. Essex: The C.W. Daniel Company, Ltd. 2001. ISBN 0-85207-346-1. 
  • Tisserand, Robert. Essential Oil Safety: A Guide for Health Care Professionals. Churchill Livingstone. 1995. ISBN 0-443-05260-3.