Aromatherapy and Essential Oils (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - General Information
Aromatherapy is a derivative of herbal medicine, which is itself a subset of the biological or nature-based complementary and alternative medicine (CAM) therapies. Aromatherapy has been defined as the therapeutic use of essential oils from plants for the improvement of physical, emotional, and spiritual well-being.
Essential oils are volatile liquid substances extracted from aromatic plant material by steam distillation or mechanical expression. Oils produced with the aid of chemical solvents are not considered true essential oils, because the solvent residues can alter the purity of the oils themselves and lead to adulteration of the fragrance or to skin irritation.
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Essential oils are made up of a large array of chemical components that consist of the secondary metabolites found in various plant materials. The major chemical components of essential oils include terpenes, esters, aldehydes, ketones, alcohols, phenols, and oxides, which are volatile and may produce characteristic odors. Different types of oils contain varying amounts of each of these compounds, which are said to give each oil its particular fragrance and therapeutic characteristics. Different varieties of the same species may have different chemotypes (different chemical composition of the same plant species as a result of different harvesting methods or locations) and thus different types of effects.
Synthetic odors are often made up of many of the same compounds, which are synthesized and combined with other novel odor-producing chemicals. Most aromatherapists believe that synthetic fragrances are inferior to essential oils because they lack natural or vital energy; however, this has been contested by odor psychologists and biochemists.
Aromatherapy is used or claimed to be useful for a vast array of symptoms and conditions. A book on aromatherapy in children suggests aromatherapy remedies for everything from acne to whooping cough. Published studies regarding the uses of aromatherapy have generally focused on its psychological effects (used as a stress reliever or anxiolytic agent) or its use as a topical treatment for skin-related conditions.
A large body of literature has been published on the effects of odors on the human brain and emotions. Some studies have tested the effects of essential oils on mood, alertness, and mental stress in healthy subjects. Other studies investigated the effects of various (usually synthetic) odors on task performance, reaction time, and autonomic parameters or evaluated the direct effects of odors on the brain via electroencephalogram patterns and functional imaging studies. Such studies have consistently shown that odors can produce specific effects on human neuropsychological and autonomic function and that odors can influence mood, perceived health, and arousal. These studies suggest that odors may have therapeutic applications in the context of stressful and adverse psychological conditions.
Practitioners of aromatherapy apply essential oils using several different methods, including (1) indirect inhalation via a room diffuser or drops of oil placed near the patient (e.g., on a tissue), (2) direct inhalation used in an individual inhaler (e.g., a few drops of essential oil floated on top of hot water to aid a sinus headache), or (3) aromatherapy massage, which is the application to the body of essential oils diluted in a carrier oil. Other direct and indirect applications include mixing essential oils in bath salts and lotions or applying them to dressings. Different aromatherapy practitioners may have different recipes for treating specific conditions, involving various combinations of oils and methods of application. Differences seem to be practitioner-dependent, with some common uses more accepted throughout the aromatherapy community. Training and certification in aromatherapy for lay practitioners is available at several schools throughout the United States and United Kingdom, but there is no professional standardization in the United States, and no license is required to practice in either country. Thus, there is little consistency in the specific treatments used for specific illnesses among practitioners. This lack of standardization has led to poor consistency in research on the effects of aromatherapy, because anecdotal evidence alone or previous experience has driven the choice of oils, and different researchers often choose different oils when studying the same applications. However, there are now specific courses for licensed health professionals that give nursing or continuing medical education contact hours, including a small research component and information on evaluating/measuring outcomes.