Julia Lawless - Encyclopedia of Essential Oils - The complete guide to the use of aromatic oils in aromatherapy, herbalism, health and well-being.

Turpentine: 20 mins

Eucalyptus and thyme: 20–40 mins

Anise, bergamot and lemon: 40–60 mins

Citronella, pine, lavender and geranium: 60–80 mins

Coriander, rue and peppermint: 100–120 mins

It is therefore important to recognize that essential oils have three distinct modes of action with regard to how they inter-relate with the human body: pharmacological, physiological and psychological. The pharmacological effect is concerned with the chemical changes which take place when an essential oil enters the bloodstream and reacts with the hormones and enzymes etc; the physiological mode is concerned with the way in which an essential oil affects the systems of the body, whether they are sedated or stimulated, etc; the psychological effect takes place when an essence is inhaled, and an individual responds to its odour. With relation to the first two points, aromatherapy has a great deal in common with the tradition of medical herbalism or phytotherapy – in other words, it is not simply the aroma which is important but also the chemical interaction between the oils and the body, and the physical changes which are brought about.

The practice of aromatherapy could be seen as part of the larger field of herbal medicine, since the essential oil is only one of many ways in which a plant can be prepared as a remedy. Since all essential oils are derived directly from plants, it can be valuable to see them within a botanical context rather than as isolated products. In some ways the use of aromatic oils for therapeutic purposes benefits from being placed within a herbal context not only because it gives us further insight into their characteristics, but because the two forms of therapy are not synonymous, but complementary.

Growing and storing herbs: the woman is scenting the linen chest; from Das Kerfiterbuch oder Herbarius , 1534

Although most plants which yield essential oils are also used in medical herbalism, it is important to distinguish the therapeutic qualities of a particular oil from those of the herb taken as a whole or prepared in another manner. German chamomile, for example, is used extensively in the form of a herbal preparation such as an infusion, tincture or decoction, apart from being utilized for its volatile oil. Chamazulene, a major constituent of the oil, helps to account for the herb’s age-old reputation as a general relaxant and soothing skin care remedy, due to its pain-relieving, antispasmodic, wound-healing and anti-inflammatory activities. For the treatment of nervous conditions, insomnia and dermal irritation or disease, the essential oil is both useful and effective. But although the aromatic principle of the plant plays a central role in its overall character, the herb also contains a bitter component (anthemic acid), tannins (tannic acid), mucilage and a glycoside among other things. The overall effect of the herb is the result of the action of all its pharmacologically active constituents which in the case of chamomile or Matricaria includes the astringency of the tannins and the stimulation of the bitters. The volatile oil is, of course, less concentrated in the form of an infusion, tincture or decoction, the potency of the oil is reduced (and inherently the safety margin increased), thus making the herbal preparation more suited to internal use.

Similarly with peppermint. Whilst the oil is eminently suited to the treatment of respiratory conditions as an inhalant, due in particular to its antispasmodic and antiseptic actions, for the longer-term treatment of digestive disorders it is better to use extracts from the whole herb, where the action of the volatile oil is supported by the presence of bitters and tannins. In addition, in herbal medicine, the effect of one herb is usually supported and backed up by combining it with others.

Neither is it correct to assume that the essential oil is always the most active or therapeutically useful part of a plant. For example, although meadowsweet contains an essential oil outstanding in its antiseptic strength (according to Cavel, 83.3cc of meadowsweet essence renders infertile 1000cc of microbic cultures in sewage, compared to 5.6cc of phenol per 1000cc), it also possesses several other valuable components, notably salicylic glycosides which are characterized by their excellent pain-relieving and anti-inflammatory qualities. Indeed, the familiar drug aspirin, being derived from salicylic acid, is named after this herb, its old country name being ‘spiraea’.

The kernels of the (bitter and sweet) almond tree are used to produce a fixed oil commonly known as sweet almond oil, which has a great many cosmetic uses. The kernels from the bitter almond tree, which are used to produce the essential oil which gives marzipan its characteristic taste, also contain cyanide, the well-known poison, in its unrefined form. This shows that there can be a great difference in the properties of a plant, even the same part of a plant, depending upon how it has been prepared.

As a general rule which is in line with the present-day aromatherapy ‘code of practice’, it is best to use essential oils as external remedies only. This is mainly due to the high concentration of the oils and the potential irritation or damage that they can cause to the mucous membranes and delicate stomach lining in undiluted form. There even seems to be some kind of natural order in this scheme, in that volatile oils mix readily with oils and ointments suited to external application, which are absorbed readily through the skin and vaporize easily for inhalation. When inhaled, they can affect an individual’s mood or feelings, and at the same time cause physiological changes in the body. Indeed, in a Japanese experiment carried out in 1963, it was found that the effects of essential oils on the digestive system were likely to be stronger if they were inhaled than if they were ingested. Herbs, on the other hand, yield up many of their qualities to water and alcohol which are appropriate for internal use but, lacking the concentrated aromatic element, they do not have the same subtle effects on the mind and emotions.

These are only superficial guidelines, for there are always exceptions to the rule. Plantain, for example, is an excellent wound-healing herb valuable for external use, although it does not contain any essential oil. Nor can we ignore the fact that a great many aromatic oils are used for flavouring our food and beverages and are consumed daily in minute amounts. Peppermint oil, for example, is used in a wide variety of alcoholic and non-alcoholic beverages, confectionery and prepared savoury foods, although the highest average use does not exceed 0.104 per cent. The mint oils, which include spearmint and cornmint, are also used extensively by the pharmaceutical and cosmetic industries in products such as toothpaste, cough and cold remedies, and as fragrance components in soaps, creams, lotions, as well as colognes and perfumes. In addition, cornmint is frequently used as the starting material for the production of ‘menthol’ for use in the drug industry.

It can be seen that the use of essential oils covers a wide and varied spectrum. On the one hand they share the holistic qualities of natural plant remedies, although it is true that some herbalists view essential oils in much the same light as they regard synthetic drugs, being a ‘part’ of the whole, rather than the entire herb. On the other hand, they play an active role in the modern pharmaceutical industry, either in their entirety or in the form of isolated constituents such as ‘phenol’ or ‘menthol’.

It is not the aim of this book to glorify natural remedies (some of which are in fact highly toxic) at the expense of scientific progress, nor to uphold the principles of our present-day drug-orientated culture, but simply to provide information about the oils themselves in their multifaceted nature.