There is much debate regarding the use of Essential Oils internally that the question of whether Essential Oils should be taken internally at all, and if so, how and in what amounts, is probably one of the most vexed in the whole of aromatherapy. We believe very strongly that essential oils should not be taken by mouth, but it is interesting to look at the context within which the two opposing views have arisen.

One school of thought, largely following the tradition of Marguerite Maury, holds that aromatherapy consists of external treatments only. This means massage, baths and inhalations as major methods of treatment, with some secondary use of essential oils in creams, lotions and other skin preparations. The effectiveness of these forms of treatment have been proved empirically over thousands of years, but in recent decades controlled experiments have demonstrated just how much and how quickly essential oils get into the blood-stream when applied to the skin. In addition, some oil will be inhaled, whatever the method of application, and inhaled oils also reach the blood­stream along with the oxygen and other gasses passing through the lungs. These two routes of entry both by-pass the digestive system, where the greatest potential damage from swallowing essential oils is likely. They also offer a faster way of getting essential oils into the bloodsteam, the digestive route being much slower.

The other tradition, which advocates the internal use of essential oils, arose in France where virtually all aromatherapists are fully qualified medical doctors, and this is an important factor to bear in mind. These therapists have a thorough knowledge of both the pharmacological aspects of essential oils and of human physiology. They also have access to a body of pharmacists trained in the dispensing of essential oil prescriptions, usually in the form of capsules, containing essential oil in a suitable excipient. (By way of comparison, we may consider the garlic capsules or 'perles' which are available at most chemists and health-food stores: these are made from essential oil of garlic diluted in a vegetable oil, usually soya or sunflower. Garlic oil alone, without the vegetable oil and the surrounding capsule would be far too potent to ingest.)

In Great Britain, America and other countries where only the tiniest minority of aromatherapists have a medical training, the situation is very different. If they suggest internal use of essential oils to their clients, without the years of training followed by their French counterparts, they risk serious harm to their clients, and in many countries will also be breaking the law. The general body of opinion now inclines to external use only, and even therapists who were using oils internally a few years ago are discontinuing this practise in the light of evidence about the risks. The International Federation of Aromatherapists specifically requires its members to use essential oils externally only.

The question of self-medication by some lay people is even more worrying. There are a number of websites and popular books available which suggest taking essential oils on sugar or honey, usually 3 drops at a time, but sometimes much more. As essential oils dissolve only in alcohol or other oils, the sugar does not dissolve the oil, but merely makes it palatable enough to swallow. (Perhaps we should let the fact that an undiluted essential oil is virtually impossible to swallow, act as a warning that they are not meant to be used in this way?)

Evidence collected by Robert Masson in France shows that undiluted essential oil can cause serious irritation, and even damage to the stomach lining. A further risk is that many people, particularly if they are not fully aware of the great degree of concentration of essential oils, think that if a little is good for them, a bit more will be even better! Three drops may appear too little to people accustomed to taking medication by the teaspoonful, and there is a dangerous fallacy that if a substance is natural, it is safe. If too much essential oil is taken, a great burden is placed on the organs of elimination, the kidneys and liver, as they try to remove them from the body.

In several cases where people have died as a result of essential oil overdoses, the cause of death has been massive destruction of the cells of the liver. Adding essential oils to fruit juice, herb teas, etc., is equally dangerous, as the oil will not dissolve in these water-based liquids, and the same risks to the stomach lining exist.