Of course, internal use should be under the guidance of medical professionals. It is advisable to keep to a minimum of three essential oils, and often one, or two is sufficient. For some forms of treatment, different formulas will be given at different times of day. Otherwise, the following is a general rule of dosage.

Only safe (non-toxic, non-irritant, non-sensitizing) essential oils may be taken internally: straight (undiluted) under the tongue for fastest absorption into the bloodstream, mixed with a carrier vehicle (e.g., honey, vegetal oil); taken in the form of capsules (gelatin) or tablets (charcoal); or added to mineral water, tea, or other drinks. Of course, the highly irritant oils (i.e., thyme, cinnamon bark) should be avoided in the mouth as one drop undiluted can burn the mucus membrane tissue and cause an ulcer. Always check the safety data before using any essential oil to avoid injury. Most Aromatherapists cannot administer oils orally to clients (i.e., diagnose, treat or prescribe). This area is usually left to medical professionals.

Frequency: When taken internally, essential oils are rapidly excreted through the urinary system bound with glucuronic acid, through the skin by sweat glands and through the lungs. They usually pass through the body within three to four hours and sometimes as little as one half hour. Therefore, it is logical to take doses (drops) 3-4 times a day four hours apart, as Dr. Jean Valnet recommended. Preferably, the dose should be taken with food to reduce mucus membrane irritation and to insure slow, efficient assimilation.

Dosage: in general, essential oils are taken orally according to weight:
One drop (or less depending on safety data) per 25 kg (or 55.3 lbs) or 2-4 drops are taken 3 to 4 times a day, for a maximum period of four weeks or less, depending on the toxicity of the essential oil(s).

Two to three weeks of treatment is usually sufficient, and a week or less is usually adequate for acute conditions. Some conditions may only require one or two applications. For chronic cases, allow a week (of suspended usage) between courses of treatment for every two weeks of treatment given (for example, two weeks of treatment followed by one week off). Beware of chronic toxicity (hepatic, nephritic) possibilities over long periods of treatments. Obviously, the phenolic compounds in some essential oils can cause mucus membrane irritation, and some oils are oral toxins. Children and the elderly must receive lower doses and be treated sensibly. This method is best left up to professional medical personnel. Nevertheless, the Chart Safety Data section for each oil, as well as Safety Considerations chapter in this section must be consulted before any internal application.