By Danny Siegenthaler | Curated by Anita Felice

This article is presented as originally written. Additional context and research references have been included below to support and clarify key concepts in light of current understanding.

How Essential Oils Work in the Body

Aromatherapy makes use of essential oils. This 3-Part article will provide detailed insight into the use of essential oils in aromatherapy and how essential oils work in the body, mind, and broader aromatherapy practice.

We will look at:

a) Where essential oils come from
b) The way essential oils effect the mind and emotions (in Part II)
c) The way essential oils effect the etheric body or the physcho-spiritual level (in Part III)

Where Do Essential Oils Come From?

The odoriferous substances (essential oils) themselves are formed in the chloroplasts of the leaves where they combine with glucose to form glucides and are then circulated around the plant in this form. At certain times of the day or year they are stored in particular parts of the plant.

In some plants, the essential oils are produced by the secretory tissues, and in others they are combined with glycosides, and are therefore not detectable until the plant is dried or crushed, e.g.: Valerian.

Essential oils are considered to be an important part of the plant's metabolism: some have hormonal activity and others are a stage in some other process, e.g.: the oil found in the rind of the orange is a stage in Vitamin A synthesis.

Essential oils can be found in almost any part of the plant, in differing concentrations, depending on the plant itself, the time of day and year. They may be found in the roots (e.g.: Calamus and Valerian), flowers (e.g. Lavender Oil, Rose Oil), bark (e.g. Sandalwood Oil, Cedarwood Oil), fruits (e.g.: Lemon Oil, Cardamom Oil, Orange), berries (e.g. Juniper Oil), and leaves (e.g. Thyme Oil, Rosemary Oil, Sage).

Plants which contain essences must be picked at the correct time of day and in the correct season, and in particular weather conditions in order that a maximum yield of essential oils can be obtained. Soil and climatic conditions will also dictate the quality of the oils obtained.

Heavy, concentrated oils are called ABSOLUTES e.g.: Rose, Jasmine. Oils which are solid at room temperature and which must be warmed before use are called BALSAMS, e.g.: Benzoin and Camphor.

How Do Essential Oils Work?

Essential oils are known to have an effect on us in three different, but overlapping, ways:

a) On the physical body, both locally and systemically, via the lymphatic and blood circulation
b) On the mind and emotions via the Sense of Smell and the Limbic System
c) On the “Etheric Energy System” of the body via the energy vibration of the individual oils themselves

The Way Essential Oils Effect the Physical Body

When essential oils are applied to the surface of the body, either via massage, baths, compresses, creams or lotions, they will have an effect locally (i.e. the site at which they are applied), and systemically (i.e. throughout the body).

The systemic effect occurs when essential oils are absorbed through the skin into the lymphatic circulation, and they are then carried into the bloodstream.

Once the oils are circulating in the blood, they are carried to their TARGET ORGAN/S, where they exert a therapeutic effect on the specific tissues. Every essential oil has its own target organ, e.g. Juniper oil targets the urinary tract and kidneys in particular, with secondary effects on the digestive, respiratory and reproductive systems. Chamomile oil targets the nervous system via which it can then exert a broad effect on many other body systems, like the digestive tract for example.

Even when essential oils are inhaled only, such as in steam inhalation or diffusion for aromatherapy benefits, the oils are absorbed across the mucous membranes of the respiratory tract and lungs into the bloodstream, where they can travel throughout the body.

If essential oils are taken orally, their absorption through the mucosa of the stomach and into the blood is very rapid. Very few essential oils are actually ‘digested’, which is fortunate as their therapeutic principles may well be altered if this were the case.

The reason essential oils behave in this manner is due to the small molecular size and organic nature of their chemical composition.

Some Therapeutic Properties of Essential Oils

1. Antiseptic

All essential oils are to a greater or lesser extent antiseptic. This includes anti-viral, antifungal, anti-bacterial and general antimicrobial activity found in oils such as Lemon, Thyme, Tea Tree, Garlic, Eucalyptus, Cinnamon, Pine, Lavender and Sandalwood.

2. Anti-Inflammatory

Essential oils with this property help to ease inflammation. Symptoms include pain, redness, swelling, and reduced function of the tissue involved. Examples include Chamomile, Rose, Lavender, Sandalwood, Myrrh and Benzoin.

3. Cytophylactic

Restoration of tissue function and regeneration of cells is another property of essential oils. Oils such as Pine, Basil and Rosemary are noted for adrenal support; Jasmine, Cypress and Ylang Ylang for reproductive endocrine function; Lavender and Chamomile for skin regeneration.

4. Sedative

Essential oils may also affect the nervous system by producing relaxation, relieving pain and easing muscle spasm. Oils include Lavender, Neroli, Rose, Geranium and Ylang Ylang.

However, one of the most emphasized properties of essential oils is their antiseptic/antigenetic property. This is documented in Dr. Jean Valnet’s book, The Practice of Aromatherapy, which discusses the effects of specific oils in relation to microbes such as meningitis bacteria, staphylococcus and typhoid.

In the chapter “The Healing Power of Plants,” Valnet references the many ways in which essential oils can affect the physical body.

It is critical to your understanding of essential oil therapy to appreciate the ways in which essential oils may have both a supportive and preventive role in conditions involving microbial activity.

About the Author

Danny Siegenthaler is a doctor of traditional Chinese medicine and, together with his wife Susan, a medical herbalist and aromatherapist, has created natural skin care products through Wildcrafted Herbal Products to share their combined expertise.

Clarification Notes

Target Organ:
The concept of a “target organ” reflects traditional aromatherapy frameworks describing patterns of effect, rather than a defined mechanism in modern physiology.

Absorption & Systemic Effects:
Essential oil absorption through skin and inhalation is supported, though the extent and systemic distribution vary depending on compound, dose, and method of application.

Oral Use:
Internal use of essential oils is described in some traditional and clinical contexts but is not universally applied across modern aromatherapy practice.

Etheric / Energy System:
This reflects a traditional or holistic model of health and is not part of conventional biomedical frameworks.

Antiseptic Generalization:
Many essential oils demonstrate antimicrobial activity, though potency and spectrum vary significantly by oil and composition.

References

[1] Hammer, K.A. et al. (1999)
Antimicrobial activity of essential oils and other plant extracts
https://pubmed.ncbi.nlm.nih.gov/10583848/

What it shows:
Demonstrates antimicrobial activity across a range of essential oils.

[2] Carson, C.F. et al. (2006)
Melaleuca alternifolia (Tea Tree) oil: a review
https://pubmed.ncbi.nlm.nih.gov/16418522/

What it shows:
Reviews antimicrobial and biological activity of tea tree oil.

[3] Perry, N. & Perry, E. (2006)
Aromatherapy in the management of psychiatric disorders
https://pubmed.ncbi.nlm.nih.gov/16542083/

What it shows:
Explores effects of essential oils on mood and neurological response.

Disclaimer

For educational purposes only. Not medical advice. Consult a qualified healthcare professional before use, especially if you are pregnant.