Aromatherapy is best defined as a complementary discipline of medicine that aims towards offering overall wellbeing using essential oils as healing agents. How aromatherapy works is not a mystery rather a pure science.  The essential oils, the healing agents of aromatherapy work on the body through 3 different pathways. While these pathways are often described as individual processes, in reality, each of the pathway interacts as well as influences the others within the body.

Essential oil pathways – how aromatherapy works on the body

• The cutaneous pathway – through the skin
• The respiratory pathway – through the membrane of lungs
• The olfactory pathway – through the neuro-endocrine system

In addition to the above 3, there is also the oral pathway, where aromatic medicines are used. Once the oils are within the body they work locally as well as systematically to offer healing & wellness.

The above flow diagram depicts a simplified design of how essential oils work in the body through the three different pathways. Essential oils can be taken in as liquid or as vapor. The liquid form can be either massaged on the skin or taken orally. Whereas, the vapor form must be inhaled.

On dermal application, the oil directly reaches the muscles & tissues on which it is applied, from there it reaches the joints. From muscle & tissues the active essential oil molecules go to the blood stream & to the other body tissues & organs.  Finally, they are excreted through the excretory organs. When taken orally, the oil molecules go to the intestine & from there to the blood stream. Finally, they are excreted.

In case of inhalation of essential oils, the oil molecules reach the lungs as well as the olfactory bulb present in the nose. From lungs, the molecules go to the blood stream & then to the body tissues & organs before being excreted through skin, kidney & lungs. Essential oils after reaching the system of olfaction through nose, impacts the brain which results in release of chemicals with strong positive mental & emotional impact.

In this case also, the oil molecules are excreted through skin, kidney & lungs following the same path. Now let us take a detailed look at each of the three pathways for an in-depth understanding of how aromatherapy works on the body as well as on the brain.    

The cutaneous pathway of essential oils

Massaging on the skin is considered as an ideal way of essential oil application. The skin is selectively-permeable in nature & it allows passage to water & lipid based substances, including essential & vegetable oils. The small sized molecules of essential oils & their bioactivity support penetration into the epidermis.

After travelling through the cells & intercellular spaces of the dermis they finally enter the lymphatic & blood circulation system. From there they are carried to the whole body along with blood. Being soluble in lipid these molecules are even able to cross the blood-brain barrier & that is how essential oils affect the brain quickly.

While a good part of the absorbed essential oil molecules adds up with the blood circulation system, some are absorbed by sebum & hair shafts, from where they enter the local microcirculation of the skin. Unlike orally taken medicines, essential oils entering into the body via skin do not have to pass through the liver, where they might be altered extensively.

After cutaneous application, the essential oil molecules are directly passed to the arterial circulation & from there throughout the body in their original state.  Finally, these molecules enter the venous circulation & are excreted through the kidney-urine pathway, as well as through lungs & skin.

The respiratory pathway of essential oils

On inhalation, the small molecules of essential oils are taken to the bronchial tubes along with air. There they stimulate the bronchial secretion which gives a moistening effect locally. The moisture rich environment facilitates better absorption of oxygen & also benefits in case of infection of lungs, throat or nose.

After reaching the bronchial tubes the essential oil molecules penetrate the mucous membranes & impact the local tissues according to their therapeutic properties. For example, in case of inhalation of essential oils with antispasmodic properties, the molecules affect the smooth muscles, thus helping with excess bronchial contraction.

After reaching the lungs, essential oil molecules facilitate the gaseous as well as nutrition exchange between the blood & the lung cells & also helps waste elimination from the lungs. In the next step, these molecules are absorbed into the blood & circulated throughout the body with arterial circulation. Finally, through venous circulation the molecules are taken back to the excretory organs from where they are eliminated by means of urine, sweat & breath.

The olfactory pathway of essential oils

How does aromatherapy work on the brain is a complex & important topic that has gained much interest in the recent times. The nose contains olfactory nerve receptors (cilia) & around 20 million nerve cells. As the essential oils are inhaled, the small molecules pass through the mucous membrane of the nostrils & stimulate the nerve receptors. This results into an electrochemical impulse that is passed to the olfactory bulbs present at the top of the nostrils.

The olfactory cells present at the nostrils are thought as the extensions of first cranial nerves which carry the stimuli of the odorant through the olfactory tract that branches to several sites in the brain. The olfactory system in its turn stimulates the amygdala & the hypothalamus, parts of the limbic system.

The hypothalamus affects the Central Nervous System, the endocrine system as well as the network of information exchange between the body cells. Any stimuli in the limbic system also affects the cerebrum (cortex) as well as the cerebellum & their functions. Hypothalamus influences the thalamus. The thalamus is related with emotions & memory. Hypothalamus also influences the pituitary gland through regulating factors.          

Essential oils affect the body through olfaction. Aromatherapy works on the brain & influences the central nervous system. The effect of essential oils triggers the release of endorphins from the limbic system & the peptide-cell receptor network, promoting a feeling of euphoria or sense of well-being.