Essential oils have been used for thousands of years across cultures, from ancient Egypt to traditional Chinese medicine to Ayurvedic practice. But the reason they have endured is not tradition alone. There is a real and well-studied mechanism behind how they work, and understanding it changes how you experience them.
If you have been following Eartha's Field Notes, you already know that we use only pure essential oils across all our products, and that we believe them to be categorically different from synthetic fragrance oils. This piece goes one step further and explains the science behind why essential oils affect the body and mind the way they do.
The two pathways
Essential oils work primarily through two mechanisms: inhalation and absorption. Most aromatherapy experiences involve both simultaneously, which is part of what makes them effective. But understanding each pathway separately helps you make more intentional choices about how and when you use them.
Inhalation: the fastest path to the brain
When you inhale the scent of an essential oil, the aromatic molecules travel through your nasal passage to the olfactory receptors at the top of the nasal cavity. From there, signals travel directly to the olfactory bulb, which connects immediately to the limbic system of the brain.
The limbic system is the part of the brain responsible for emotion, memory, and behaviour. It also has a direct relationship with the hypothalamus, which regulates the nervous system and controls the release of hormones. This is why a scent can shift your mood almost immediately. It is not a placebo effect or a matter of personal preference. The olfactory pathway is one of the fastest sensory routes to the brain, and the limbic connection means the effect is emotional and physiological at the same time.
Absorption: the skin as a pathway
The second mechanism is topical absorption. Essential oil molecules are small enough to penetrate the skin barrier and enter the bloodstream, where they can exert localised effects on the body.
This is the principle behind applying essential oils to specific areas. A blend containing peppermint or eucalyptus applied to the temples or neck can help with tension. Oils with anti-inflammatory compounds applied to sore muscles can support recovery. Oils with skin-supporting properties, such as frankincense or rosehip, can contribute to skin health over time when used consistently.
It is worth noting that essential oils should always be diluted in a carrier oil before topical application. The skin is permeable, and undiluted essential oils can cause irritation or sensitisation. A well-formulated product, like a body oil or a pulse oil, handles this dilution correctly so you get the benefit without the risk.
At Eartha, our body oils and pulse oils are formulated with this in mind. The essential oil blends are diluted in plant-based carrier oils at concentrations that are both safe for daily use and effective. You are not just getting the scent. You are getting the benefit of the oil working at a skin level as well.
When inhalation and absorption work together
The most complete aromatherapy experience happens when both pathways are active simultaneously, which is what occurs when you apply a scented body or hair oil after a shower.
As you warm the oil between your palms and apply it to your skin, you are inhaling the aromatic molecules at close range while the oil absorbs into the skin. The limbic response begins almost immediately through inhalation. The localised and systemic effects build gradually through absorption. The two mechanisms reinforce each other.
This is why the ritual of applying a body oil feels different from simply spraying a fragrance. The fragrance works on inhalation alone. The body oil works on both levels, which is a fundamentally different kind of experience.
Why pure essential oils matter for this to work
The mechanisms described above depend on the specific chemical compounds found in real essential oils. Terpenes, esters, alcohols, phenols, and ketones each have distinct interactions with the body's receptors and biological processes. These compounds are what make lavender calming, frankincense grounding, and bergamot uplifting.
Synthetic fragrance oils are designed to replicate the scent profile of natural oils, but they do not contain the same compounds. The smell may be similar. The physiological effect is not. You may enjoy the scent of a synthetic lavender fragrance, but it will not interact with your nervous system the way true lavender essential oil does.
This is the core reason Eartha uses only pure essential oils. A product built around synthetic fragrance cannot deliver the same quality of experience, no matter how pleasant it smells.
How Eartha's products work with these principles
Our product range is designed around both inhalation and absorption working together.
The body oils and hair oils deliver essential oil compounds through skin absorption during application, while the warmth of the skin and the proximity of application ensure inhalation happens naturally in the process.
The pulse oils are applied to pulse points, areas where the skin is thinner and blood flow is closer to the surface, which enhances both absorption and the release of aromatic molecules close to the face for inhalation.
The mood oils are formulated specifically for diffusion, maximising the inhalation pathway for mood and atmosphere.
Each format is intentional. Each works with the body's natural mechanisms rather than simply adding scent to a room or a routine.
If you would like to explore our range, the mood oils and pulse oils are a good place to begin experiencing both pathways together.
