An essential oil (EO) is a lipophilic and odorous extract, obtained by steam distillation, of a part (bark, leaves, flowers, fruits or roots) of an "aromatic" plant because it has the particularity of synthesizing an essence. Among the 800 000 plant species counted in the world, only 10% possess this specificity. Aromatic plants are, therefore, rare and remarkable plants.

Their use, for various purposes, appeared with the first civilizations. In Australia, 40,000 years ago, the Aborigines infused leaves of Melaleuca alternifolia, the famous tea tree, to relieve many ailments. In Asia (India and China) and all over the Mediterranean, they were used in many culinary, cosmetic or medicinal preparations. In ancient times, the Egyptians used it to embalm the corpses. The state of preservation of the recovered mummies highlights the antiseptic power of these plants. Hippocrates of Cos, Dioscorides, and Pliny the elder, Greek or Roman doctors, recommended essential oils in fumigations in order to sanitize infected organisms and putrid atmospheres. It was in Persia, a thousand years before our era, that Ibn Sina, called Avicenna, invented the still and the process of distillation which made possible the obtention of the first "real" essential oil.

Essential oils possess many medicinal properties that are used in aromatherapy. While their subtle and varied fragrances act, in olfactotherapy, on the psycho-emotional sphere.

In most cases, it is easy to understand the physiological impact of an essential oil on the organism because it is intimately linked to the presence of natural molecules, such as eucalyptol or 1.8 cineole, thymol, camphor or alpha terpineol.  An EO can contain up to 200 molecules belonging to identified chemical groups such as oxides, phenols, ketones or terpene alcohols (terpineols) which generate therapeutic activities. Studies, in vitro, in laboratory, but also, in clinical with human, have highlighted antiseptic, mucolytic, anti-inflammatory, analgesic, hormon-like qualities... but also tonic, soothing, balancing. Like many powerful active ingredients, some essential oils have side effects that need to be known before use. Seven adverse effects were identified:

1) dermocaustic (irritant and necrosis for skin and mucous membranes).

2) hypersensitizer (causes allergies),

3) photosensitizer (increases the sensitivity of skin to the sun),

4) neurotoxic (harmful to nervous system),

5) nephrotoxic (harmful to kidneys),

6) hepatotoxic (harmful to liver),

7) abortive (generates contractions for pregnant women).


For example, essential oils containing phenols are hepatotoxic and dermocaustic. However, a suitable concentration and dosage can mitigate these problems. In this demanding environment, health professionals recommend that these plant extracts are provided by qualified persons. However, the pharmaceutical specialties on the market allow a safe use of these natural and effective products.

The antibacterial, antiviral, antifungal and antiparasitic powers of certain EOs are no longer to be demonstrated. For several decades it has been observed that certain bacteria have acquired the faculty of becoming insensitive to antibiotics. Across the world, this phenomenon of antibiotic resistance has become a real public health problem. Studies carried out by teams of scientists from India and Serbia in 2011 and 2014 show that combining an essential oil to these drugs can potentiate the effect of these drugs. It is in this spirit, that in 2017, the Moroccan Professor Adnane Remmal developed a drug using the synergy between natural and synthetic. All these experiments confirm that some essential oils have a powerful antiseptic power. This property is particularly interesting for all winter diseases that may be of bacterial or viral origin (colds, bronchitis, etc ...). Taking EOs, as soon as the first symptoms appear (runny nose, scratchy throat ...) orally, applied locally or by inhalation can quickly heal a sick person.

Essential oils containing phenols (oregano, savory, thyme thymol or clove), aromatic aldehydes (cinnamon), terpene alcohols (thyme to linalool, tea tree, marjoram, etc.), oxides (eucalyptus globulus and radished, myrtle, niaouli, ravintsara ...) or terpenes (pine, citrus zest) are excellent antimicrobials. Moreover, it is important to realize that some of them present a real tropism, a fruitful affinity, for a given organ. For example, those rich in eucalyptol (oxide) possess activities adapted to the ENT and pulmonary sphere. They are antibacterial, antiviral but also expectorant, mucolytic and immunomodulating. They can be recommended by oral route, local application but above all by inhalation to disinfect and clear the nose, throat and bronchi in case of colds, rhinitis, nasopharyngitis or bronchitis. In aromatherapy, the first contact with an essential oil is olfactory thanks to their volatile nature. This characteristic and their disinfecting properties make them particularly valuable active ingredients for cleansing respiratory tracts.

A mixture of 3 to 5 essential oils gives excellent results to treat and relieve, pleasantly and naturally, many ailments. These synergies of plant extracts possess multiple therapeutic properties which it is useful to use, as first intention, in order to restore a state of "good health".

Pascale Gélis Imbert

Photo Pascale IMBERT
Pascale Gélis Imbert holds a Ph.D in Pharmacy specialized in phytotherapy and aromatherapy for over 20 years. She is a teacher, member of the scientific committee of the Observatory of Non-Conventional Medicines at the Faculty of Medicine of Nice, expert for companies and author of books on plants and essential oils. Her website:


  1. Analgesic: substance that alleviates or suppresses pain
  2. Antifungal: the antifungal substances treat diseases (fungal infections) due to the presence of fungi
  3. Antiseptic: a substance that helps to suppress or prevent the development of bacteria, viruses or other microorganisms.
  4. Hormone-like: is called substances that act as a hormone.
  5. Immuno-modulating: substance that rebalances the immune system.
  6. Lipophilic: miscible in oils and solvents that are apolar but immiscible with water.
  7. Mucolytic: substance which fluidifies mucus, substance secreted by the mucous membranes.