Guide to the Use of Essential Oils in Cosmetics

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Essential oils concentrate centuries-old virtues into just a few drops. They are included in cosmetic formulations not only for their fragrance, but also for the properties they bring to the skin. In this article, we look at what they are, how to use them correctly and — an equally important point — what precautions they require.

What are essential oils?

They are complex mixtures of low-molecular-weight volatile compounds, consisting mainly of lipophilic terpenes and terpenoids and aromatic phenylpropanoids. Their composition varies depending on the plant and the extraction method.

They are obtained from aromatic plants, extracted from flowers, leaves, roots, bark or fruit peel through different processes:

• Steam distillation, the most common method, used for lavender, geranium, rosemary and most aromatic plants;
• Cold pressing, used mainly for citrus fruits, whose essences would degrade with heat;
• Solvent extraction, for more delicate flowers such as jasmine, which cannot withstand distillation.

The substances obtained are insoluble in water. Essential oil is a natural extract in every sense: in the plant, it serves to protect it from pests and fungi.

They are extremely concentrated compounds — large quantities of plant material are needed to obtain a small amount — and are therefore much more potent than carrier oils such as hazelnut or almond oil, which are specifically used to dilute them.

Why are they used in cosmetics?

The best-known use is aromatherapy: when diffused into the environment or inhaled, some oils have an aroma that reaches the limbic system, the area of the brain linked to emotions, with a relaxing or revitalizing effect on mood.

For topical use, one rule is essential: pure essential oils should never be applied directly to the skin. They must always be diluted in a carrier oil. This is the single mistake that causes the most cases of contact dermatitis among people who purchase them over the counter for home use.

They are also chosen in cosmetics for sustainability reasons: they are a renewable plant-based resource of active molecules, with antioxidant properties and, in some cases, a natural preservative effect that reduces the need for other additives.

Some examples documented in the cosmetic literature: tea tree oil is among the most studied for its action against Cutibacterium acnes, the bacterium involved in acne; geranium essential oil, rich in linalool and geraniol, has astringent and balancing properties that are useful for combination skin.

Are essential oils good for the skin?

The honest answer is: it depends on the concentration and the individual.

Many essential oils are rich in antioxidants such as caffeic acid and rosmarinic acid, and this is a real advantage. But the same molecules that make them interesting — linalool, geraniol, limonene, citronellol — are also among the twenty-six fragrance allergens that European regulations require to be declared on the label when they exceed a certain threshold.

This is not merely a bureaucratic detail: it means that lawmakers consider them potential sensitizers. Applying pure or overly concentrated essential oils can cause irritation, sensitization, dryness and redness.

Two practical tips. First: choose products in which the concentration of essential oils remains low and a carrier oil is always present. Second: if you have sensitive or reactive skin, carefully consider fragranced products — and always test the product on a small area before full use. This applies to any new cosmetic, but especially here.

Some citrus oils are also photosensitizing: when applied before sun exposure, they can cause skin reactions. It is better to reserve them for evening or rinse-off products.

Essentia Spa: the LeLang selection

For the Essentia Spa line, we selected specific essential oils, always diluted in hazelnut oil or shea butter and used in controlled concentrations, alongside a neurocosmetic active ingredient.

• Mint: provides an immediate sensation of freshness, due to menthol’s action on the skin’s thermal receptors, and has a revitalizing effect on the skin’s tone.
• Geranium: astringent and balancing, useful for cleansing pores and maintaining the balance of surface sebum.
• Sage: contains rosmarinic acid and carnosic acid, two of the most studied antioxidants, which counteract the oxidative stress responsible for skin aging.
• Rosemary: stimulates superficial microcirculation and is rich in flavonoids and caffeic acid, with a toning effect.
• Roman chamomile: present in the massage oil, with a soft fragrance and a profile focused on the comfort of delicate skin.

You will find them in the line’s massage oil and body scrub, with slightly different selections: the blend is tailored to the application, more enveloping in the oil and more toning in the scrub.

The complete story of the line can be found in the article on Essentia Spa and well-being through the skin.

Frequently asked questions about essential oils

How do you dilute an essential oil correctly?

For topical use, the practical rule is to stay well below 1% on the face and around 1–2% on the body — just a few drops in a tablespoon of carrier oil. In formulated cosmetics, the dilution has already been calculated and verified.

Why do linalool and limonene appear on the label if they are natural?

Because European regulations require certain fragrance allergens to be declared above a specific threshold, regardless of whether they are natural or synthetic. It is mandatory transparency, not a sign of poor quality.

Are they suitable during pregnancy?

At cosmetic concentrations, the safety margin is broad, but some oils — including sage and rosemary — are traditionally discouraged. During pregnancy, your doctor remains the appropriate point of reference.

Is a fragrance-free product safer?

For skin with a history of fragrance-related contact dermatitis, yes, and it is a reasonable choice. For everyone else, a well-formulated product with low concentrations of essential oils is perfectly suitable for use.

How should they be stored?

In dark glass, protected from light and heat, with the cap tightly closed. They are volatile and oxidize: an oxidized oil is more irritating than a fresh one, which is one reason why old bottles forgotten in the bathroom should be replaced.

Can they be used on children?

On young children, essential oils should only be used in products formulated for their age group. Those rich in menthol and camphor should be avoided because of the risk of respiratory reactions.