The truth about essential oils (EOs—where to begin? It’s a dense, meaty topic that can be challenging to unpack because essential oils are complex—in more ways than one. Aside from being one of the most important natural products derived from plants for their various biological properties and medicinal benefits/uses, they’re used in many industries like  perfumery, cosmetics, feed, food, and beverages. But for the sake of this article – and you pros ;) – we’re going to make this primarily about EOs in relation to skin care. 


First, The Lay of the Land

When we think of EOs—we tend to imagine little dropper bottles of liquid essence you can find on the shelves of health food stores amidst adaptogenic herbs and superfood powders. Through the practice of aromatherapy, these substances can provide both physical and physiological benefits, while also offering a meaningful ritual of self-care. Lavender, lemon and bergamot essential oils can help relieve stress, anxiety, depression and other mood disorders. When inhaled, for example, scent molecules travel from the olfactory nerves and directly impact the emotional center of the brain (the amygdala). However, there still lacks a substantive body of evidence to support the impact of essential oils on human health. 

The rising popularity and prominence of EOs today largely stems from the fact that wellness and holistic-living practices have reached a pinnacle, driven by the growing concern around emerging viruses and the risks associated with disease. In fact, the global natural fragrances market exceeded $7.51 billion in 2018 and has been expected to grow at around a CAGR of 9% between 2019 and 2026 to reach $15 billion. 

In the beauty sphere, EOs have been heavily promoted recently via the clean beauty movement as an alternative to synthetic fragrances like phthalates (which are purported to be endocrine disruptors and appear on the ‘no-no’ lists of many established clean beauty retailers). But they have also been criticized by various influencers amid the anti-fragrance movement and the rising incidence of sensitive skin. Do the words allergic contact dermatitis come to mind? More on this later. 

Essential Oils 101

EOs are complex mixtures of aromatic and non-aromatic compounds, and are natural sources of biologically active ingredients due to their particular chemical composition. Fun fact: each essential oil can be composed of more than 100 single compounds. They also consist mainly of lipophilic (fat-loving), small and non-polar molecules and can penetrate the skin easily.

These highly concentrated extracts may come from various parts of any of the 2000 species of essential oil bearing plants (e.g. peppermint essential oil comes from the leaves while black pepper from the fruit). They’re made by steam distillation, expression (physical crushing), solvent extraction, microwave-assisted extraction, or enfleurage (the transfer of the essential oil from flower petals to fat). Steam distillation is the most common, while expression is used to obtain essential oils from the peels of citrus fruits (think, orange, lemon, etc.). Many of these processes can be quite costly

The Role of EOs in Cosmetics

Essential oils play a pivotal role in the cosmetics industry offering a multitude of benefits—from both a sensorial and functional point of view:

  • Possessing strong fragrant properties, they can enhance the sensorial experience of a product by masking the odor. For example, ingredients like surfactants can impart an unpleasant aroma in a formula. Common essential oils used as fragrances include citrus, lavender, eucalyptus, and tea tree. Aroma ingredients or ‘fragrance components’ like linalool, geraniol, limonene, citronellol, and citral, which come from different chemical classes that make up a major part of essential oils, are also widely used.
  • Act as natural preservatives due to their antimicrobial properties.
  • Offer skin benefits like anti-acne, anti-aging, and skin lightening due to their chemical composition/complexity of active compounds. For example, in the cosmeceutical industry, lemon and orange essential oils are often used in skin and hair care for their antiseptic properties, while orange essential oil can offer benefits associated with skin elasticity and firmness, scars, and stretch marks
  • Positively impact our well-being and satisfy important emotional needs.
  • Strengthen the ‘natural’ positioning of a brand or product. 

The Scoop on Safety

As with everything in beauty—nuance and context is everything – especially when it comes to safety. EOs are generally considered safe and nontoxic when used at low concentrations, but they also possess strong allergy potential. Research also indicates that natural fragrances are not safer than synthetic ones (from a contact allergy point of view).

Keep in mind there are many factors influencing contact allergy—including allergen concentration, frequency of application, individual level of sensitivity, previous allergic eczema, combination with other irritants or allergens, and dose/unit skin (which outlines that the risk of becoming sensitized becomes higher with exposure to high-concentration products applied to small areas of skin, versus low-concentration products spread over larger areas). A general rule of thumb: look for diluted concentrations of EOs preferably mixed with a carrier oil like avocado, grapeseed, coconut or jojoba. And when in doubt—patch testing can help detect and prevent adverse skin reactions.

Photosensitization may also occur from certain essential oils containing photoxic compounds like citrus peel oils (e.g., lemon, orange, bergamot) if applied in a high concentration to the skin and then exposed to sunlight. Skin reactions could vary from pigmentation, blistering to severe full-thickness burns. 

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Essential oil safety is monitored in a few different ways from a fragrance point of view. Rest assured there is a wealth of scientific data and risk assessment methodologies that the fragrance industry uses to ensure safety of products. 

The International Fragrance Association (IFRA) defines which essential oils and components represent a potential allergy risk—and determines the maximum concentration to produce safe cosmetic products. This process can be referred to as a quantitative risk assessment or QRA. Then there is the International Organization for Standardization (ISO), which works to improve the quality of the essential oil market by codifying the composition of each essential oil and standardizing requirements for labeling, transport, and marking. For example, rosemary essential oil would have an individual identification resembling “ISO1342:1988 for Rosmarinus officinalis L.”

Lastly, we can’t forget the Food and Drug Administration (FDA), which from a regulatory perspective for EOs is not that robust—largely because fragrances are regarded as cosmetic ingredients which don’t require approval. They also don’t have the authority to require allergen labeling for cosmetics, so it’s usually up to cosmetic manufacturers and brands to disclose that information.


So, there you have it—everything you need to know about essential oils. You made it through a lot of technical detail so pat yourself on the back! The important thing to remember is that EOs play an essential role in the cosmetics industry and there are many factors that can contribute to contact allergy. Not to mention EOs have been used for mental, spiritual and physical healing, positively impacting our mood, physiology, and behavior. It’s been a source of comfort and wellbeing for consumers historically so they’re not going anywhere anytime soon.