Safety and Essential Oils

by Jade Shutes

With so much emphasis these days on safety and essential oils, it seems that the challenge isn’t really about “more safety” but rather how shall we relate to it? How shall we interpret it so that it makes sense in our practice or general use of essential oils? And how shall we find balance within the extremes that appear on social media?

Jade’s philosophy is that essential oils are safe. It seems simple enough, right? And yet, there are four important caveats:

  1. Essential oils are safe when selected appropriately for the individual or purpose of the product.
  2. Essential oils are safe when the appropriate method of application (body oil, steam inha-lation, baths, etc.) is chosen correctly for the individual or purpose of the product.
  3. Essential oils are safe when the correct dilution of the essential oil is used.
  4. Essential oils are safe when the individual has the appropriate level of knowledge and experience with each essential oil they are using.

Essential oils are powerful. They speak on multiple levels (physiologically and emotionally) to the human organism and are capable of wildly diverse yet complementary therapeutic actions (antispasmodic, anti-inflammatory, etc.). Humans co-evolved with aromatic and medicinal plants, which have been our allies as food, as shelter, in magic or ritual, as aromas and olfactory delight, and as medicine. We have a symbiotic relationship. But, like in all relationships, we must cultivate our inherent respect for their power and their potency and use them accordingly.

A Positive Approach: Essential Oil Safety

In his book Aromatica, Peter Holmes shares the idea of creating a positive context for essential oil safety. Inspired by his writing, we have adopted and modified his model to create three categories of essential oils for home use as well as for the aromatherapist.

I hope, like Peter Holmes, to inspire a new way of viewing and relating to the safety of essential oils—one through the lens of the knowledgeable, responsible, reflective, and empowered aromatherapist and essential oil therapist. There are three categories of essential oils:

Category 1: Mild Essential Oils

This category includes most essential oils commonly used at home and in practice. The essential oils in this category are considered to be generally safe and without risk of toxicity or accumulation, even when used over an extended period of time. Specific essential oils in this group may also have unique safety information (e.g., photosensitizer, irritant, etc.).

Mild essential oils
Most essential oils, including Cape Chamomile, Cardamom, Carrot Seed, Cedarwood, Roman Chamomile, German Chamomile, Citrus Oils, Cilantro, Clary Sage, Cypress, Fennel, Fir, Frankincense, Geranium, Ginger, Lavender, Lavandin, Melissa, Pine, Rose, Saro, Tea Tree, etc.

Category 2: Strong Essential Oils

This group of essential oils presents some potential or risk of toxic accumulation of certain components, regardless of method of application. The essential oils below should be used with caution. The main concern is for neurotoxicity (negative impact on the nervous system). Be cautious with dermal applications, be sure to dilute them, and avoid daily long-term application (>10-30 days).

Essential oils in this category are contraindicated (not appropriate for use) during pregnancy or while breastfeeding.

Strong essential oils

  • Sage (Salvia officinalis), ⍺-thujone, β-thujone and camphor
  • Rosemary ct. verbenone (Rosmarinus officinalis), verbenone
  • Hyssop ct. pinocamphone (Hyssopus officinalis), pinocamphone
  • Rosemary ct. camphor (Rosmarinus officinalis), camphor

Category 3: Powerful Essential Oils

Essential oils in this group can cause acute poisoning regardless of route of administration. The oral use of these essential oils should be avoided due to potential for liver and nervous system toxicity. These oils are best avoided unless you have received proper education and training on their use and application.

Powerful essential oils with potential for acute toxicity

  • Mugwort (Artemisia vulgaris), thujone
  • Sage (Salvia officinalis), thujone
  • Hyssopus officinalis NOT Hyssopus officinalis var. decumbens
  • Lavandula stoechas, thujone
  • Wormwood (Artemisia absinthium), thujone
  • Cedar leaf (Thuja occidentalis), thujone
  • Pennyroyal (Mentha pulegium), pulegone


Along with the categories above, it is important to also know any specific safety concerns for each individual essential oil you have. And because so many aromatherapy products are applied to the skin, be aware of potential skin reactions. The three main skin reactions are irritation, sensitization, and photosensitization.


Irritation is when a substance applied to the skin produces an immediate irritating effect. The appearance of the skin may be blotchy and red, and it may be painful or feel like it is burning to some individuals. The severity of the reaction will depend on the concentration (dilution) and the specific essential oil applied. Avoid using undiluted dermal irritants on the skin, and avoid using even diluted oils on inflamed, open, or damaged skin.

Skin irritating essential oils include cinnamon bark, citronella, clove bud, lemongrass, oregano, thyme ct. thymol, winter savory


Sensitization is either an immediate or, more commonly, a delayed allergic response that involves the immune system. Cinnamon bark (and to some extent, the leaf) and clove bud are good examples of essential oils that can cause both immediate and delayed sensitization responses. Delayed sensitization means that although there may be no reaction upon the first or even after several applications, eventually an inflammatory reaction occurs.

What does it look like on the skin? There will be a red rash or darker area of the skin (in darker color skin), reflecting damage caused by substances such as histamine released in the dermis due to an immune response.

The problem with sensitization is that once it occurs with a specific essential oil, the individual is most likely going to be sensitive to it for many years and perhaps for the remainder of his or her life. The best way to prevent sensitization is to avoid applying known dermal sensitizers to the skin.

Skin sensitizers include cinnamon bark; oxidized oils of pine, fir, and other conifers; all citrus essential oils


Photosensitization is a reaction to a substance applied to the skin that occurs only in the presence of UV light in the UVA range. Photosensitizing essential oils will cause burning or skin pigmentation changes, such as tanning, upon exposure to sun or similar light (ultraviolet rays). Reactions can range from a mild color change to deep weeping burns. Do not use or recommend the use of photo-sensitizing essential oils prior to going into a tanning booth or out into the sun for at least twelve hours after application.

Certain drugs, such as tetracycline, increase the photosensitivity of the skin, thus increasing the harmful effects of photosensitizing essential oils under the necessary conditions.

Photosensitizing essential oils include angelica root, bergamot, expressed lemon, expressed lime, and expressed bitter orange. Distilled or expressed grapefruit has a low risk for photosensitization.

These citrus oils are not photosensitizing distilled lemon, distilled lime, mandarin, bergamot FCF, sweet orange, yuzu (distilled or expressed).