10 minute read
This is Part Two of our Three Part series on Essential Oils.
Part One: Essential Oil Notes: A Complete Guide for Skincare and Soapmaking
Part Three: Flash Points of Essential Oils: The Science Behind Protecting Your Aroma (Coming soon)
Disclaimer:
The information on this page is provided for general education only and is not intended as medical, toxicological, or regulatory advice. Users are responsible for ensuring their own formulations comply with applicable laws and safety requirements. Individual reactions may vary. Always consult reliable technical documentation and conduct appropriate safety testing before use.
Essential oils are concentrated botanical extracts that offer powerful benefits in skincare formulations. However, their potency requires careful use. Understanding essential oil safety, sensitisers, and dermal limits is vital for both new and experienced skincare formulators especially when creating products for regulated markets like Australia.
Why Do We Need Safety Guidelines for Essential Oils
Essential oils are concentrated plant extracts, with yields typically between 0.02% and 2%. This means 1 kg of oil can require anywhere from 50 to 5,000 kg of plant material, depending on the species. As a result, even a small number of drops contains a high level of aromatic compounds, which is why proper dilution is important to help reduce the risk of irritation or sensitisation.
Irritation and redness are common when oils are applied undiluted or used at unsafe levels. Safety guidelines balance aroma and functional use with skin protection, setting evidence-based maximum usage levels to guard against photosensitivity, dermal irritation, and allergic reactions.
Key Safety Organisations and Standards
IFRA Standards
The International Fragrance Association (IFRA) develops voluntary global standards for fragrance safety. The latest 51st Amendment details restrictions and prohibitions for over 200 materials. IFRA standards account for aggregate exposure, the total of all fragrance contact a consumer might experience across products making modern limits safer than ever.
In Australia, IFRA standards are voluntary but represent the internationally recognised framework for fragrance safety. While not law, they are a method for demonstrating that fragrance ingredients are used at safe levels under AICIS and Australian Consumer Law.
Robert Tisserand Guidelines
Robert Tisserand’s Essential Oil Safety: A Guide for Health Care Professionals is one of the most widely used references for dermal maximum guidelines. It draws on toxicological and chemical data to translate scientific safety assessments into practical use levels for formulators and practitioners.
EU Cosmetics Regulations
EU cosmetic law, under European Commission regulation EU Cosmetic Regulation (EC) No 1223/2009, requires the declaration of specified fragrance allergens and restricts or prohibits certain fragrance substances based on safety assessments. These labelling and ingredient controls support product transparency and help consumers make informed decisions about fragrance exposure.
If you sell cosmetic products into the EU (including via platforms such as Etsy or your own website), you must comply with EU Cosmetic Regulation (EC) No 1223/2009.
Shop Essential OilsUnderstanding Sensitisers and Allergens
What Are Sensitisers?
A sensitiser is a substance that can trigger an allergic skin reaction after repeated exposure. Once sensitisation occurs, the immune system recognises the substance as foreign and can overreact on subsequent contact, leading to dermatitis, itching, or redness.
Sensitising compounds occur naturally in many essential oils. For example, geraniol — found in citronella, rose, geranium, lemongrass, and palmarosa — is a recognised fragrance allergen. Other aromatic compounds can become more sensitising as they oxidise when exposed to air, which is why correct storage and appropriate dilution are important for reducing risk.
The EU’s 82+ Fragrance Allergens
EU cosmetic law lists 82+ known allergens that must be included on product labels when exceeding regulated amounts:
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Leave-on products: > 0.001 % (10 ppm)
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Rinse-off products: > 0.01 % (100 ppm)
Many of these allergens occur naturally in essential oils, including compounds such as benzyl alcohol, benzyl salicylate, cinnamal, and farnesol. Allergen content varies by oil and batch, so it should be verified using supplier allergen declarations or GC-MS data rather than relying on general assumptions.
How Sensitisation Occurs
The risk of skin reactions increases with both concentration and frequency of exposure. Stronger blends and repeated use raise the chance of irritation or allergic sensitisation.
Undiluted essential oils should never be applied directly to the skin, especially on broken or irritated areas. As oils age - particularly citrus and other terpene-rich types - their aromatic compounds oxidise when exposed to air, forming by-products that are more likely to cause skin reactions.
How to Calculate Sensitisers in Your Formulations
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Collect Data: Obtain an allergen declaration or GC-MS report from your supplier showing the percentage of each fragrance allergen present in the essential oil.
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Find Essential Oil Total: Determine what percentage of essential oil your formula contains (e.g. 1 ml essential oil in 99 ml base = 1%).
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Calculate Individual Components: (Allergen % in essential oil) × (essential oil % in formula) = allergen % in finished product.
Example: Geraniol at 15% in geranium oil used at 2% → 0.15 × 0.02 = 0.003 = 0.3% geraniol in the finished product. -
Cross‑check with IFRA Maximum: Compare the calculated level with recognised safety guidance (such as IFRA standards or toxicological data) for your specific product category.
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Sum Across Oils: If multiple essential oils are used, add together the amounts of the same allergen from each oil to determine the total allergen level in the finished product.
Understanding Dermal Limits
What Are Dermal Limits?
Dermal limits refer to the maximum recommended concentration of an essential oil or aromatic compound for safe application to the skin. These limits are derived from toxicological data, chemical constituent analysis, and safety assessments used in cosmetic and fragrance regulation.
Why Dermal Limits Matter
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Consumer Safety: Helps reduce the risk of irritation, allergic sensitisation, and phototoxic reactions.
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Regulatory Compliance: Supports compliance with recognised safety frameworks such as International Fragrance Association standards and EU cosmetic safety assessments.
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Professional Credibility: Demonstrates a safety-first approach to formulation and responsible ingredient use.
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Formula Efficacy: Appropriate dilution allows essential oils to be used effectively without unnecessarily stressing the skin barrier.
Factors Affecting Dermal Limits
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Product Type: Leave-on products result in longer skin contact than rinse-off products and therefore require lower use levels.
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Area Applied: Smaller or more delicate areas (such as the face) generally require lower concentrations than larger body areas.
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Target Users: Lower concentrations are recommended for children, during pregnancy, and for individuals with sensitive or compromised skin.
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Oil Chemistry: Essential oils high in phenols or aldehydes, and those rich in oxidation-prone terpenes, typically require tighter dermal limits due to a higher risk of irritation or sensitisation.
General Dilution Guidelines for Beginners
This information is intended as a general guide only. Always do your own due diligence and research the specific essential oils you’re using, as safety limits and recommendations can vary by oil, supplier, and intended use. *These are not oil-specific dermal limits.
|
Product Type |
General EO Range % |
|
Facial leave‑on |
0.5 – 1 % |
|
Lip balm |
0.25 – 0.5 % |
|
Eye area |
0.1 % (use hydrosols instead) |
|
Body leave‑on |
1 – 2 % |
|
Rinse‑off formulas |
1 – 3 % |
|
Haircare |
0.5 – 1 % |
Phototoxicity: A Special Consideration
Some expressed citrus essential oils contain furanocoumarins — naturally occurring compounds that can increase the risk of phototoxic skin reactions when exposed to UV light.
Phototoxic Essential Oils and Typical Limits (leave-on products):
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Bergamot (expressed): 0.4 %
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Lemon (expressed): 2.0 %
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Lime (expressed): 0.7 %
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Grapefruit: 4.0 % *low-risk compared to other citrus oils.
To minimise risk, distilled or FCF (furanocoumarin-free) versions can be used (such as Bergamot FCF), which allow higher usage levels depending on product category. Products containing phototoxic oils should not be applied before sun exposure, and users should avoid UV light for at least 12–24 hours after application.
Best Practices for Safe Formulation
Storage
Keep oils in dark glass bottles, sealed, away from heat/light. Oxidised oils increase allergy risk.
Patch Testing
Apply a properly diluted sample to a small area of skin (such as the inner wrist or elbow) and observe for 24–48 hours for any signs of irritation or reaction. Patch testing does not replace formal safety assessment.
Documentation
Record essential oil percentages and calculated allergen levels for every formula. Maintaining these records supports regulatory compliance and product safety review.
Source Quality
Purchase essential oils only from reputable suppliers who provide GC-MS analysis and fragrance allergen documentation.
Measuring Correctly
Use accurate scales or calibrated volumetric tools for measuring essential oils — never rely on drops. Drop size varies by oil and dispenser and can lead to unsafe concentration errors.
TGA Compliance for Australian Formulators
TGA Compliance for Australian Formulators
In Australia, cosmetic products are regulated based on the claims made about them. Under guidance from the Therapeutic Goods Administration, products marketed with therapeutic claims may be classified as therapeutic goods and become subject to additional regulatory requirements.
Therapeutic-type claims include:
Heals, treats, cures, anti-inflammatory, antibacterial, antiseptic, or disease-related claims.
Essential oils may be described using cosmetic-appropriate language, but must not be promoted as healing, treating, or preventing medical conditions when sold as cosmetics.
Oils Requiring Special Caution
Very Low Dermal Limits (typical reference values for leave-on products):
- Massoia – 0.01 %
- Costus – 0.05 %
- Tagetes – 0.01 %
- Betel – 0.1 %
- Garlic – 0.1 %
- Rue – 0.15 %
- Saffron – 0.02 %
These oils contain highly irritating or sensitising constituents and require extreme dilution if used on skin.
Not Suitable for Cosmetic Skin Products:
Cade (unrectified), Camphor (brown), Elecampane, Fig Leaf absolute, Horseradish, Mustard, Pine (huon), Sassafras, Savin, Snakeroot.
These materials contain toxic, phototoxic, or carcinogenic constituents and are not considered appropriate for cosmetic skin formulations.
Essential oil safety isn’t restrictive; it’s foundational for responsible, successful formulation.
By understanding sensitisers, calculating allergen loads, and respecting dermal limits, you can craft effective, skin-friendly products that align with recognised international safety frameworks.
Start small, document thoroughly, and refine continuously. Your commitment to safe, sustainable creation not only protects users but also defines your professionalism as a formulator.
Shop Essential OilsComplete Essential Oil Dermal Limit Reference
Below is the comprehensive list of essential oils and their maximum dermal use levels, as verified from Robert Tisserand and IFRA standards.
The information presented here has been compiled with care from reputable industry sources, including IFRA Standards and Essential Oil Safety by Robert Tisserand and Rodney Young. While every effort has been made to ensure accuracy at the time of publication, essential oil safety limits may vary depending on supplier specifications, batch composition, product type, geographic regulatory requirements, and ongoing updates to scientific research.
Maximum dermal limits and usage recommendations are subject to change as new studies, safety assessments, and regulatory reviews are conducted.
This guide is provided for educational purposes only. Readers are strongly encouraged to conduct their own due diligence and consult current supplier documentation, Safety Data Sheets (SDS), IFRA certificates, and relevant regulatory guidance prior to formulation, manufacture, or commercial use.
| Essential oil | Latin name | IFRA Cat 4 max | Tisserand max (dermal) | Key safety driver | Dermal limit source |
|---|---|---|---|---|---|
| Lavender (true) | Lavandula angustifolia | Often not restricted in Cat 4; check batch certificate | ~1% conservative maximum for facial leave-on products | Oxidation of linalool/linalyl acetate increases sensitisation | Tisserand – Essential Oil Safety |
| Lemon (expressed) | Citrus limon | Phototoxic citrus restricted by furanocoumarins; many Cat 4 certs ≈ 2% | ~2% leave-on unless distilled/FCF | Phototoxic furanocoumarins (e.g. 5-MOP) | IFRA Standards |
| Bergamot (FCF) | Citrus bergamia (FCF) | Typically not restricted when bergapten removed; verify certificate | Up to ~5%; manage allergen load | Linalool/limonene oxidation (not phototoxic when FCF) | IFRA + Tisserand |
| Orange, Sweet | Citrus sinensis | Non-phototoxic; often pragmatically capped | ~2% typical practice | Oxidation-related irritation | Tisserand |
| Peppermint | Mentha × piperita | No universal Cat 4 cap; exposure-dependent | ≤1% general facial leave-on; up to 5% only for short-term, localised use | Menthol & 1,8-cineole irritation; strong cooling | Tisserand |
| Eucalyptus (cineole) | Eucalyptus globulus | No universal Cat 4 cap; category/exposure based | ≤1% facial leave-on; ≤2–3% body leave-on | 1,8-cineole irritation; mucosal sensitivity | Tisserand |
| Rosemary (CT cineole) | Rosmarinus officinalis | No universal Cat 4 cap; allergen-driven | ≤2% facial; ~3% body | Cineole-related irritation | Tisserand |
| Rosemary (CT camphor) | Rosmarinus officinalis (CT camphor) | No universal Cat 4 cap; check batch | ≤2% facial; ~3% body | Camphor/ketone irritation | Tisserand |
| Tea Tree | Melaleuca alternifolia | Not universally capped; ensure fresh oil | ~2% leave-on; up to 5% short-term targeted use | Oxidation markedly increases sensitisation | Tisserand |
| Rose Geranium | Pelargonium × asperum | Category-driven; allergens limit totals | ~2% typical | Citronellol/geraniol sensitisation | Tisserand |
| Geranium (graveolens) | Pelargonium graveolens | As above; check certificate | ~2% typical | Citronellol/geraniol | Tisserand |
| Patchouli | Pogostemon cablin | Often not restricted; verify certificate | Up to 5% | Generally well tolerated; oxidation caution | Tisserand |
| Vetiver | Chrysopogon zizanoides | Often not restricted; verify | Up to 5% | Low sensitisation; heavy sesquiterpenes | Tisserand |
| Ylang Ylang (complete) | Cananga odorata | Certificate-specific due to isoeugenol | 0.8–2%; ≤1% preferred for facial leave-on | Isoeugenol/benzyl benzoate allergens | Tisserand + IFRA |
| Lemon Myrtle | Backhousia citriodora | ~0.71% Cat 4 (example IFRA cert) | ≤0.5–0.7% | Very high citral content | IFRA + Tisserand |
| Frankincense (serrata) | Boswellia serrata | Often not restricted; verify | Up to 3–4% | Low sensitisation; oxidation check | Tisserand |
| Frankincense (carterii) | Boswellia carterii | Often not restricted; verify | Up to 3–4% | As above | Tisserand |
| Bergamot (expressed) | Citrus bergamia | ≤0.4% (phototoxic) | ≤0.4% unless FCF | Bergapten phototoxicity | IFRA |
| Lavandin | Lavandula × intermedia | Typically higher Cat 4 allowance; confirm | ~2% facial; higher for body | Camphor & oxidised allergens | Tisserand |
| Oregano | Origanum vulgare | Limited by phenolics | ≤1% leave-on | Carvacrol/phenolic irritation | Tisserand |
| Clary Sage | Salvia sclarea | Often not restricted; verify | ~4% | Generally well tolerated | Tisserand |
| Marjoram (sweet) | Origanum majorana | Often not restricted; verify | ~4% | Mild compared to oregano | Tisserand |
| Lemongrass | Cymbopogon citratus | ~0.71% Cat 4 (example cert) | ≤0.7% | High citral sensitisation | IFRA + Tisserand |
| Cypress | Cupressus sempervirens | Often not restricted in Cat 4; verify certificate | ~4% | General irritancy; terpene oxidation | Tisserands Essential Oil Safety |
| May Chang (Litsea) | Litsea cubeba | ~0.7% Cat 4 by citral | ≤0.7% | Citral sensitisation | IFRA + Tisserand |
| Melissa | Melissa officinalis | ~0.7–0.9% Cat 4 by citral | ≤0.9% | Citral sensitisation | IFRA + Tisserand |
| Thyme (CT thymol) | Thymus vulgaris | Phenolic-driven; very low | ≤1.3% | Thymol irritation | Tisserand |
| Cinnamon Bark | Cinnamomum verum | Very low; cinnamaldehyde-driven | 0.06–0.1% | Strong irritant/sensitiser | Tisserand |
| Clove Bud | Syzygium aromaticum | Eugenol-limited | ≤0.5% | Eugenol sensitisation | Tisserand |
| Basil (estragole CT) | Ocimum basilicum | Estragole-limited | ≤0.5% | Estragole concern | Tisserand |
| Lime (expressed) | Citrus aurantifolia | ≤0.7% | ≤0.7% | Phototoxic furanocoumarins | IFRA |
| Grapefruit (expressed) | Citrus paradisi | Often capped pragmatically | ≤2% | Variable FC content; oxidation | Tisserand |
| Bitter Orange (expressed) | Citrus aurantium | Phototoxic class | ≤2% | Phototoxic FCs | IFRA |
| Petitgrain | Citrus aurantium (leaf) | Typically higher; confirm | 2–4% | Allergen management | Tisserand |
| Neroli | Citrus aurantium (flower) | Typically higher; confirm | ~2% | Linalool/limonene allergens | Tisserand |
| Palmarosa | Cymbopogon martinii | Typically higher; confirm | ~2% | Geraniol sensitisation | Tisserand |
| Rose (Otto / Absolute) | Rosa spp. | Certificate-dependent | 0.6 % leave-on | Citronellol/phenethyl alcohol allergens | Tisserand |
| Jasmine Absolute | Jasminum officinale | Certificate-specific | 0.5–2% | Absolute allergens | Tisserand |
| Black Pepper | Piper nigrum | Typically allowed; warming | ~2% | Irritation/warming | Tisserand |
| Ginger | Zingiber officinale | Typically allowed | ~4% | Irritation/warming | Tisserand |
| Helichrysum | Helichrysum italicum | Often higher; confirm | 2–5% | Generally well tolerated | Tisserand |
| Sandalwood (E. Indian) | Santalum album | Often not restricted | Up to 5% | Well tolerated | Tisserand |
| Cedarwood (Atlas) | Cedrus atlantica | Often not restricted | Up to 5% | Mild profile | Tisserand |
| Hyssop | Hyssopus officinalis | Thujone-limited | ≤1% | Thujone/ketones | Tisserand |
| Oakmoss Absolute | Evernia prunastri | Very low (atranol) | ≤0.1% | Strong allergenicity | IFRA |
| Lemon Verbena | Aloysia triphylla | Low Cat 4 by citral | ≤0.9% | Citral sensitisation | IFRA + Tisserand |
| Fennel (sweet) | Foeniculum vulgare | Anethole-driven; certificate-specific | ≤2% | Anethole sensitisation | Tisserand |
| Fennel (bitter) | Foeniculum vulgare (bitter) | Estragole-driven; low | ≤1% | Estragole concern | Tisserand |
| Anise | Pimpinella anisum | Anethole-driven | ≤2% | Anethole sensitisation | Tisserand |
| Star Anise | Illicium verum | Anethole-driven | ≤2% | Anethole sensitisation | Tisserand |
| Niaouli | Melaleuca quinquenervia | Exposure-dependent | ~2% | 1,8-cineole irritation | Tisserand |
| Ravensara | Ravensara aromatica | Exposure-dependent | ~3% | General irritancy | Tisserand |
| Ho Wood | Cinnamomum camphora (linalool CT) | Often not restricted; verify | Up to 5% | Linalool oxidation | Tisserand |
| Ho Leaf | Cinnamomum camphora (linalool CT) | Often not restricted; verify | Up to 5% | Linalool oxidation | Tisserand |
| Camphor (white) | Cinnamomum camphora | Ketone-driven; low | ≤1% | Camphor neurotoxicity | Tisserand |
| Carrot Seed | Daucus carota | Typically moderate | ~1.5–2% | Sesquiterpene irritation | Tisserand |
| Cistus (Labdanum) | Cistus ladaniferus | Often not restricted; verify | ~2% | Resin acids | Tisserand |
| Elemi | Canarium luzonicum | Often not restricted | Up to 5% | Oxidation-related irritation | Tisserand |
| Copaiba Balsam | Copaifera spp. | Often not restricted | Up to 5% | Mild sensitisation | Tisserand |
| Balsam Peru | Myroxylon pereirae | Very low (IFRA restricted) | ≤0.4% | Strong allergenicity | IFRA + Tisserand |
| Balsam Tolu | Myroxylon balsamum | Allergen-driven; low | ≤0.4% | Benzyl benzoate/cinnamate | IFRA + Tisserand |
| Bay Laurel | Laurus nobilis | Eugenol-driven | ≤2% | Eugenol sensitisation | Tisserand |
| Bay (West Indian) | Pimenta racemosa | Eugenol-driven; low | ≤0.5% | Eugenol sensitisation | Tisserand |
| Juniper Berry | Juniperus communis | Often moderate | ~2% | Terpene irritation | Tisserand |
| Pine Needle | Pinus sylvestris | Often moderate; oxidation risk | ~2% | Oxidation-driven irritation | Tisserand |
| Spruce | Picea mariana | Often moderate | ~2% | Oxidation-driven irritation | Tisserand |
| Amyris | Amyris balsamifera | Often not restricted | Up to 5% | Generally mild | Tisserand |
| Peru Balsam (rectified) | Myroxylon pereirae (rect.) | Restricted | ≤0.4% | Strong allergenicity | IFRA |
| Galbanum | Ferula galbaniflua | Often moderate | ≤1% | Resin irritation | Tisserand |
| Angelica Root | Angelica archangelica | Furanocoumarins present | ≤0.8% | Phototoxic risk | Tisserand |
| Angelica Seed | Angelica archangelica (seed) | Lower phototoxicity | ≤1% | Mild irritation | Tisserand |
| Tansy (Blue) | Tanacetum annuum | Ketone-driven; low | ≤1% | Thujone/ketones | Tisserand |
| Wormwood | Artemisia absinthium | Thujone-driven; very low | ≤0.2% | Neurotoxicity | Tisserand |
| Mugwort | Artemisia vulgaris | Thujone-driven; low | ≤1% | Thujone/ketones | Tisserand |
| Rosewood | Aniba rosaeodora | Often not restricted | Up to 5% | Linalool oxidation | Tisserand |
| Spikenard | Nardostachys jatamansi | Often moderate | ≤2% | Sesquiterpene irritation | Tisserand |
| Costus Root | Saussurea costus | Extremely restricted | ≤0.05% | Strong sensitiser | Tisserand |
| Tagetes | Tagetes minuta | Very low (phototoxic) | ≤0.01% | Phototoxic thiophenes | Tisserand |
| Rue | Ruta graveolens | Very low | ≤0.15% | Phototoxicity | Tisserand |
| Garlic | Allium sativum | Very low | ≤0.1% | Sulphur compounds | Tisserand |
| Saffron | Crocus sativus | Very low | ≤0.02% | Potent actives | Tisserand |
- https://oshadhi.com/pages/essential-oils-a-to-z
- https://en.wikibooks.org/wiki/Complete_Guide_to_Essential_Oils/A_to_Z_of_essential_oils
- https://www.edenbotanicals.com/products/essential-oils-pure-therapeutic-grade/essential-oils-a-b.html
- https://www.vitacost.com/blog/list-of-essential-oils-and-their-benefits/
- https://www.scribd.com/document/910966575/Essential-Oils-Alphabetized-by-Common-Name
- https://en.wikipedia.org/wiki/List_of_essential_oils
- https://atlanticaromatics.com/essential-oils-a-z
- http://oilsofold.abmp.com/THEOS_YL_Oil_List_March_7_2013.pdf
