Essential oils enjoy enormous popularity today, and their use has expanded from traditional aromatherapy into the area of internal ingestion. Despite the fact that on the internet and on social media we often encounter recommendations for the internal use of essential oils, the professional community takes a reserved stance towards this approach.
About this article
In this article we explain why internal use of essential oils in home aromatherapy is discouraged and present scientifically based arguments in this field. We go through the extreme concentration of essential oils, the toxicity risk of particular types, the lack of regulation and the specific risks of internal use — and at the end we sum up how to use essential oils safely.
The article also introduces the Tisserand Institute, whose recommendations are regarded as the professional standard in the international aromatherapy community.
Why we do not recommend internal use
- Extreme concentration
Essential oil in a bottle is 50–100 times more concentrated than in the original plant, which has fundamental implications for safe use.
- High bioavailability
When ingested, almost the entire dose enters the bloodstream — up to 95 %. That is a heavy load for the liver and a toxicity risk.
- Potentially toxic components
Carvacrol in oregano, thymol in thyme or cinnamaldehyde in cinnamon can irritate the mucous membranes and act hepatotoxically; wintergreen, with its methyl salicylate content, can cause severe poisoning even in a small amount.
- Insufficient regulation
Essential oils intended for internal use are not subject to strict regulation and no standardised dosages have been established for them.
- Safe methods do exist
Inhalation, topical application in dilution (massage blends 1–3 %, cosmetics 0.5–1 %) and aromatic baths via a solubiliser or emulsifier.
The figures at a glance
What is the Tisserand Institute and why it is important
The Tisserand Institute is an internationally recognised organisation founded by Robert Tisserand, one of the most important experts in essential oil safety. Robert Tisserand is the author of the first English-language book on aromatherapy, published in 1977, and co-author of the second edition of the publication “Essential Oil Safety”, which has become the gold standard for establishing safety guidelines in this sector.
The Tisserand Institute specialises in translating the latest scientific research into evidence-based education focused on the safety and benefits of essential oils. The organisation provides objective information based on scientific evidence, thereby helping to create safe standards for the use of essential oils across the industry. Its recommendations are regarded as the professional standard in the international aromatherapy community and are often cited by regulatory authorities and cosmetic manufacturers.
Concentration and potency
One of the key arguments against internal use of essential oils is their extreme concentration. Essential oil in a bottle is 50–100 times more concentrated than in the original plant. This fact has fundamental implications for safe use.
For illustration: one drop of peppermint essential oil corresponds to approximately 26–28 cups of peppermint tea. Such a concentration can cause irritation of the mucous membranes of the digestive tract, and with long-term use it may lead to damage to the liver or kidneys.
To produce 1 litre of peppermint essential oil, approximately 200–250 kg of fresh leaves are needed. In the case of lemon balm (Melissa officinalis), even 3–5 tonnes of plant material. This explains the high price of lemon balm oil as well as the extreme concentration of active substances.
The bioavailability of essential oils when ingested is up to 95 %, with inhalation approximately 50 % and with application on the skin only about 5 %. This means that when ingested, almost the entire dose enters the bloodstream — which is a heavy load for the liver and a toxicity risk.
Risk of toxicity
Many essential oils contain substances that are potentially toxic when used internally. The most high-risk include:
Oregano (Origanum vulgare)
- Contains high concentrations of carvacrol (60–80 %)
- Can cause mucosal irritation and hepatotoxicity
- Interacts with drugs metabolised in the liver
Thyme (Thymus vulgaris)
- Contains up to 54 % thymol
- High doses can cause irritation of the gastrointestinal tract
- Potentially hepatotoxic effects
Cinnamon bark (Cinnamomum verum)
- Contains 50–90 % cinnamaldehyde
- Can cause allergic reactions and damage to mucous membranes
- High risk of hepatotoxicity
Eucalyptus (Eucalyptus globulus)
- Contains 60–85 % 1,8-cineole
- Can cause respiratory problems and neurological symptoms
- Particularly dangerous for children
Wintergreen (Gaultheria procumbens)
- Contains up to 98 % methyl salicylate
- Even a small amount can cause severe poisoning
Tea Tree (Melaleuca alternifolia)
- Toxic when taken internally
- Cases of poisoning in children have been reported with only a few ml
The oils listed above are part of our range — for example red thyme, Eucalyptus Globulus, Wintergreen (Gaultheria) or tea tree — exclusively for aromatherapy and cosmetic manufacturing purposes, not for consumption.
Insufficient regulation and standardisation
Unlike pharmaceutical preparations, essential oils intended for internal use are not subject to strict regulation. There are no established standardised dosages, which leads to situations where consumers do not have sufficient information about safe amounts.
In the food industry, some components of essential oils are used as flavourings (GRAS — Generally Recognized As Safe), but these are highly purified substances used in micro quantities. This is fundamentally different from the use of common EO sold for cosmetics or aromatherapy. Labelling cosmetic EO as “suitable for consumption” may be in conflict with legislation.
Specific risks of internal use
Damage to the digestive system
- Burning sensation and irritation in the oral cavity
- Sudden vomiting and nausea
- Gastro-oesophageal reflux
- Damage to tooth enamel on direct contact
Hepatotoxicity
- The liver is the main organ responsible for the detoxification of essential oils
- Long-term or high doses may cause damage to hepatocytes, increased enzyme levels or acute hepatitis
Drug interactions
- Essential oils can significantly affect drug metabolism via the cytochrome P450 system
- This may lead to increased or decreased efficacy of medicines and to toxic levels
Neurological effects
- Dizziness and disorientation
- Convulsions at high doses
- Depression of the central nervous system
Safe ways to use EO
Inhalation
- Aromatherapy diffusers (electric or candle-based)
- Inhalation from a bowl of warm water
Topical application
- Massage blends (1–3 % concentration)
- Cosmetic products (0.5–1 % concentration)
- Always follow the limits and categories of use according to IFRA
Aromatic baths
- EO added to the bath always via a solubiliser or emulsifier, or in the form of bath salts
- Proper dilution minimises the risk of skin irritation
To dissolve essential oils in the water phase you can use, for example, Polyglyceryl-10 Laurate, solubiliser or Symbio solv clear plus; sea salt makes a good base for bath salts.
Conclusion
Internal use of essential oils represents a disproportionately high risk compared with the potential benefits. The extreme concentration of active substances, insufficient regulation and the possibility of serious side effects make this practice dangerous for the general public.
Internal use of essential oils should take place exclusively under the supervision of qualified healthcare professionals with appropriate knowledge of aromatherapy and essential oil interactions. In the European Union, essential oils are classified as food supplements only when they meet strict quality and safety criteria. Most essential oils available on the market, however, are not intended for internal use, and their sale for this purpose may be in conflict with legislation.
Even though many essential oils in our range are classified as food supplements, we do not recommend their internal use and we sell them exclusively for aromatherapy and cosmetic manufacturing purposes.
Frequently asked questions about essential oil safety
Practical questions about the concentration of essential oils, the most high-risk types, regulation and how to use them safely.
Why do you not recommend the internal use of essential oils?
Internal use represents a disproportionately high risk compared with the potential benefits. The reasons are the extreme concentration of active substances, insufficient regulation and the possibility of serious side effects — which makes this practice dangerous for the general public. It should take place exclusively under the supervision of qualified healthcare professionals with knowledge of aromatherapy and essential oil interactions.
How much more concentrated is an essential oil than the original plant?
Essential oil in a bottle is 50–100 times more concentrated than in the original plant. One drop of peppermint oil corresponds to approximately 26–28 cups of peppermint tea. To produce 1 litre of peppermint oil, approximately 200–250 kg of fresh leaves are needed, and in the case of lemon balm (Melissa officinalis) even 3–5 tonnes of plant material.
Which essential oils are the most high-risk when taken internally?
Oregano (carvacrol 60–80 %), thyme (up to 54 % thymol), cinnamon bark (50–90 % cinnamaldehyde), eucalyptus (60–85 % 1,8-cineole, particularly dangerous for children), wintergreen (up to 98 % methyl salicylate — even a small amount can cause severe poisoning) and tea tree, for which cases of poisoning in children have been reported with only a few ml.
Why is ingestion riskier than inhalation or application on the skin?
Bioavailability is what decides: up to 95 % when taken internally, approximately 50 % with inhalation and only about 5 % with application on the skin. When ingested, almost the entire dose therefore enters the bloodstream — which is a heavy load for the liver and a toxicity risk.
Are essential oils not used in the food industry as well?
In the food industry, some components of essential oils are used as flavourings (GRAS — Generally Recognized As Safe), but these are highly purified substances used in micro quantities. This is fundamentally different from the use of common EO sold for cosmetics or aromatherapy — labelling cosmetic EO as “suitable for consumption” may be in conflict with legislation.
So how should essential oils be used safely?
By inhalation (aromatherapy diffusers — electric or candle-based, or inhalation from a bowl of warm water), by topical application in dilution — massage blends 1–3 %, cosmetic products 0.5–1 %, always following the limits and categories of use according to IFRA — and in aromatic baths, where EO are always added via a solubiliser or emulsifier, or in the form of bath salts. Proper dilution minimises the risk of skin irritation.
Do you sell essential oils for internal use?
No. Even though many essential oils in our range are classified as food supplements, we do not recommend their internal use and we sell them exclusively for aromatherapy and cosmetic manufacturing purposes.
Diffusers, massage blends, cosmetic products and aromatic baths — for all the safe ways of using them you will find essential oils in the Handymade range.
