Essential oils: pleasant, potent, and sold with invented credentials
The bottle is a concentrate of a plant, which is the whole appeal and the whole problem.
6 min read · Published 7 September 2026
In one paragraph
Essential oils are steam-distilled or pressed plant concentrates, and a small bottle can represent kilograms of plant material. Inhaled, some of them plausibly shift mood a little, mostly through smell, memory and relaxation. What the marketing adds to that is unearned: 'therapeutic grade' is not a regulatory category, no agency certifies it, and the seals belong to the companies that trademarked them. The safety rules matter more than the claims, because a concentrate that smells like a spa can burn skin, poison a child at a few millilitres, and kill a cat.
What is in the bottle
Distillation strips the volatile aromatic compounds out of a plant and leaves everything else behind. The yield is small, which is why a bottle of rose oil costs what it costs, and it means the contents are many times more concentrated than anything the plant ever presented to you.
Concentration is the whole story. It is why the smell carries across a room from two drops, and it is why the safety section below is longer than the evidence section.
I use them. There is a bottle of frankincense on my shelf next to the copal, and I am not going to pretend a room smells the same without it.
What the evidence supports, at its actual size
Smell reaches the limbic system by an unusually short route, and odours attach to memory hard. A scent you associate with calm will calm you, which is a real effect with an ordinary explanation and no need for a special oil.
Beyond that, the trial literature is small studies with weak blinding, which is a hard problem when the intervention announces itself by smell. Lavender inhalation for anxiety before procedures shows modest effects in some trials. Peppermint oil for tension headache has some support. Tea tree oil has genuine antimicrobial activity in the laboratory and some clinical use for acne and fungal infection, and it is also the oil that sends most people to hospital.
The strongest result in this family is not aromatherapy at all: enteric-coated peppermint oil capsules have reasonable trial support for irritable bowel syndrome. That is a capsule designed to survive the stomach, taken as a medicine, and it tells you nothing about diffusing peppermint in a bedroom.
'Therapeutic grade' is a trademark, not a standard
No regulator defines therapeutic grade, medical grade, pharmaceutical grade or Grade A for essential oils. There is no test to pass and no body that certifies it. Where a seal exists, the company registered it themselves: doTERRA's Certified Pure Therapeutic Grade is a trademark they own, not an independent assessment.
That does not mean quality is uniform. Adulteration is real, oils are cut with cheaper oils or synthetics, and a batch-specific gas chromatography and mass spectrometry report from an independent lab is a meaningful thing to ask for. A phrase invented by the seller is not.
The safety rules, which are the actual content of this subject
None of these is precautionary hand-wringing; each one has case reports behind it
- Do not swallow them. Poison centres field thousands of essential-oil exposures a year, and in Australian data eucalyptus accounted for 46% of calls and tea tree 17%. As little as five millilitres of some oils causes seizures, liver injury or coma, and aspiration into the lungs is a distinct risk on top of that.
- Keep them locked away from children. They smell pleasant, the bottles are small, and children are most of the poisoning caseload. Child-resistant caps are not childproof.
- Dilute before skin contact. Undiluted oils cause chemical burns and sensitisation, and once you are sensitised to an oil the reaction tends to be permanent.
- Watch the citrus in sunlight. Bergamot and several cold-pressed citrus oils are phototoxic: on skin exposed to sun afterwards they cause burns and long-lasting pigmentation.
- Cats. Cats metabolise phenols poorly, and tea tree and eucalyptus in particular are toxic to them, including from a diffuser running in a room they cannot leave. Dogs and birds have their own sensitivities, birds especially.
- Pregnancy, epilepsy and infants each have their own contraindicated oils. This is a conversation with a pharmacist, not a search engine.
Where the money is
A large share of retail essential oil sales runs through multi-level marketing, where the person selling to you is also buying from the company and recruiting others. That structure rewards two behaviours: overselling health claims, and selling to friends and family who find it hard to say no.
It also produces the specific harm to watch for, which is oils recommended in place of medicine for infections, diabetes, cancer or a child's fever. Regulators in several countries have written to these companies about exactly that, repeatedly.
None of it makes the oils bad. It means the person telling you what an oil does may be paid by the answer.
How I use them, since I do
Diluted in a carrier oil for skin, a few drops in a diffuser for a room, and never anywhere near my mouth. I buy from suppliers who publish batch reports, and I do not believe the oil is doing anything to my cells.
What it is doing is marking a moment. The bergamot goes on when work stops. That is a scent cue attached to a boundary, and it works the way a candle or a bath works, which is not nothing and is not medicine.
If you want the practice framing rather than the chemistry, ritual baths and incense are the same idea from different directions.
Questions people ask
- Do essential oils do anything?
- Inhaled, they can shift mood modestly, mostly through smell, memory and relaxation, and a few have specific support: lavender for pre-procedure anxiety, tea tree as a topical antimicrobial. Enteric-coated peppermint capsules have reasonable evidence for IBS, but that is a medicine taken orally rather than aromatherapy. Claims that diffusing an oil treats disease are not supported.
- What does 'therapeutic grade' mean on an essential oil?
- Nothing official. No regulator defines or certifies the term, and seals such as Certified Pure Therapeutic Grade are trademarks owned by the companies that print them. A meaningful quality signal is a batch-specific gas chromatography and mass spectrometry report from an independent laboratory.
- Can you drink essential oils?
- No, unless a clinician has prescribed a specific preparation such as enteric-coated peppermint capsules. Essential oils are concentrates and ingestion is the main route to serious poisoning: a few millilitres of some oils can cause seizures, liver damage or coma, and aspiration into the lungs is an additional danger.
- Are essential oils safe around cats?
- Often not. Cats metabolise phenolic compounds poorly, and tea tree and eucalyptus are notably toxic to them, including through a diffuser in a room the cat cannot leave. Birds are more sensitive still. If animals share the space, ventilate, keep diffusing brief, and check any oil against a veterinary source first.
- Which essential oils are dangerous for children?
- Children are the largest group in essential-oil poisoning data, and eucalyptus and tea tree dominate the calls. Camphor, wintergreen, clove and thyme oils are also high risk. Store every bottle out of reach and locked if possible, never apply undiluted, and treat any suspected swallowing as an emergency call to a poison centre.
Santiago Garcias