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Are essential oils dangerous?

Essential oils, obtainable without a prescription, are easily found in pharmacies, specialised shops or online. You will find them in little bottles and can be diluted, mixed or pure.

Essential oils have numerous virtues and benefits for your health and can show to be very efficient when the purpose is to cleanse or to sanitize. However, their natural and vegetal origin makes people often think, wrongly, that they are harmless. Their very high concentration can be the root of many problems.

Are essential oils then dangerous?


The symptoms and the seriousness of an intoxication through essential oils vary depending on:

– the type of exposure (ingestion, eye contact, …)

– the type of oil having been used and in what concentration (intoxication through pure essential oils is the most problematic)

– the quantity of oil ingested (1 drop, 1 mouthful …)

The neurological signs of an intoxication are: unrest or sleepiness, a feeling of being inebriated, problems of balance, hallucinations, awareness trouble

The main risk: sudden convulsions

Some other complications are possible: these can be respiratory (cough, throat irritation) or digestive (nausea, vomiting and abdominal pain, etc.)

The signs of an intoxication are generally obvious between 30 minutes and 4 hours after ingestion.

In the case of an essential oil accident, contact your doctor immediately or the Poison Control Centre on 13 11 26 for fast poisoning advice from pharmacists trained in toxicology. The poisons helpline is available 24 hours a day, 7 days a week.


Each of these substances has specific properties and therefore specific toxic risks, which makes a classification of the most toxic essential oils very complex.

For example, the EOs of sage, hyssop, cedar, eucalyptus and camphor are particularly dangerous if an overdose has been taken by a child because they can result in convulsions.

A certain group of patients is more sensitive to the toxicity of essential oils: in the case of asthma, epilepsy, allergies, in women who are pregnant or breastfeeding and in small children it is preferable to ask the opinion of a doctor before using essential oils.

1- In case of ingestion, symptoms can be numerous:

  • Irritation of the mouth mucous
  • Nausea
  • Vomiting
  • Diarrhoea

Studies (Source of this paragraph: Risques et bénéfices possibles des huiles essentielles (mars 2008-ecole EHESP)

In the United States, in 2006, the surveillance system (AAPCP) has identified 7377 cases of exposure to the ingestion of essential oils. Only 1.2% of these was the result of a normal usage of the product. The most incriminated EOs were tea tree, cinnamon and cloves. The consequences have been minor in 93%, major in 6.8% and major in 0.2%. it should be noted that no death was recorded as a result of ingestion of any of these oils and that, overall, there is no mention of any death in the literature. Scientific studies show that essential oils can present a certain toxicity but do not seem to be toxic by ingestion unless taken in large quantities and outside the classical framework of usage.

2- Skin contact

In case of skin contact with a pure or diluted oil (the intensity of irritation is largely dependent on the degree of dilution), skin irritations may appear:

-redness or a burning sensation, …

-allergic reactions with sensitive cases

Skin irritations and allergies have also been described by professionals using specific products in massage that may include essential oils.

To avoid such events, it is, of course, advised to apply a small quantity of very diluted EO on a small area of skin and observe the reaction (elbow crease test).

They also increase the skin’s photosensitivity: EOs containing citrus are considered as particularly photo-sensitive and are often likely to be the result of blisters, strong burns, sometimes so strong that they are irreversible. Their skin application is therefore not recommended 8 hours prior to sunbathing.

In case of eye contact, vision problems and damage to the cornea are possible. Such lesions are reversible.

3- Respiratory tract

The inhalation of vapours can sometimes trigger a slight irritation of the upper respiratory tract.



In case of ingesting essential oils, one can first rinse one’s mouth and have a few mouthfuls of water to drink. You must not make the person vomit nor give it milk to drink. Vomiting would bring about a false deglutition and cause serious respiratory troubles if breathed into the lungs.

⊗ Beware: spontaneous vomiting could occur.

To go to the hospital and remain there for observation could be necessary in the case of important ingestion or there is a risk of convulsion.

2-Skin contact

In case of contact with the skin, apply as soon as possible a vegetable oil in large quantity on the concerned area and mop up the surplus with a tissue then wash with water and soap and rinse abundantly.

⊗ If symptoms occur (redness, irritation, … ), contact your general practitioner.

3-Eye contact

In case of eye contact, it is essential to rinse the eye immediately with tepid water for at least ten minutes.

⊗ If irritation symptoms persist one hour after the rinsing (red-eye, irritation … ), contact your general practitioner.

4-Respiratory tract

In case of inhalation of vapours, take the person out of the room in order to allow the person to breathe fresh air.

⊗ If more serious respiratory symptoms arise, you will require medical assistance.

Other precautions:

They are not recommended during pregnancy or when breastfeeding

pregnant not allowed

Some oils can go through the placenta and constitute real dangers for the health of the unborn child while others can be the cause of a hormonal imbalance for the breastfeeding mother. Therefore, you should ban the use of essential oils orally.


Danger for toddlers and babies

infant not allowedToddlers and babies as they have a much finer skin than adults, don’t use pure.

The strong concentration of EOs is not adapted for your children, always consult a health professional before using essential oils with children. Therefore, you should always strongly dilute and never give them orally since the ingestion of some oils could be fatal.

To be banned are eucalyptus, rosemary and peppermint, as these could slow down the child’s breathing, even in some cases stopping it altogether if there are some respiratory problems present already. Floral waters are strongly recommended.

Beware of medicine interactions

When following a long-term medical treatment, it is paramount to check that the EO you are using does not interfere with your medication.

Pets and EOs

pet not allowedThe body functions of pets are very different to ours. They have for example a much stronger and more sensitive sense of smell than we do.

EO can be very toxic for cats and dogs, they may be the cause of trembling or vomiting and, in some cases, be responsible for the failure of vital organs; so be careful if you use them for treating fleas or wounds.

Good practice

1- Chemical groups with hazards

Ketones: they present a neuro-toxicity and an abortive risk

For example: camphor (or borneone) has antalgic properties, muscle relaxant and respiratory decongestant. It is one of the most neuro-toxic ketones.

⊗ Precaution:

  • Forbidden for babies under 30 months of age or for people suffering from epilepsy,
  • Not advised for children under the age of 6.

Phenols: present a dual risk of toxicity for both skin and mucous (dermo-causticity) and for the liver (hepatoxicity).

⊗ Precaution: do not use by rectal route, only very diluted by dermal route, while the oral route (in capsules or oleo-capsules) will be the most effective. In the case of a prolonged treatment, in order to avoid any hepatoxicity, it will be necessary to take these EOs in regressive doses and follow the treatment for a maximum of 10 days. Beyond such time, the liver may express some difficulties.

Monoterpenes: (all species of pine and fir, juniper) present a risk of nephrotoxicity (inflammation of the nephrons) if used long-term. But if there are no problems, these EOs have a respiratory action and we should not ingest them.

Cineol in the group of oxides is a molecule that can bring on convulsions. Found in general in all EOs with a strong respiratory impact (eucalyptus radiata and globulus, ravintsara, niaouli, …). Depending on the % of cineol contained in the EO, it will have a more or lesser risk of toxicity and could or couldn’t be used with a child for example.

2- Duration of use

clockToxicity can also show if an EO is used daily without a break. We call these breaks “therapeutic windows” and have the purpose of allowing the body to get rid of active elements. When a treatment has been recommended that lasts several months, the patient should only use the EO 5 days out of 7 or 3 weeks out of 4.

3- Dilution to improve tolerance

EOs are very effective (in most cases) when diluted in a vegetable oil. This dilution allows a slowing down of the absorption and improves the dermal tolerance. It is essential to do so with a certain number of EOs that are particularly irritating (all essences of citrus and conifers) and it is paramount for all EOs containing phenols (counter-indicated on the skin and mucous as it could cause severe burns), these have to be diluted to less than 10% in a VO.

Accident prevention

  • Close the bottles firmly
  • Keep the bottles out of reach of children
  • Do not use with children under the age of 3
  • Do not place diffusers of essential oils in reach of children
  • Bottles of essential oils can sometimes look like medication bottles (ex: eye drops). Keep them separately
  • Keep EOs away from air and light: a certain deterioration in a product may have an allergic reaction. It is the case for tea tree EO for example
  • Do not decondition products (keep them in their original packaging)
  • Do not remove labels on bottles

In short

EOs are overall toxic if ingested. Some are toxic after repeated exposure. The risk becomes greater if you use them pure.

If we keep in mind all these toxic effects, using EOs in perfect security is only a question of choice:

What oil?

What dosage?

For how long?

And by which route?

Like for any medication, there is for any EO a balance between its benefits and the possible risk of usage that must be considered depending on each person and/or situation. And don’t forget to talk to your doctor!


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