Essential oils: Are they safe as they sound?

Dr A. Bolin

Essential oils have been used for centuries for their healing properties, but is there a down side? Dr A. Bolin takes a look at the good, the bad and the sometimes ugly side of essential oils.

From relieving migraines to acne, it seems essential oils can help in almost any situation. And what’s more, they’re ‘natural’, so they must be safe – right? Well, that isn’t always the case. If ingested they can be toxic – even fatal, they can cause allergic reactions, and they can burn skin. Let’s take a closer look.

What are essential oils? 

Essential oils are derived from plants, leaves, flowers, fruits, bark and wood.  Different techniques exist to extract the oils, such as enfleurage (a process where animals fats are saturated in plant oils), cold-press or steam distillation to name a few.

Depending on the original substance, various oils are produced.  Examples of flower oils include rose, geranium, and jasmine.  A resin oil example is frankincense.  A fruit oil example is citrus oils and leaves can give rise to patchouli oil.  Bark or wood oils include sandalwood and cedarwood oils.  After various extraction methods, different oils may contain various chemical components such as terpenes, esters, aldehydes, ketones, alcohols, phenols, and oxides. So beware, they may be flammable!


How long have they been around?

Many civilisations have documented use of these oils for health benefits and beautification.  Indigenous tribes have long used various plant sourced derivatives for medicinal purposes.  Historically many cultures had knowledge of therapeutic benefits and utilized plant-derived products.  The Chinese documented medical applications of herbal medicine in ancient texts, the Egyptians integrated essential oils from complex beauty treatments to embalming rituals, Ayurvedic medicine was extensively recorded in India and Greek physicians such as Hippocrates wrote about medicinal attributes of plants etc.


Are they pure? 

Depending on the quality, quantity, and price of the essential oil.  Some cheaper oils are not pure and may have chemicals, contaminants or, a cheaper vegetable oil is added.


Can essential oils cause an allergic reaction or be unsafe?

Yes.  The European Federation of Essential Oils was founded to address documentation of allergies and legislation regarding safety.


How are essential oils used?

Some people use them topically, others inhale or vapourise them in a diluted form.  In some countries people ingest them. When use appropriately and in safe amounts the vast majority are regarded as safe, but if they are used in the wrong way or the wrong ones are swallowed there can be serious problems, including fatalities in children.

It is very important to bear in mind that some oils are not meant to be ingested.  According to Dr Justin Loden of the Vanderbilt University Medical Center’s Tennessee Poison Center in America “the rule of thumb in toxicology is ‘the dose makes the poison,’ so all essential oils are potentially harmful.”

“In children, poisoning typically occurs when they try to swallow the oil, but choke so that a little of it goes into the lungs, which causes pneumonia; it only takes less than half a teaspoonful to do that. This hazard applies to every essential oil,” Loden said in a university news release.


Topical exposure is also a problem in children he explained as their skin is thinner and can absorb dangerous amounts.

In both adults and children they can cause burns and allergic reactions. These are not signs of ‘detoxing’ as some therapists may suggest and should be treated by a doctor, the Altantic Insitute of Aromatherapy advises. It’s published a top ten list of things that have gone wrong when bad advice is given by therapists, including using tea tree oil to cure thrush, which resulted in chemical burns in a woman’s vagina.

Highly toxic essential oils include tea tree, eucalyptus, camphor, clove, lavender, thyme, and wintergreen oils. Many essential oils can cause symptoms such as agitation, hallucinations and seizures. Symptoms may also include chemical burns, breathing problems, liver failure and brain swelling, vomiting, nausea and diarrhea, among others.


If I had an allergic reaction how would I know?

If you experience a rash (dermatitis), itchiness, pain, urticaria (hives), difficulty breathing, nausea, vomiting and diarrhea, stop utilizing the essential oil immediately.  Make sure that you check with your healthcare provider as soon as possible.  Remember that it is possible to use the oil several times with no reaction, then later on to develop an allergy (delayed type hypersensitivity).  If you experience shortness of breath, head to a hospital emergency department immediately for an assessment.


Can they affect other medications I might be taking? 

It is possible for medications and essential oils to have an effect on each other (drug drug interaction). An example of this would be the metabolism of 5-FU (5-fluorouracil) which is a skin cancer medication and could be affected by peppermint/eucalyptus oils.


If you are on any medication it is always important to discuss any complementary medicine you may take including herbal medicine, traditional treatments and essential oils.


If I’ve had allergies before should I worry? 

If you are allergic to certain pollens, you might also experience a “cross-reaction” to an essential oil with some similar allergens.  For example, someone with a ragweed allergy may have an allergic reaction to chamomile oil.



  • Unless you have discussed the dose and concentration of specific essential oil choices with a healthcare provider, do not eat or drink essential oils
  • Make certain to note the concentration or dilution of the essential oil (normally 1-5%).
  • Certain essential oils may be meant to be used for inhalation but may be abrasive to topical application of the skin (i.e. thyme, oregano, clove, cinnamon bark).
  • Some oils cause a photosensitivity or increase your likelihood to sunburn, so avoid sun exposure (or tanning beds). An example would be citrus oils (i.e. bergamot, lemon, lime, orange, etc.)
  • Do not use oils on skin that has breaks in it or signs of infection.
  • The very young and the elderly may be more sensitive and at risk for reactions. Also, for pregnant women, not enough is known about the absorption of certain chemicals across the placenta so speak to your healthcare provider for more information.
  • Ensure that the oils are stored in a safe place where small children and pets cannot ingest them.
  • Take care not to use old oils and to respect expiry dates, as heat and light can change the chemical composition of the oil over time.
  • Before using a particular oil, consider doing a patch test beforehand
  • If you suspect an allergic reaction, contact your GP and consider consulting with a dermatologist or allergist for more information.


Further Resources:

Complementary medicine and alternative therapies can be useful and the right choice for many people.  It is important to be informed as to which essential oils might be the right match for you.  Tisserand and Balacs (1995) published a guide that can help delineate some of the risks and benefits of essential oils.

For more information on patch testing and allergies: