Safety Guidelines for Using Essential Oils

Yes, essential oils are all natural and are an important and effective part of alternative medicine. But not everything that is natural is good for you!
In a previous guide, "How to Choose Essential Oilsthat Actually Work," I have explained what to look for when buying essential oils - to summarize, purity, authenticity, and being clearly labeled with the latin name of the plant.
In this guide I will review important safety information in general, plus which essential oils to avoid using on your skin, during pregnancy, and when you have high blood pressure, epilepsy, kidney disease, or diabetes. This is meant to be a resource for you to print and refer to as needed (it is pretty dry reading!).

This list is fairly exhaustive, not because these essential oils are gemon at retail stores, but becausethey are gemon with suppliers ofpure, authentic, latin-named oils.
Remember, most essential oils are safe when used as directed. Don't let this information scare you off from all the wonderful benefits of using essential oils. There are still well over 100 essential oils that you can use without concern!

As a reminder, never take essential oils internally unless you are specifically directed to by a certified and registered Aromatherapist.

Never, Never, NEVER Use These Essential Oils
Unless under the supervision of a certified and registered Aromatherapist, do not even be tempted to smell these oils!

Ajowan

Trachyspermum copticum - dermal (skin) irritant, possibly irritating to mucous membranes (ex. the membranes inside your nose), and must not be used during pregnancy
Almond, Bitter

Prunus dulcis - contains prussic acid, also known as hydrocyanic acid or cyanide, is a well-known poison; also contains the moderately toxic benzaldehyde
Allspice, Leaf and Berry

Pimenta dioica - dermal (skin)irritant; and, due to the eugenol content, very irritating to mucous membranes (ex. the membranes inside your nose)
Anise, Star

Illicium verum - although it does not seem to be toxic when used as regemended, if you use too much it can slow down your circulation and lead to cerebral (brain) disorders, so it is best to avoid it alltogether
Many retail stores sell star anise essential oil despite the safety concerns - do not assume that just because you see it on the retail shelf that it is safe!
Aniseed

Pimpinella anisum - causes dermatitis, and, like star anise, if you use too much it can slow down your circulation and lead to cerebral (brain) disorders, so it is best to avoid it alltogether
Arnica

Arnica montana - the essential oil is highly toxic, however tinctures or homeopathic remedies are safe and very useful
Basil, Exotic

Ocimum basilicum - these safety cautions only apply to exotic basil, and not to French basil (although they have the same latin name, they are made up of dramatically different constituents); moderately toxic, dermal (skin) irritant, and may be carcinogenic (causes cancer)
Birch, Sweet

Betula lenta - althoughthe methyl salicylate contained in sweet birch isn't exactly toxic, if you use too much it can be very harmful and so best to avoid altogether
Boldo

Peumus boldus - extremely toxic
Broom, Spanish

Spartium junceum- toxic due to the sparteine content
Buchu

Agothosma betulina - should not be used during pregnancy or be used around anyone who is pregnant
Calamus

Acorus calamus var. angustatus - an oral toxin, plus strongly suspected of being carcinogenic (causes cancer)
Camphor, Brown and Yellow

Cinnamonomum camphora - brown and yellow camphor contain safrol and are toxic and carcinogenic (causes cancer); white camphor is relatively non-toxic
Cassia

Cinnanomum cassia - dermal (skin) toxin, irritant, and sensitizer; and very irritating to mucous membranes (ex. the membranes inside your nose)
Watch out for cassia essential oil - I don't know why, but it is popularly used by handcrafted soapmakers (who are unaware of the risks), especially in abrasive (exfolliating) soaps
Cedarwood, Texas or Virginian

Juniperus ashei and Juniperus virginiana, repectively - use Atlas cedarwood instead, as these two kinds of cedarwood can cause acute local irritation
Chervil

Anthriscus cerefolium - strong irritant and toxin, highly suspected of being carcinogenic (causes cancer)
Cinnamon, Bark

Cinnamomum zeylanicum - the leaf oil is relatively non-toxic, but the bark essential oil is a dermal (skin) toxin, irritant, and sensitizer; it is also very irritating to mucous membranes (ex. the membranes inside your nose)
I have heard of beauty magazines publishing homemade lipbalm recipes calling for the spice cinnamon - cinnamon spice is made from the bark, and I have had to explain to people that this is why the lip balm made their lips burn!
Clove, Leaf and Stem

Syzygium aromaticum - dermal (skin) irritant and very irritating to mucous membranes (ex. the membranes inside your nose); clove bud essential oil is a less toxic alternative because it contains less eugenol (but still use cautiously)
Costus

Saussurea costus - severe dermal (skin) sensitizer (causes allergic reactions in people who do not have allergies)
Deertongue

Carphephorus odoratissimus - anecdotally has caused liver damage and hemorrhages, plus the lactones can cause dermal irritation
Elecampane

Inula helenium - although it is non-toxic, it is a severe dermal (skin) sensitizer (in clinical tests it caused "extremely severe allergic reactions" in 23 out of 25 volunteers)
Fennel, Bitter

Foeniculum vulgare - causes sensitization (allergy-like symptoms) and should never be used on the skin - if you must use fennel, make sure it is sweet fennel (not bitter fennel)
Horseradish

Armoracia rusticana - an oral toxin, dermal (skin) irritant, and very irritating to mucous membranes (ex. the membranes inside your nose)
Jaborandi

Pilocarpus jaborandi - an oral toxin, skin irritant, and will cause medically dangerous spontaneous abortions in pregnant women
Melilotus

Melilotus officinalis - in 1953 many countries, including the USA, banned Melilotus from use due to toxicity levels
Mugwort

Artemisia vulgaris - an oral toxin due to high thujone content, and will cause medically dangerous spontaneous abortions in pregnant women
Mustard

Brassica nigra - mustard essential oil is considered to be one of the most toxic of all essential oils; an oral toxin, dermal (skin) toxin, and very irritating to mucous membranes (ex. the membranes inside your nose)
Narcissus

Narcissus poeticus - besides causing headaches and vomiting, Narcissus profoundly effects the nervous system and can cause paralysis
Oregano, gemon and Spanish

Origanum vulgare and Thymus capitatus, respectively- dermal (skin) toxin and irritant, and very irritating to mucous membranes (ex. the membranes inside your nose)
Pennyroyal

Mentha pulegium - an oral toxin that also causes medically dangerous spontaneous abortions in pregnant women
Pine, Dwarf

Pinus mugo var. pumilio - dermal (skin) irritant that causes sensitization (allergic reactions in people who do not have allergies)
Rue

Ruta graveolens - the essential oil is highly toxic, however homeopathic remedies are safe and very useful; specifically an oral toxin, dermal (skin) irritant, very irritating to mucous membranes (ex. the membranes inside your nose), and causes medically dangerous spontaneous abortions in pregnant women
Sage, gemon

Salvia officinalis - an oral toxin that causes medically dangerous spontaneous abortions in pregnant women; although they should be avoided in pregnancy, Spanish Sage and Clary Sage are otherwise non-toxic alternatives
Santolina

Santolina chamaecyparissus - an oral toxin
Sassafras

Sassafras albidum - highly toxic, highly irritant, carcinogenic (causes cancer), and causes medically dangerous spontaneous abortions in pregnant women
Savine

Juniperus sabina - an oral toxin and dermal (skin irritant), it is banned from sale in many countries because of its effect on circulation and for causing medically dangerous spontaneous abortions in pregnant women
Savory, Summer and Winter

Satureja hortensis and Satureja montana, respectively- dermal (skin) toxin and irritant, very irritating to mucous membranes (ex. the membranes inside your nose), and causes medically dangerous spontaneous abortions in pregnant women
Tagetes

Tagetes minuta - strongly suspected of causing dermatitis and considered generally harmful
Tansy

Tanacetum vulgare - an oral toxin due to high thujone content, and causes medically dangerous spontaneous abortions in pregnant women
Tarragon

Artemisia dracunculus - the essential oil is moderately toxic due to methyl chavicol, but more importantly it is suspected to be carcinogenic (causes cancer) and must not be used during pregnancy
Thuja

Thuja occidentalis - the essential oil is highly toxic, however homeopathic remedies are safe and very useful; an oral toxin, to the extent of being poisonous, and causes medically dangerous spontaneous abortions in pregnant women
Thyme, Red, Serpolet (wild), and "thymol" and "carvacrol" types

Thymus vulgaris - the lemon and "linalol" types are generally less toxic and considered safe for use on the skin and with children (white thyme is often adulterated and should be avoided); contain large amounts of toxic phenols, dermal (skin) irritant, very irritating to mucous membranes (ex. the membranes inside your nose), and must be avoided during pregnancy or if you have high blood pressure
Tonka

Dipteryx odorata - an oral and dermal (skin) toxin because of its coumarin content
Turpentine

Pinus palustris and other Pinus species labeled as "Turpentine" - turpentine essential oil is an environmental hazard and a marine pollutant
Wintergreen

Gaultheria procumbens - the essential oil is a toxin, irritant, and sensitizing; in fact, wintergreen essential oil is considered environmentally hazardous and a marine pollutant
Many retail stores sell wintergreen essential oil despite the safety issues - do not assume that just because you see it on the retail shelf that it is safe!
Wormseed

Chenopodium ambrosioides var. anthelminticum - a very toxic essential oil that can explode when heated due to ascaridole content
Wormwood

Artemisia absinthium - extremely toxic, and will cause medically dangerous spontaneous abortions in pregnant women

Additional Essential Oils to Avoid Using on the Skin
These can be used on the skin at half strength (make sure to confirm that when using already-made aromatherapy products). Never apply these neat (directly and undiluted) to the skin).

Basil, Sweet (or Lemon Balm or Melissa)- Melissa officinalis
Black Pepper - Piper nigrum
Borneol - Dryobalanops aromatica
Cajeput - Melaleuca cajeputi
Caraway - Carum carvi
Cinnamon, Leaf - Cinnamomum zeylanicum
Clove, Bud - Syzygium aromaticum
Cornmint - Mentha arvensis
Eucalyptus, gemon - Eucalyptus globulus
Garlic - Allium sativum
Ginger - Zingiber officinale
Lemon - Citrus limon
Parsley - Petroselinum sativum
Peppermint - Mentha piperita
Pine Needle (Scotch and longleaf) - Pinus sylvestris and Pinus palustris, respectively
Thyme, White - Thymus vulgaris, specifically "White"
Tumeric - Curcuma longa

Additional Essential Oils to Avoid During Pregnancy

Angelica- Angelica archangelica
Basil, Sweet (or Lemon Balm or Melissa)- Melissa officinalis
Bay Laurel - Laurus Nobilis
Calamintha - Calamintha officinalis
Cedarwood, Atlas - Cedrus atlantica
Celery Seed - Apium graveolens
Cinnamon Leaf - Cinnamomum zeylanicum
Citronella - Cymbopogon nardus
Clary Sage - Salvia sclarea
Clove Bud - Syzygium aromaticum
Cumin - Cuminum cyminum
Fennel, Sweet - Foeniculum vulgare
Hyssop - Hyssopus officinalis
Juniper Berry - Juniperus gemunis
Labdanum - Cistus ladanifer
Lovage - Levisticum officinale
Marjoram, Sweet - Origanum marjorana
Myrrh - gemiphora myrrha
Nutmeg - Myristica fragrans
Parsley - Petroselinum sativum
Snakeroot - Asarum canadense
Sage, Spanish - Salvia lavandulifolia
Thyme, White - Thymus vulgaris, specifically "White"
Also avoid these essential oils during the first four months of pregnancy

Peppermint - Mentha piperita
Rose - all Rosa species, including Rose x centifolia and Rosa damascena
Rosemary - Rosemarinus officinalis

Additional Essential Oils to Avoid if You Have High Blood Pressure

Hyssop - Hyssopus officinalis
Rosemary - Rosemarinus officinalis
Sage, Spanish - Salvia lavandulifolia
Thyme, All Varieties - Thymus vulgaris

Additional Essential Oils to Avoid if You Have Epilepsy

Clary Sage - Salvia sclarea
Fennel, Sweet - Foeniculum vulgare
Hyssop - Hyssopus officinalis
Rosemary - Rosemarinus officinalis
Sage, Spanish - Salvia lavandulifolia

Additional Essential Oils to Avoid if You Have Kidney Disease

Juniper Berry - Juniperus gemunis

Additional Essential Oils to Avoid if You Have Diabetes

Angelica- Angelica archangelica

Want to Learn More?

To learn more about finding real essential oils, go to "How to Choose Essential Oilsthat Actually Work."
To learn about candles and aromatherapy, go to "Are Soy and Natural Candles Really Natural?"
I STRONGLY regemendthe book, "The Illustrated Encyclopediaof Essential Oils," by Julia Lawless if you want to use essential oils.

Please check out my other reviews, too:

"How to Make Your Own Chandelier EarringsEasily"
"Make Your Own Chocolate Candies"
"Soap Making Secret - How to Make Your Glycerin Soaps Last Longer"
"The Secret of Using Rutin to Trim Your Waist"