Aromatherapy Part 2: The Dark Side

Although essential oils are natural products, it is still necessary to follow certain precautions when using them. Essential oils are very concentrated and volatile, this is why they work so well! There are certain essential oils that should never be used in aromatherapy. They are all either narcotic, toxic, capable of causing miscarriage, likely to provoke epileptic seizures or can seriously damage the skin.

Dangerous Essential Oils

These oils should Never be used

  • Aniseed Pimpinella anisum
  • Arnica Arnica montana
  • Boldo Leaf Peumus boldus
  • Calamus  Acorus calamus
  • Camphor Cinnamomum camphora
  • Cassia Cinnamomum cassie
  • Cinnamon Bark Cinnamomum zeylanicum
  • Costus Saussurea lappa
  • Bitter Almond Prunus amygdalis
  • Bitter Fennel Foeniculum vulgare
  • Elecampane Inula helenium
  • Horseradish Cochlearia armorica
  • Jaborandi Leaf Pilocarpus jaborandi
  • Mugwort Artemisia vulgaris
  • Mustard Brassica nigra
  • Origanum Origanum vulgare
  • Origanum (spanish) Thymus capitatus
  • Pennyroyal (European) Mentha pulegium
  • Pennyroyal (North American) Hedeoma pulegioides
  • Pine (dwarf) Pinus pumilio
  • Rue Ruta graveolens
  • Sage Salvia officinalis
  • Sassafras Sassafras albidum
  • Sassafras (brazilian) Ocotea cymbarum
  • Savin Juniperus sabina
  • Savory (summer) Satureia hortensis
  • Savory (Winter) Satureia montana
  • Southernwood Artemisia abrotanum
  • Tansy Tanacetum vulgare
  • Thuja (cedarleaf) Thuja occidentalis
  • Thuja Plicata Thuja plicata
  • Wintergreen Gaultheria procumbens
  • Wormseed Chenopodium anthelminticum
  • Wormwood Artemisia absinthium

Rosemary: Should not be used by people with epilepsy

In addition to the above list, there are a number of oils that do have valuable therapueutic properties, but need to be used with caution.

Oils that should not be used by people with Epilepsy

  • Fennel (Sweet) Foeniculum vulgare
  • Hyssop Hyssopus officinalis
  • Rosemary Rosmarinus officinalis

(plus Sage and Wormwood, from the previous list)

Geranium Oil: Do not use during Pregnancy

Oils That Should Not be Used During Pregnancy

  • Basil Ocimum basilicum
  • Birch Betula alba, B. lenta, B.alleghaniensis
  • Cedarwood Cedrus atlantica
  • Clary Sage Salvia sclarea
  • Cypress Cupressus sempervirens
  • Geranium Pelargonium asperum
  • Hyssop Hyssopus officinalis
  • Jasmine Jasminium officinale
  • Juniper Juniperis communis
  • Marjoram Origanum majorana
  • Myrrh Commiphora myrrha
  • Nutmeg Myristica fragrans
  • Peppermint Mentha piperata
  • Rosemary Rosmarinus officinalis
  • Tarragon Artemisia dranunculus
  • Thyme Thymus vulgaris
  • Camomile Anthemis nobilis, et al.
  • Lavender Lavandula vera
  • Rose Rosa centifolia, R.damascena  

Lemon Oil: Do not use for prolonged periods

Essential Oils with a Risk of Chronic Toxicity

Do not use these oils for more than a few days at a time

  • Basil Ocimum basilicum
  • Cedarwood Cedrus atlantica
  • Cinnamon Leaf Cinnamomum zeylanicum
  • Eucalyptus Eucalyptus globulus
  • Fennel (Sweet) Foeniculum vulgare
  • Hyssop Hyssopus officinalis
  • Lemon Citrus limonum
  • Orange Citrus aurantium
  • Nutmeg Myristica fragrans
  • Thyme Thymus vulgaris

Clove Oil: Can irritate the skin

Skin Irritants

Always dilute these oils to 1% before using

  • Angelica Angelica archangelica
  • Black Pepper Piper nigrum
  • Cinnamon Leaf Cinnamomum zeylanicum
  • Citronella Cymbopogon narus
  • Clove (all parts) Eugenia caryphyllus
  • Ginger Zingiber officinalis
  • Lemon Citrus limonum
  • Lemongrass Cymbopogon citratus
  • Lemon Verbena Lippia citriodora
  • Orange Citrus aurantium
  • Nutmeg Myristica fragrans
  • Peppermint Mentha piperata

Bergamot Oil: Can cause sunburn or sun damage

PhotoSensitising Oils

Do not use on skin before sun exposure

  • Angelica Angelica archangelica
  • Bergamot Citrus bergamia
  • Lemon Citrus limonum
  • Orange Citrus aurantium

I certainly don’t mean to scare anyone away from using essential oils, but I think a lot of us (myself included) think we can just go around using essential oils without a care in the world, without realising that they are incredibly strong and can have harmful effects if used improperly. It’s easy to think of the as just fancy scented oils, that you can add to whatever you want. For example, if you add lemon or orange oil to your body lotion recipe and use it every day, you run a risk of toxic levels building up in the body over time. Also be careful about gift giving. I was going to make peppermint shower scrub as a Christmas gift last year, until I researched peppermint oil and found it can cause spontaneous abortion!

Honestly if you are nervous, I would contact a Certified Aromatherapist (which is where I got these lists). I have been using essential oils myself for many years, with no ill effects, but I always research an oil before I use it.

Related Posts:

Aromatherapy Part 1: How it Works

Essential Oil of Bergamot

Essential Oil of Geranium

Essential Oil of Thyme

Cinnamon Bark: A Dangerous Essential Oil


  1. June 4, 2012 at 9:47 AM

    Why are they dangerous? Do the same restrictions apply to the dried herbs? Fresh herbs picked from the garden?

    • June 5, 2012 at 6:03 AM

      Essential oil are highly concentrated. The same precautions wouldn’t apply to fresh or dried herbs. Though you should always thoroughly read up on any herb (in any form) before using it as some are certainly poisonous. Some you can use parts of the plants but not others. An example is rhubarb ~ the stalks are fine, but the leaves are toxic.

      • Rhonda said,

        December 9, 2012 at 9:42 PM

        No simple answer – but a few pointers:
        – firstly ensure the oils are essential oils and not fragrant oils,
        – purchase oils from a reputable and knowledgeable source.
        – as with any medicinal product or drug, remember that using more is not better. essential oils are extracted from plants and contain naturally occurring chemical compounds. “natural” doesn’t automatically mean “safe”. the list goes on.
        perhaps i will start an aromatherapy blog, ive been involved in aromatherapy for 18 years and it still endlessly fascinates me.

  2. ybertaud9 said,

    June 9, 2012 at 6:22 AM

    Good to know… Made this into a photo post on my FB page, both I & II ! Thanks again! 😉

  3. Sherry wilborn galloway said,

    June 9, 2012 at 6:28 PM

    So much good information….thank you. I lover your pages. Lots of good stuff.

  4. drjeff7 said,

    June 11, 2012 at 9:16 PM

    I never knew that there was this much information about essential oils. Thanks.

  5. drjeff7 said,

    June 17, 2012 at 9:39 PM

    Please note that My blog has been moved to Thanks

  6. June 21, 2012 at 5:22 PM

    All well in your world chica? I haven’t been on here much and see you haven’t either…hope you are good. 🙂

  7. Kimberly said,

    June 25, 2012 at 7:15 PM

    Wow! Great info!

  8. Kory said,

    June 26, 2012 at 1:41 PM

    I’m wondering what your sources are? I’ve been taught differently on quite a few of these…

    I do agree that oils should be researched, but I would read books on it rather than doing internet searches, because the horror stories are always what will come up that way.

    One that I see people using all the time that makes me nervous is oregano. It’s an extremely strong EO that should be used carefully, but I see people dropping it on their tongue like it’s no big deal. Kids end up in the hospital that way.

    • June 27, 2012 at 8:28 AM

      Kory, I used Aromatherapy an A-Z by Patricia Davis, Prescription for Nutritional Healing by Phyllis Balch. The Complete Medicinal Herbal by Penelope Ody.

  9. Kory said,

    June 26, 2012 at 6:26 PM

    Just wanted to add… Good books are: aromatherapy for the healthy child and The complete book of essential oils and aromatherapy by Valerie Worwood. There’s also good info here:

  10. Terra said,

    October 10, 2012 at 8:07 PM

    I have a question about oils. I see that you use Young Living oils. Are they pure essential oils with no fillers or additives? DoTerra oils are taking off up here and they say you can put lots of their oils directly on your skin undiluted (i.e. lavender, citrus..) because they are the purest oils on the market so they are safe to ingest and apply topically. What is your experience with this?

  11. October 24, 2012 at 5:12 PM

    Hey, Where have you been? I miss your great blogging posts! Are you retired from blogging? Maybe not such a bad idea 🙂

  12. November 4, 2012 at 1:35 AM

    There’s quite a few that I can’t fathom why they are on this danger list…

    My favorite for example. Sage, was studied to be beneficial for Alzheimer

  13. Rena said,

    November 17, 2012 at 11:49 AM

    Are there any essential oils you would recommend that would be safe and good for you?

  14. Nik said,

    December 5, 2012 at 9:20 AM

    I’m new to essential oils, but when you are saying they shouldn’t be used, or used with caution, are you referring to being applied to the skin/inhaled or both? 🙂 Love your site, I’m getting lots of useful information here on the topic!!

  15. Kathy Davison said,

    January 3, 2013 at 10:03 AM

    Just discovered this blog. I’m very interested in Bergamot oil uses in foods as I need to avoid them. Bergamot oil in Earl Grey tea and cosmetics cause a severe neuromuscular reaction in me. Do you have a source listing what foods/beverages contain it. I’ve searched but food flavorings do not have to be listed as ingredients. Any help would be so greatly appreciated.

  16. Mariepierre said,

    January 7, 2013 at 5:38 PM

    Yes natural remedies AND essential oils should not be used without professionnal supervision or deeper knowledge. The same goes for a lot of stuff out there (natural or not!) Maybe your warning should have been “There are certain essential oils that should never be used in aromatherapy WITHOUT A PROFESSIONNAL ADVISE”… There are some essential oils on your black list that are awsome. Yes they should be used very carefully in some cases but not simply put aside…
    But this is only my opinion 😉

    • Svea Bryan said,

      September 22, 2013 at 9:08 PM

      I agree. We need to consider clinical studies that show the medicinal purposes and at the same time be aware of claims that essential oils do everything except harm. There are many studies that show proper doses, applications and expected outcomes. The clinical research also include lethal doses in lab animal. I think the list of dangerous oils is extensive and makes me question the validity of that claim as much as I question the claims that essential oils are the cure all for any and everything. Let’s not throw the baby out with the bath water.

  17. K Albro said,

    April 2, 2013 at 9:42 AM

    Why is cinnamon bark so dangerous? I use it in my homemade toothpaste. What about natural cinnamon candies? I feel horrible now that I let my son taste my Eden’s Garden 100% pure EO. He loves to put a drop on his tongue. Yikes!!! I figured it was OK since it is an ingredient in many natural toothpaste recipes. Also, lemon EO? It comes from lemons. Why would it be so dangerous? I add about 8 drops to my natural deodorant recipe (coconut oil, baking soda, corn starch). It makes this light fluffy lemon crème that is just divine. I guess I have a lot to learn about EOs. Thanks for your post!

    • April 2, 2013 at 9:55 AM

      Kristy, Essential Oils are highly concentrated plant oils. I would recommend reading the information HERE from Mountain Rose Herbs I cannot recommend the ingestion of specific essential oils, or use for specific conditions. It is your responsibility to be aware of the precautions of ingesting any essential oil, and to seek the advice of a qualified health professional to determine if ingestion of essential oils is right for you.

    • Svea Bryan said,

      September 22, 2013 at 8:59 PM

      Q: why is Cinnamon bark dangerous? A: The oil can burn the skin. When applied to the skin it should be diluted with a carrier oil, such as almond oil. Natural candies aren’t likely made with essential oils. The essential oils are highly concentrated. As for lemon oil, the toxins that I think are being referred to come from pesticides used on the plants. It gets into the peel where the oils are stored. The oils of lemon, grapefruit, and orange are amazing and have many uses. They smell great. Only organically grow fruits would be free of toxic residue and safe for internal use. I NEVER recommend taking these internally. Only a clinical aroma therapist or practitioner with a license to prescribe should recommend this.

  18. May 15, 2013 at 7:16 AM

    […] Aromatherapy Part 2: The Dark Side […]

  19. Svea Bryan said,

    September 22, 2013 at 8:44 PM

    Regarding cold pressed essential oils, ( Found in citrus peels). It’s my understanding that if the fruit was grown organically then the peels shouldn’t have toxins that would end up n the essential oil. Any comments?

  20. May 2, 2014 at 12:47 AM

    […] Aromatherapy Part 2: The Dark Side […]

  21. April 25, 2015 at 11:50 PM

    […] Aromatherapy Part 2: The Dark Side […]

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