According to the NAHA - The National Association for Holistic Aromatherapy
from
http://www.naha.org/explore-aromatherapy/safety/
Factors that influence the safety of essential oils include
1. Quality of essential oil being utilized: Adulterated essential oils increase the likelihood of an adverse response and hence the need for pure, authentic, and genuine essential oils is of the utmost importance.
2. Chemical composition of the oil: Essential oils rich in aldehydes (e.g., citronellal, citral) and phenols (e.g., cinnamic aldehyde, eugenol) may cause skin reactions. Essential oils rich in these constituents should always be diluted prior to application to the skin. According to Schnaubelt, “diluting such oils so that the resulting solution becomes non-irritant, may require diluting them to concentrations much lower than in normal circumstances. Another option is to blend such irritant oils asymmetrically with other essential oils, which mitigate their irritant effects.”3
3. Method of application: Essential oils may be applied on the skin (dermal application), inhaled, diffused or taken internally. Each of these methods have safety issues which need to be considered. The potential safety concerns with dermal application will be discussed below. With regard to inhalation, inhalation, from a safety standpoint, presents a very low level of risk to most people. Even in a relatively small closed room, and assuming 100% evaporation, the concentration of any essential oil (or component thereof) is unlikely to reach a dangerous level, either from aromatherapy massage, or from essential oil vaporization.4
Tisserand and Balacs further point out that “the only likely risk would be from prolonged exposure (perhaps 1 hour or more) to relatively high levels of essential oil vapor which could lead to headaches, vertigo, nausea and lethargy”. With regard to internal use, the safety concerns of this method of application will be explored in more depth by the National Association for Holistic Aromatherapy over the next two years.
4. Dosage/dilution to be applied: Most aromatherapy oil based blends will be between 1 and 5 percent dilutions, which typically does not represent a safety concern. As one increases dilution, potential dermal (skin) reactions may take place depending on the individual essential oil, the area in which the oil is applied, and other factors related to the client’s own sensitivity levels. Any excessive usage of essential oils may cause irritation or other undesired effects due to their lipophilic nature.5
5. Integrity of skin: Damaged, diseased, or inflamed skin is often more permeable to essential oils and may be more sensitive to dermal reactions. It is potentially dangerous to put undiluted essential oils on to damaged, diseased or inflamed skin. Under these circumstances the skin condition may be worsened, and larger amounts of oil than normal will be absorbed. Sensitization reactions are also more likely to occur.6
6. Age of client: Infants, toddlers, and young children are more sensitive to the potency of essential oils and safe dilutions include .5 - 2.5% depending on condition. Also, some essential oils should simply be avoided for this population, e.g. Birch or Wintergreen, which are both rich in methyl salicylate and Peppermint. Elderly clients may have more skin sensitivities so a reduced concentration/dilution may be indicated.
Possible Dermal Reactions
Of primary importance to the aromatherapists is the safety of essential oil application to the skin. Dermal or skin reactions that may occur with essential oils include: irritation, sensitization and phototoxicity/photosensitization.
A dermal irritant will produce an immediate effect of irritation on the skin. The reaction will be represented on the skin as blotchy or redness, which may be painful to some individuals. The severity of the reaction will depend on the concentration (dilution) applied.
General safety guidelines include: avoid application of known dermal irritant essential oils on any inflammatory or allergic skin condition; avoid undiluted application; avoid application on open or damaged skin; and dilute known dermal irritants with appropriate vegetable oil or other carrier. If you suspect a client has sensitive skin, perform a skin patch test. Table 1 lists some common essential oils considered to be dermal irritants.
Dermal Irritants (Table 1)
| Essential Oil | Latin Name |
| Bay | Pimento racemosa |
| Cinnamon bark or leaf | Cinnamomum zeylanicum* |
| Clove bud | Syzygium aromaticum |
| Citronella | Cymbopogon nardus |
| Cumin | Cuminum cyminum |
| Lemongrass | Cymbopogon citratus |
| Lemon verbena | Lippia citriodora |
| Oregano | Origanum vulgare |
| Tagetes | Tagetes minuta |
| Thyme ct. thymol | Thymus vulgaris |
*bark is more irritating than leaf
Dermal sensitization
Dermal sensitization is a type of allergic reaction. It occurs on first exposure to a substance, but on this occasion, the noticeable effect on the skin will be slight or absent. However, subsequent exposure to the same material, or to a similar one with which there is cross-sensitization, produces a severe inflammatory reaction brought about by cells of the immune system (T-lymphocytes).7 The reaction will be represented on the skin as blotchy or redness, which may be painful to some individuals.
The problem with dermal sensitization is that once it occurs with a specific essential oil the individual is most likely going to be sensitive to it for many years and perhaps for the remainder of his/her life. The best way to prevent sensitization is to avoid known dermal sensitizers and avoid applying the same essential oils every day for lengthy periods of time. Sensitization is, to an extent, unpredictable, as some individuals will be sensitive to a potential allergen and some will not.8
According to Burfield (2004), the following oils listed in Table 2 are considered to be dermal sensitizers and are not recommended for use in aromatherapy massage.
Dermal Sensitizers (Table 2)
| Essential Oil | Latin Name |
| Cassia | Cinnamomum cassia |
| Cinnamon bark | Cinnamomum zeylanicum |
| Peru balsam | Myroxylon pereirae |
| Verbena absolute | Lippia citriodora |
| Tea absolute | Camellia sinensis |
| Turpentine oil | Pinus spp. |
| Backhousia | Backhousia citriodora |
| Inula | Inula graveolens |
| Oxidized oils from Pinaceae family (e.g., Pinus and Cupressus species) and Rutaceae family (e.g., citrus oils) |
Photosensitization
An essential oil that exhibits this quality will cause burning or skin pigmentation changes, such as tanning, on exposure to sun or similar light (ultraviolet rays). Reactions can range from a mild color change through to deep weeping burns. Do not use or recommend the use of photosensitizing essential oils prior to going into a sun tanning booth or the sun. Recommend that the client stay out of the sun or sun tanning booth for at least twenty-four hours after treatment if photosensitizing essential oils were applied to the skin. Certain drugs, such as tetracycline, increase the photosensitivity of the skin, thus increasing the harmful effects of photosensitizing essential oils under the necessary conditions. Table 3 lists some common essential oils considered to be photosensitizers.
Photosensitizers (Table 3)
| Essential Oil | Latin Name |
| Angelica root | Angelica archangelica |
| Bergamot | Citrus bergamia |
| Cumin | Cuminum cyminum |
| Distilled or expressed grapefruit (low risk) | Citrus paradisi |
| Expressed lemon | Citrus limon |
| Expressed lime | Citrus medica |
| Orange, bitter (expressed) | Citrus aurantium |
| Rue | Ruta graveolens |
Non-phototoxic citrus oils (Table 4)
| Essential Oil | Latin Name |
Bergamot: Bergapteneless
(FCF: Furanocoumarin Free) | Citrus bergamia |
| Distilled lemon | Citrus limon |
| Distilled lime | Citrus medica |
| Mandarin - Tangerine | Citrus reticulata |
| Sweet orange | Citrus sinensis |
| Expressed tangerine | Citrus reticulata |
| Yuzu oil (expressed or distilled) | Citrus juno |
Idiosyncratic irritation or sensitization
Idiosyncratic irritation or sensitization is an uncharacteristic or unusual reaction to a commonly used essential oil. This type of reaction is difficult to predict and rarely occurs but is a possibility.
Mucous membrane irritant
A mucous membrane irritant will produce a heating or drying effect on the mucous membranes of the mouth, eyes, nose, and reproductive organs. It is recommended that mucus membrane irritating essential oils not be used in a full body bath unless placed in a dispersant first (e.g., milk, vegetable oil). It would also be wise to put the dispersed essential oils into the water after you have gotten into the bath. Bay, clove, cinnamon bark, lemongrass, and thyme ct. thymol essential oils should be avoided in baths completely. Table 5 lists some common essential oils considered to be mucous membrane irritants.
Mucous membrane irritants (Table 5)
| Essential Oil | Latin Name |
| Bay | Pimento racemosa |
| Caraway | Carum carvi |
| Cinnamon bark or leaf | Cinnamomum zeylanicum |
| Clove bud or leaf | Syzygium aromaticum |
| Lemongrass | Cymbopogon citratus |
| Peppermint | Mentha x piperita |
| Thyme ct. thymol | Thymus vulgaris |
Other Safety Considerations
NAHA will be adopting similar guidelines as the International Federation of Professional Aromatherapists. Here are their guidelines. For more information about IFPA, please see here.
The use of essential oils during pregnancy is a controversial topic and one that is yet to be fully understood. The main concern during pregnancy appears to be the risk of 
essential oil constituents crossing over into the placenta. According to Tisserand and Balacs, crossing the placenta does not necessarily mean that there is a risk of toxicity to the fetus; this will depend on the toxicity and the plasma concentration of the compound.9 It is probable that essential oil metabolites cross the placenta due to the intimate (but not direct) contact between maternal and embryonic or fetal blood. Tony Burfield goes on to say, “to my thinking the responsible attitude is to discourage the use of essential oils completely during the first few months of pregnancy”.10
Jane Buckle comments “the use of essential oils in pregnancy is a contentious subject, especially during the vital first 3-month period. It is extremely unlikely that a nightly bath containing a few drops of essential oils will cause any problems for the unborn child” and later states “there are no records of abnormal fetuses or aborted fetuses due to the ‘normal’ use of essential oils, either by inhalation or topical application.”11
According to Wildwood, “A common myth in aromatherapy is that massage oils containing essential oils such as Clary sage, rose or even rosemary can cause a miscarriage and hence should be avoided throughout pregnancy. Authors such as Ron Guba, Kurt Schnaubelt, and Chrissie Wildwood have all pointed out that there have been ‘no recorded cases of miscarriage or birth defect resulting from aromatherapy massage using therapeutic applications of any essential oil.”12
Ron Guba points out that toxicity during pregnancy is almost exclusively due to pregnant women taking large, toxic doses of essential oils, notably pennyroyal (rich in the ketone, pulegone, which is metabolized to the highly toxic furan epoxide, menthofuron) and parsley seed (rich in the dimethyl ether, apiol) in an attempt to abort the fetus.13 And Battaglia shares this insight: “the judicious use of essential oils together with appropriate forms of massage by a skilled therapist can help ease the discomforts of pregnancy and provide a sense of nurturing that will comfort the mother at times she is likely to be feeling rather fragile.”14
Due to the lack of clear information regarding the toxicity of essential oils during pregnancy, it would be best to adhere to general safety guidelines. According to Tisserand and Balacs, the following essential oils should not be used during pregnancy: wormwood, rue, oak moss, Lavandula stoechas, camphor, parsley seed, sage, and hyssop.15
Essential oils that appear to be safe include cardamon, German and Roman chamomile, frankincense, geranium, ginger, neroli, patchouli, petitgrain, rosewood, rose, sandalwood, and other nontoxic essential oils.16 It would also be prudent to avoid the internal or undiluted application of essential oils throughout pregnancy.
Essential oils to Avoid throughout Pregnancy, Labor, and while Breastfeeding (Table 6)
| Essential Oil | Latin Name |
| Aniseed | Pimpinella anisum |
| Basil ct. estragole | Ocimum basilicum |
| Birch | Betula lenta |
| Camphor | Cinnamomum camphora |
| Hyssop | Hyssopus officinalis |
| Mugwort | Artemisia vulgaris |
| Parsley seed or leaf | Petroselinum sativum |
| Pennyroyal | Mentha pulegium |
| Sage | Salvia officinalis |
| Tansy | Tanacetum vulgare |
| Tarragon | Artemisia dracunculus |
| Thuja | Thuja occidentalis |
| Wintergreen | Gaultheria procumbens |
| Wormwood | Artemisia absinthium |
There has been much social media discussion recently (February 2012) about the wisdom or otherwise of putting essential oils into your eyes to treat eye problems. This arose from two webpages,
here and (2nd page no longer available). One of these, on the Livestrong website, states: “
More and more people are choosing to use alternative medicines to treat minor illnesses rather than taking a prescription. Putting essential oils in or near the eyes isn’t something that is widely known about, but there are several that can aid in the treatment of eye problems. Before using essential oils for your eyes, always contact your doctor.
Clary sage is the essential oil that is most widely used to treat vision problems. It is placed in the eye, so advice from an optometrist is important before use. Clary sage is used as a cleanser for the eyes. It can also be used to clear eye sight due to foggy vision or an injury to the eyes. Clary sage can also be used to brighten the eyes and improve vision. Finally, it can have beneficial results for people with eye issues related to aging.” -Eliza Martinez
EYE IMAGE: Damage to the cornea after inadvertent adminstration of Olbas Oil. Courtesy of Nature Publishing Group
This actually dates from May 2010, but judging from the related comments, has only recently been noticed. The statement that “Clary sage is the essential oil that is most widely used to treat vision problems” is not true, since there are no essential oils commonly used to treat vision problems. The only evidence for any essential oil treating any eye problem relates to tea tree oil and eyelash mites (see below). The reference to clary sage probably derives from 17th century European herbalists, but this refers to using clary sage seeds, or mucilage made from them, and not to clary sage essential oil: “The seed put into the eyes clears them from motes and such like things gotten within the lids to offend them, and it also clears them from any white and red spots which may be on them” (Culpeper 1652). Another common name for clary sage (Salvia sclarea) was “clear eye” because of this common use of the seeds, which probably pre-dated Culpeper by many years. “Clary” may derive from “clear-eye.”
Not only is there no evidence that any essential oil can help with vision problems, age-related or otherwise, but placing any essential oil “in the eye” is extremely dangerous advice. Almost any undiluted essential oil coming into contact with the ocular membranes will be corrosive, possibly causing scarring of the cornea, and certainly causing significant pain.
Eye damage I could find no reports in the literature of ocular accidents involving single essential oils, but there are several for Olbas oil. This is a mixture of essential oils and menthol:
35.45% Eucalyptus oil
35.45% Dementholized mint oil
18.5% Cajuput oil
4.1% Menthol
3.7% Wintergreen oil
2.7% Juniper berry oil
0.1% Clove oil
A 2009 report from an ophthalmologist in Bristol UK, describes partial loss of corneal tissue (ie erosion) when a 73-year-old man dripped Olbas Oil into his left eye (he had no right eye) because he thought he was using eye drops (see picture above). He was “considerably incapacitated”, but recovered after a week of treatment with “topical antibiotics and lubricants”. On checking, the author found that just his hospital, in the previous 18 months, had seen 12 patients who had mistakenly dripped Olbas Oil into one eye. He describes the result as a chemical burn, though he found that Olbas Oil in tears was pH neutral (most chemical burns are caused by substances that are strongly acid or alkaline). All “Olbas Oil patients” recovered fully within one week following intensive treatment (Adams et al 2009).
Olbas Oil may cause problems even when not applied directly to the eyes. The mother of a 4-month-old boy placed several drops of Olbas Oil in his right nostril in an attempt to help his respiratory infection, not realizing that the product warns against use in infants. The child immediately showed signs of respiratory distress, and was taken to the emergency room. Two hours after admission his eyes became inflamed, and examination revealed bilateral superficial corneal scarring. He also had conjunctivitis, and could not open his eyes. They were flushed with saline over four days, and he recovered with no residual scarring (Wyllie and Alexander 1994).
Emergency treatment
More than 65,000 work-related eye injuries and illnesses are reported annually in the USA, a “significant percentage” of these being ocular chemical burns. They require rapid treatment, and severe burns have a poor prognosis. The standard treatment is copious irrigation with saline solution for 1-2 hours. Contact lenses should not be removed initially (Peate 2007). With essential oils, fatty oil has been suggested as an appropriate first aid treatment though the advantage of saline is that the eyes can be continually flushed, and this is less easy with fatty oil.
What about diluted essential oils?
The second article describes using essential oils diluted to (by my estimation) about 3%. It includes the following advice:
“Here is a truly natural solution, which has been shown to benefit your eye health and the only one I will use. Gary Young has used this recipe for his patients at the Ecuador Clinic for macular degeneration, health issues, cataracts, and improving sight. I’ve been using it for a couple of years and love it! I started using this recipe before I had to have a vision exam in order to purchase new contacts. And I knew my vision had deteriorated from my last exam. So I put the drops in my eyes every night for about 6 months prior to the exam and my prescription had not changed according to their records, but I know what I was not seeing and I know what I was seeing as a result of using these drops – clearly my vision had improved! The recipe is as follows:
7-10 drops of Frankincense
7-10 drops of Rosemary
7-10 drops of Cypress
2 Tbsp of V-6
Put oils in a glass dropper bottle with a lid on it. My experience has been that I can see much more clearly just after putting the drops in my eye so I am also going to experiment with putting a drop in my eyes in the morning” (
Diana Ewald).
“V-6” is a proprietary blend of vegetable oils. The above implies that using these oils on a daily basis is likely to have a healing effect in cases of cataract, macular degeneration or failing eyesight. Although the article continues to describe various effects of the essential oils, none of them have any relationship with any of these conditions. So the question arises – how to weigh potential benefits against potential risks?
The word “experiment” in the above seems appropriate. Eyesight problems are difficult to treat, and once damage has occurred, recovery is not always simple. A 3% dilution may not be sufficient to cause corneal erosion, but on the other hand there is no evidence of any benefit. One concern is that the wrong dilution may be used, and the risk of this is substantial. For example, it would be easy to confuse “tbsp” with tsp”, resulting in a dilution of about 10% instead of 3%.
In a Chinese study, an ointment containing 5% tea tree oil was used by patients whose eyelash follicles were infested with “eyelash mites” (Demodex folliculorum). The ointment was applied to the lid margins with eyes closed, daily for 4 weeks after washing the face, and resulted in considerably less itching and fewer mites. Two of the 24 patients experienced slight irritation from the ointment. The 5% concentration was arrived at after preliminary testing using various dilutions on rabbit eyes (Gao et al 2012).
Conclusions
* Undiluted essential oils should not be applied to the eyes.
* It is rash to suggest that essential oils are commonly used to treat eye problems
* Eye injuries and diseases are medical conditions, and any product claiming to treat them is a medicine, subject to drug legislation.
* There is currently no evidence that applying dilutions of essential oil to the eyes will be beneficial in any condition.
* Diluted (5%) tea tree oil may help eradicate eyelash mites, but it should not be placed into the eyes.
References
(for "The Eyes" only)
Adams MK, Sparrow JM, Jim S et al 2009 Inadvertent administration of Olbas oil into the eye: a surprisingly frequent presentation. Eye (London) 23:244
Culpeper N 1652 The English Physitian, or an Astro-physical discourse of the vulgar herbs of this nation. Being a compleat method of physick, whereby a man may preserve his body in health; or cure himself, being sick. Thomas Kelly, London
Gao YY, Xu DL, Huang IJ et al 2012 Treatment of ocular itching associated with ocular demodicosis by 5% tea tree oil ointment. Cornea 31:14-17
Peate WF 2007 Work-related eye injuries and illnesses. American Family Physician 75:1017-1022
Wyllie JP, Alexander FW 1994 Nasal instillation of ‘Olbas Oil’ in an infant. Archives of Disease in Childhood 70:357-358
This article also appears in the International Journal of Professional Holistic Aromatherapy, Vol. 1 Issue 4
General Safety
1. Keep all essential oils out of reach of children and pets.
2. Do not use or recommend the use of photosensitizing essential oils prior to going into a sun tanning booth or the sun. Recommend that the client stay out of the sun or sun tanning booth for at least twenty-four hours after treatment if photosensitizing essential oils were applied to the skin.
3. Avoid prolonged use of the same essential oils.
4. Avoid the use of essential oils you know nothing about on your clients. Research and get to know the oil prior to using it on others.
5. Avoid the use of undiluted essential oils on the skin, unless otherwise indicated.
6. If you suspect your client may be sensitive to specific essential oils or if your client has known allergies or sensitivities, it may be wise to perform a skin patch test.
7. Know the safety data on each essential oil and place into context of use and knowledge.
8. Use caution when treating a female client who suspects she is pregnant or has been trying to become pregnant.
9. Keep essential oils away from the eyes.
10. Essential oils are highly flammable substances and should be kept away from direct contact with flames, such as candles, fire, matches, cigarettes, and gas cookers.17
11. Make sure your treatment room has good ventilation.
12. Do not use essential oils internally unless properly trained in the safety issues of doing so. Please visit NAHA's approved schools to explore education in aromatherapy.
Safety Measures
1. If essential oil droplets accidentally get into the eye (or eyes) a cotton cloth or similar should be imbued with a fatty oil, such as olive or sesame, and carefully swiped over the closed lid.18 And / Or, Immediately flush the eyes with cool water.
2. If an essential oil causes dermal irritation, apply a small amount of vegetable oil or cream to the area affected and discontinue use of essential oil or product that has caused dermal irritation.
3. If a child appears to have drunk several spoonfuls of essential oil, contact the nearest poison control unit (often listed in the front of a telephone directory). Keep the bottle for identification and encourage the child to drink whole or 2% milk. Do not try to induce vomiting.19
Health Benefits of Oregano Essential Oil
Antibacterial: Just as it protects you against viral infections, oregano oil protects you