Potential Problems With Purity
One major concern raised about essential oils is their purity and the fidelity of their chemical composition. The specific aromatic chemicals in each essential oil are maintained for each species, but the proportions of each change even with the time of year.12 Gas chromatograph analysis of the same oil distilled with different techniques showed that the proportions of aromatic chemicals varied with technique. However, the major constituents of the oil remained present in large quantities, just at different percentages.1 Even using the same distillation technique for different time periods can greatly affect the yield and composition of the oil. Although the percentage of each aromatic compound can be affected by distillation times, the antioxidant and antimicrobial effects of the oil remain constant regardless of these variables.2 There is clearly a lack in standardization in essential oil production, which may not be an issue for its use in complementary medicine if its properties are maintained regardless.
Safety Concerns and Regulations
With essential oils being a natural cure for everyday ailments, some people are turning first to oils for every cut and bruise. The danger in these natural cures is that essential oils can cause several types of dermatitis and allergic reactions. The development of allergies to essential oils is at an even higher risk, considering people frequently put them on wounds and rashes where the skin barrier is already weakened. Many essential oils fall into the fragrance category in patch tests, negating the widely circulating blogger and online reports that essential oils cannot cause allergies.
Some of the oils, although regarded safe by the US Food and Drug Administration for consumption, can cause dermatitis from simple contact or with sun exposure.13 Members of the citrus family are notorious for the phytophotodermatitis reaction, which can leave hyperpigmented scarring after exposure of the oils to sunlight.14 Most companies that sell essential oils are aware of this reaction and include it in the warning labels.
The legal problem with selling and classifying essential oils is that the US Food and Drug Administration requires products intended for treatment to be labeled as drugs, which hinders their sales on the open market.13 It all boils down to intended use, so some companies sell the oils under a food or fragrance classification with vague instructions on how to use said oil for medicinal purposes, which leads to lack of supervision, anecdotal cures, and false health claims. One company claims in their safety guide for topical applications of their oils that “[i]f a rash occurs, this may be a sign of detoxification.”15 If essential oils had only minimal absorption topically, their safety would be less concerning, but this does not appear to be the case.
Absorption and Systemics
The effects of essential oils on the skin is one aspect of their use to be studied; another is the more systemic effects from absorption through the skin. Most essential oils used in small quantities for fragrance in over-the-counter lotions prove only to be an issue for allergens in sensitive patient groups. However, topical applications of essential oils in their pure concentrated form get absorbed into the skin faster than if used with a carrier oil, emulsion, or solvent.16 For most minor uses of essential oils, the body can detoxify absorbed chemicals the same way it does when a person eats the plants the oils came from (eg, basil essential oils leaching from the leaves into a tomato sauce). A possible danger of the oils’ systemic properties lies in the pregnant patient population who use essential oils thinking that natural is safe.
Many essential oils, such as lavender (L officinalis), exhibit hormonal mimicry with phytoestrogens and can produce emmenagogue (increasing menstrual flow) effects in women. Other oils, such as those of nutmeg (Myristica fragrans) and myrrh (Commiphora myrrha), can have abortifacient effects. These natural essential oils can lead to unintended health risks for mother and baby.17 With implications this serious, many essential oil companies put pregnancy warnings on most if not all of their products, but pregnant patients may not always note the risk.
Conclusion
Essential oils are not the newest medical fad. They outdate every drug on the market and were used by some of the first physicians in history. It is important to continue research into the antimicrobial effects of essential oils, as they may hold the secret to treatment options with the continued rise of multidrug-resistant organisms. The danger of these oils lies not in their hidden potential but in the belief that natural things are safe. A few animal studies have been performed, but little is known about the full effects of essential oils in humans. Patients need to be educated that these are not panaceas with freedom from side effects and that treatment options backed by the scientific method should be their first choice under the supervision of trained physicians. The Table outlines the uses and side effects of the essential oils discussed here.
