Most of the adverse effects seen with EOs involve routes other than inhalation. The common skin reactions, such as irritation, photosensitization and allergy, as well as oral overdosing, are largely avoided when using the inhalation route. Although it is not impossible, the likelihood of an inhalation-triggered allergic reaction with the controlled administration of any of the EOs mentioned in this course is extremely unlikely.
Without an established reporting mechanism or database of adverse reactions associated with essential oils, it is difficult to quantify the risk related to EO use. In 2012, researchers tried to find meaningful data from the published reports that existed. They used all worldwide available electronic databases, and found 42 reports of adverse events involving essential oil use. The most prevalent problems were skin related, with the majority classified as “mild to moderate”. Five complications were linked to some form of inhaled aromatherapy; 3 from nasal instillation in small children (a practice which is not recommended as detailed in the section Use in Children, below), one female adult who developed a facial skin rash after inhaling bergamot oil, and a 12 month old who developed seizures after 4 days of prolonged bathing in unknown quantities of eucalyptus, pine and thyme EOs (57).
TIEO use in Pregnancy
Many books and websites on essential oils display an abundance of caution regarding their use in pregnancy, often issuing advisories unrelated to evidence or correlation to available facts. This is somewhat understandable from the viewpoint of liability and recognition of the limits of available information. Studies examining the effects of medications or therapies in pregnant women pose an ethical dilemma, so it is common to routinely advise against a product’s use in pregnancy to avoid a potential risk to the woman or her fetus.
The focus of this course is specific to inhaled essential oil therapy, and many of these concerns are eliminated for most individuals, including women who are pregnant. TIEO is limited to inhalation of essential oil vapors and avoids any other contact of the oil itself. The only direct and significant adverse outcomes associated with EO use in pregnancy that are identified in the available literature, are those from copious oral ingestion of non-therapeutic EOs such as Pennyroyal, primarily used in attempts to induce abortion (58).
Over 60% of US women who are pregnant and suffering from nausea, employ some type CAM, with ingesting ginger being the most common intervention. (59). No data exists that implicate the essential oils recommended in this course with abnormal fetal development, and given their extensive history of use, none is expected (60). Canadian researchers examined herbal use and pregnancy outcomes such as miscarriage rate, birth weight, malformations, live vs. stillbirth and neonatal distress, and were unable to find any correlations. They concluded that restricting most herbal products, especially the ones that had a longstanding history of safe use, such as peppermint and ginger, was inappropriate (61).
To put it in perspective, nausea and vomiting can be a significant issue for women in the first trimester of pregnancy, causing dehydration and nutritional deficiencies that can result in lost days from work, family disruption, and significant emotional distress. In contrast, intermittently inhaling low concentrations of commonly used EOs appears safe in pregnancy, and can provide effective non- pharmacologic relief from a condition that can become debilitating. In addition, self-administered TIEO can provide a greater sense of self-efficacy and resilience for women with persistent nausea of pregnancy.
Asthma and Reactive Airway Disease
Essential oils have long played a role in helping ease respiratory ailments. Probably the most familiar examples are the eucalyptus, menthol and camphor found in Vicks Vaporub, or the peppermint and spearmint common in cold and cough medicines. For healthcare providers seeking answers about TIEO use in patients with asthma, Tisserand says it best: “…there is no evidence that essential oils cause either irritant or allergic asthma, but there is evidence suggestive of therapeutic effects” (25).
Asthma is one of the most common respiratory diseases, and afflicts approximately 17.7 million people in the US (62). Asthma is characterized by reversible airflow obstruction and bronchial hyper- responsiveness to various stimuli that can lead to wheezing, coughing and the inability to take adequate breaths. It is mostly triggered by an allergen, such as dust, pet dander or cigarette smoke. Reactive Airway Disease (RAD) is a term used almost interchangeably with asthma, but is defined by being caused by an irritant, such as smoke, gastric reflux and pungent odors from cleaning supplies or perfumes.
Irritants interact with specialized receptors lining the airways called TRP ion channels. When activated, these channels release neuropeptides, which in turn can cause inflammation, bronchial constriction and edema. People with asthma and RAD have an increased number and sensitivity of two subcategories of these receptors, TRVP and TRPA (63).
Peppermint’s main constituent, menthol, is a TRVP antagonist, with anti-allergy and anti-inflammatory properties (64). Studies have shown that when menthol vapor is inhaled, the urge to cough is diminished. Menthol accomplishes this by reducing the airway’s sensitivity to irritants, via interaction with both TRVP and TRPA, in addition to the tissue surrounding the receptors (65).
In a recent animal study investigating lavender’s effect on asthma, it was found that inhaling the vapor of lavender essential oil lowered airway resistance and resulted in fewer eosinophil cells, less mucous in the lungs, and lower cytokine levels, correlating to less immune system stress. The researchers concluded that inhaling the vapor of lavender inhibits allergic inflammation and may be a useful asthma treatment in humans (66).
Use In Children
The essential oils listed in this course can, and are, being safely used with children in the clinical setting (67).
Some aromatherapy sources issue strict warnings about peppermint EO use with children. This recommendation appears to stem from inappropriate or accidental administration of pungent mixtures containing menthol (either the solid constituent of oil of mint or a synthetic product) and camphor. These mixtures were instilled inside or near the nostrils, eliciting reactions such as dyspnea, loss of consciousness, agitation, and metabolic acidosis. In one report the ages of the affected children were 1 month, 9 months and 3 years. Fortunately, all children made a full recovery (68).
Over the counter preparations containing menthol are found in drug stores throughout the world, and are used in children as young as 3 months old. These products can be safely used when appropriate precautions are followed. Peppermint EO, or any strong aromatic vapor, must be administered indirectly and in a low enough ambient concentration to prevent a nasal reaction to its pungency, such as tissue swelling or secretion production. Infants have very small, easily collapsible nasal passages that can quickly become too diminished for adequate airflow, thus leading to respiratory distress. Successful TIEO outcomes are achieved in children by introducing low concentrations of EO vapor carefully, and vigilantly monitoring each child for its effects.
Additional Safety Notes
- Precautions must be taken to prevent children from ingesting essential oils
- Undiluted essential oils should never be used on a child
- Skin preparations containing dilute essential oils should not be placed inside or under a child’s nostrils
- Only permit children to use personal diffusers that have been designed with safety features that include low ambient vapor concentration output and barriers to prevent skin and mucous membrane contact
- Always supervise children who are receiving TIEO