Your response was formulated by Drs. Diana Balekian and Aidan Long of the Massachusetts General Hospital and Harvard Medical School.
There are no published studies specifically examining the effects of diffused essential oils on asthma. However, there have been data published on the release of volatile organic compounds (VOCs) from diffused essential oils (Su HJ et al, 2007; Chiu HH et al., 2009). These studies have found that diffused essential oils such as lavender, eucalyptus, and tea tree, were found to release terpenes, toluene, and benzene, among other VOCs, into the air. Terpenes have been associated with increased nocturnal breathlessness, bronchial hyperresponsiveness, and peak expiratory flow variability among patients with and without asthma (Norback et al, 1995). Anecdotally, there have been reports of respiratory symptoms in asthmatics and non-asthmatics due to a variety of diffused essential oils.
One of the hallmarks of asthma, especially during episodes of sub-optimal control, is non-specific bronchial hyperactivity, where airborne irritants can trigger bronchospasm. Given this information, I would recommend that patients exercise caution when using essential oil diffusers. Though these oils are “natural”, they release VOCs which have been associated with increased asthma symptoms.
I hope this information is of help to you and your patient care.
All our best.
Diana Balekian MD
Aidan Long MD
Dennis K. Ledford, MD, FAAAAI
Chiu, HH, Chiang HM, Lo CC, et al. Constituents of volatile organic compounds of evaporating essential oil. Atmospheric Environment. 2009;43:5743-5749
Norback D, Bjornsson E, Janson C, et al. Asthmatic symptoms and volatile organic compounds, formaldehyde, and carbon dioxide in dwellings. Occupational and Environmental Medicine. 1995;52:388-395
Su HJ, Chao CJ, Chang HY, Wu PC. The effects of evaporating essential oils on indoor air quality. Atmospheric Environment. 2007;41:1230-1236