During the last decade, there has been a growing interest in aromatherapy, which uses essential oils as major therapeutic agents to improve a variety of health conditions (Aćimović, 2021; Ali et al., 2015). Nowadays, it is recognized as aroma science therapy (Esposito et al., 2014) and existing scientific studies suggest that aromatherapy is effective in reducing levels of anxiety and stress (Lee et al., 2011; Fellowes et a., 2008), depression (Firoozei et al., 2021; Sánchez-Vidaña et al., 2017), dental anxiety (Cai et al., 2021) and acute pain (Lamadah & Nomani, 2016; Mirzai et al., 2009; Tafazoli et al., 2011). In addition, aromatherapy has been proven effective in the treatment of sleep disorders (Cheong et al., 2021; Song et al., 2021), rheumatic diseases (Barão Paixão & De Carvalho, 2021), and has demonstrated anti-inflammatory effects (Ali et al., 2015; Park et al., 2014). Given those promising results, it is essential to know what aromatherapy is and how it can be used effectively.
In a wider sense, aromatherapy is defined as the therapeutic use of plant-derived concentrated essences which are extracted by distillation (Herz, 2009; Perry & Perry, 2006). It refers to the practice of using essential oils extracted from bark, flowers, stems, roots, leaves, or other parts of a plant to improve the physical and emotional well-being of the general population. Recently, different authors (Aćimović, 2021; Hermann et al, 2019) classified the essential oils used in aromatherapy in seven main groups, based on the aroma and particular smell of the oil.
Essential oils contain volatile natural compounds that are considered to exert a pharmacological effect by penetrating the body by oral, dermal (aromatherapy massage) (Buckle, 2003), and/or olfactory administration (inhalation aromatherapy) (de Groot & Schmidt, 2016). Thus, aromatherapy can be applied through three main methods:
Among them, inhalation aromatherapy is increasingly recognized as an accessible, easy-to-use, and effective method for stress relief and mood enhancement (Alexander, 2001). Although the exact neurological mechanisms of aromatherapy have not been established, and there are several differing results in the research in this field, inhaled air with essential oils:
Although inhaled aromatherapy cannot cure major illnesses, it has shown efficacy in reducing the levels of stress and anxiety in a variety of situations and conditions. Nowadays, a variety of controlled studies with strong research methodology and good samples sizes, have shown the utility of inhaled essential oils for stress relief and anxiety reduction in the general population (Haehner et al., 2017; Ndao et al., 2012; Seyyed-Rasooli et al., 2016; Tugut et al., 2017; Ueki et al., 2014), persons with cancer (Ozkaraman et al., 2018; Pimenta et al., 2016; Redd et al., 1994; Yayla & Ozdemir, 2019), cardiovascular disease (Fazlollahpour-Roni et al., 2019; Hasanzadeh et al., 2016; Moslemi et al., 2019; Najafi et al., 2014), chronic renal failure (Barati et al., 2016) or dental problems (Lehrner et al., 2000; 2005). Inhalation aromatherapy has also shown benefits during painful medical procedures like a diagnostic curettage (Bakhsha et al., 2014; Eslami et al., 2018; Dagli et al., 2019).
In this sense, the John Hopkins Medicine (2020) recommends to use of essential oils in these forms:
From the above studies, it is possible to conclude that essential oils are natural and non-invasive methods that can help to regulate the mood and the affect in humans. In contrast, some common alternatives can have detrimental effects on users’ health.
First, synthetic fragrances are made from chemicals of which 95% are derived from petroleum and include toluene, according to the Environmental Working Group (EWG). Precisely, toluene has adverse effects on the Central Nervous System (CNS), cardiovascular, hematopoietic, reproductive, and respiratory systems, as well as on the liver, kidneys, skin, and sensory organs after exposure to high concentrations (Kopelovich et al., 2015). Toluene can cause urothelial and bladder cancers (Adamowicz et al., 2019). Phthalate esters have been also identified in synthetic fragrances (U.S. Food and Drug Administration, 2020), which can also contribute to the development of urothelial cancer in patients with chronic kidney disease (Huan & Chou, 2018). Thus, several studies suggest that the use of synthetic fragrances can have important health risks for the consumers.
Second, recent studies have shown that scented candles, especially the cheaper varieties, can also have a negative impact on health. In particular, authors like Ahn et al. (2015) identified a total of 34 compounds in scented candles, including potentially carcinogenic formaldehyde and aromatic hydrocarbons such as toluene and benzopyrene. Thereby, it is important to note that scented candles release pleasant aromas but also toxic components before lighting (off) and when lit (on).
The use of synthetic fragrances and scented candles has been found to have serious consequences on health. Given this context, healthy alternatives include the use of unscented candles made of 100% beeswax or pure essential oils.
Finally, note that recent research studies have demonstrated the viability and the utility of combining essential oils with emergent technologies such as Virtual Reality (VR). In particular, the combination of aromatherapy and VR shows efficacy in improving the wellbeing of patients undergoing chemotherapy (Oyama et al., 2000), reducing the stress in the general population (Hedblom et al., 2019; Kaimal et al., 2020), and reducing stress and promoting a positive mood in older institutionalized adults (Cheng et al., 2020). Those studies suggest that aromatherapy, as an established therapeutic, can be combined with and made more efficacious through the use of the latest emerging technologies such as VR.
In addition, the use of essential oils during exposure to virtual scenarios could provide help in alleviating simulator sickness. This is a side effect that some VR-users can experience which is characterized by dizziness, sweating and, especially, nausea. The use of essential oils have been demonstrated to block the serotonin and dopamine receptors in the central nervous system involved in nausea (Ahmadi et al, 2020). After inhalation, essential oils are absorbed through the lungs, the nasotracheal mucosa and by the bloodstream and exert their effects by acting on the limbic system. Given this context, recent studies have shown the efficacy of inhalation aromatherapy in reducing the severity of nausea in a variety of conditions such as in surgical patients (Ahmadi et al., 2020; Ferruggiari et al., 2012), postoperative settings (Briggs et al., 2016; Fearrington et al., 2019), chemotherapy processes (Zorba & Ozdemir, 2018), acute care settings (Johnson et al., 2016), among others.
In particular, although more research is still needed, current studies suggest that essential oils like peppermint (Abdel Ghani & Ahmed Ibrahim, 2013; Ahmadi et al. 2020; Briggs et al., 2016; Fearrington et al., 2019; Lane et al., 2012; Tate, 1997), ginger (Ernst & Pittler, 2000; Fearrington et al., 2019; Hunt et al., 2013; Johnson et al., 2016: White, 2007) and lavender (Abdel Ghani & Ahmed Ibrahim, 2013) can be effective to reduce nausea. Researchers have been also using Essential Oils in a blend form, since they are believed to be more effective as the therapeutic value is caused by the reaction and balance of the essential oils constituents (Ryman, 1993). Thus, for example, Zorba & Ozdemir (2018) used a blend of peppermint, bergamot and cardamom, while Hunt et al. (2013) used a blend of peppermint, ginger, spearmint ,and cardamom. In a similar way, Ovayuly et al. (2014) used a blend of lavender, mint, chamomile, jasmine, violet, rosemary.
Those studies suggest that the use of inhalation essential oils may also prevent and alleviate nausea and dizziness in virtual worlds. However, specific research is still needed to explore the influence of essential oils on the simulator sickness experienced in immersive worlds.
Aćimović, M. (2021). Essential Oils: Inhalation Aromatherapy – A Comprehensive Review. Journal of Agronomy, Technology and Engineering Management, 4(2), 547-557. Available at: http://www.fimek.edu.rs/downloads/casopisi/jatem/issue/v4_2/01-(1)._Acimovic_2021_4(2)_547-557.pdf
Adamowicz, J., Juszczak, J., Poletajew, S., Van Breda, S.V., Pokrywczynska, M., & Drewa, T. (2019). Scented Candles as an Unrecognized Factor that Increases the Risk of Bladder Cancer; Is There Enough Evidence to Raise a Red Flag? Cancer Prevention Research, 12(10), 645-651. DOI: https://doi.org/10.1158/1940-6207.CAPR-19-0093
Ahmadi, Y., Rezaei, J., Rezaei, M. & Khatony, A. (2020). Comparison of the Effect of Inhalation Aromatherapy with 10% and 30% Peppermint Essential Oils on the Severity of Nausea in Abdominal Surgery Patients. Evidence-Based Complementary and Alternative Medicine, Article ID 5897465. DOI: https://doi.org/10.1155/2020/5897465
Ahn, J.H., Kim, K.H., Kim, Y.H. & Kim, B.W. (2015). Characterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit. Journal of Hazardous Materials, 9, 242-251. DOI: https://doi.org/10.1016/j.jhazmat.2014.12.040
Alexander, M. (2001). Aromatherapy and immunity: how the use of essential oils aid immune potentiality. Part 2: Mood-immune correlations, stress and susceptibility to illness and how essential oil odorants raise this threshold. The International Journal of Aromatherapy, 11, 152-156. DOI: https://doi.org/10.1016/S0962-4562(01)80051-5
Ali, B., Al-Wabel, N.A., Shams, S., Ahamad, A., Khan, S.A., & Anwar F. (2015). Essential oils used in aromatherapy: A systemic review. Asian Pacific Journal of Tropical Biomedicine, 5(8), 601-611. DOI: https://doi.org/10.1016/j.apjtb.2015.05.007
Bakhsha, F., Mazandarani, M., Aryaei, M., Jafari, S.Y., & Bayate, H. (2014). Phytochemical and anti-oxidant activity of Lavandula Angustifolia mill. Essential oil on preoperative anxiety in patients undergoing diagnostic curettage. International Journal of Women’s Health and Reproduction Sciences, 2(4), 268-271. DOI: https://doi.org/10.15296/ijwhr.2014.42
Barão Paixão, V.L. & de Carvalho, J.F. (2021). Essential oil therapy in rheumatic diseases: A systematic review. Complementary Therapies in Clinical Practice, 43, 101391. DOI: https://doi.org/10.1016/j.ctcp.2021.101391
Barati, F., Nasiri, A., Akbari, N., & Sharifzadeh, G. (2016). The effect of aromatherapy on anxiety in patients. Nephro-Urology, 8(5), e38347. DOI: https://doi.org/10.5812/numonthly.38347
Briggs, P., Hawrylack, H. & Mooney. R. (2016). Inhaled peppermint oil for postop nausea in patients undergoing cardiac surgery. Nursing, 46(7), 61–67. DOI: https://doi.org/10.1097/01.NURSE.0000482882.38607.5c
Buckle J. (2003). Clinical Aromatherapy: Essential oils in Practice. 2nd. New York, NY, USA: Churchill Livingstone Elsevier Science. Available from: https://www.elsevier.com/books/clinical-aromatherapy/buckle/978-0-7020-3645-3
Cai, H., Xi, P., Zhong, L., Chen, J., & Liang, X. (2021). Efficacy of aromatherapy on dental anxiety: A systematic review of randomised and quasi-randomised controlled trials. Oral Diseases, 27(4), 829-847. DOI: https://doi.org/10.1111/odi.13346
Cheng, V. Y-W., Huang, C-M., Liao, J-Y., Hsu, H-P., Wang, S-W., Huang, S-F., & Guo, J-L. (2020). Combination of 3-Dimensional Virtual Reality and Hands-On Aromatherapy in Improving Institutionalized Older Adults' Psychological Health: Quasi-Experimental Study. Journal of Medical Internet Research, 22(7):e17096. DOI: https://doi.org/10.2196/17096
Cheong, M.J., Kim, S., Kim, J.S., Lee, H., Lyu, Y-S., Lee, Y.R., Jeon, B. & Kang, H.W. (2021). A systematic literature review and meta-analysis of the clinical effects of aroma inhalation therapy on sleep problems. Medicine (Baltimore), 5;100(9):e24652. DOI: https://doi.org/10.1097/MD.0000000000024652
Dagli, R., Avcu, M., Metin, M., Kiymaz, S., & Ciftci, H. (2019). The effects of aromatherapy using rose oil (Rosa damascena Mill.) on preoperative anxiety: a prospective randomized clinical trial. European Journal of Integrative Medicine, 26, 37–42. DOI: https://doi.org/10.1016/j.eujim.2019.01.006
de Groot A. C. & Schmidt E. (2016). Essential oils, Part I. Dermatitis. 27(2), 39–42. DOI: https://doi.org/10.1097/der.0000000000000175
Ernst, E., & Pittler, M. (2000). Efficacy of ginger for nausea and vomiting: A systematic review of randomized clinical trials. British Journal of Anaesthesia, 84(3), 367-371. DOI: https://doi.org/10.1093/oxfordjournals.bja.a013442
Eslami, J., Ebrahimi, A., Hosseinkhani, A., Khazaei, Z., & Darvishi, I. (2018). The effect of aromatherapy using Lavender (Lavandula angustifolia Miller) and Citrus aurantium L. extracts to treat anxiety of patients undergoing laparoscopic cholecystectomy: a randomized clinical trial in Iran. Biomedical Research and Therapy, 5(3), 2096-2110. DOI: https://doi.org/10.15419/bmrat.v5i3.423
Esposito, E.R. Bystrek, M.V., & Klein, J. (2014). An elective course in aromatherapy science. American Journal of Pharmaceutical Education, 78(4), 79. DOI: https://doi.org/10.5688/ajpe78479
Fazlollahpour-Rokni, F., Shorofi, S.A., Mousavinasab, N., Ghafari, R., Esmaeili, R. (2019). The effect of inhalation aromatherapy with rose essential oil on the anxiety of patients undergoing coronary artery bypass graft surgery. Complementary Therapies in Clinical Practice, 34, 201-207. DOI: https://doi.org/10.1016/j.ctcp.2018.11.014
Fearrington, M.A., Qualls, B.W., & Carey, M.G. (2019). Essential Oils to Reduce Postoperative Nausea and Vomiting. Journal of Perianesthesia Nursing, 34(5), 1047-1053. DOI: https://doi.org/10.1016/j.jopan.2019.01.010
Firozeei, T.K. Feizi, A., Rezaeizadeh, H., Zargaran, A., Roohafza, H.R., & Karimi, M. (2021). The antidepressant effects of lavender (Lavandula angustifolia Mill.): A systematic review and meta-analysis of randomized controlled clinical trials. Complementary Therapies in Medicine, 59, 102679. DOI: https://doi.org/10.1016/j.ctim.2021.102679
Fellowes, D., Barnes, K., & Wilkinson, S.S. (2008). WITHDRAWN: Aromatherapy and massage for symptom relief in patients with cancer. The Cochrane Database of Systematic Reviews, 8(4):CD002287. DOI: https://doi.org/10.1002/14651858.CD002287.pub3
Haehner, A., Maass, H., Croy, I., & Hummel, T. (2017). Influence of room fragrance on attention, anxiety and mood. Flavour and Fragrance Journal, 32(1), 24-28.DOI: https://doi.org/10.1002/ffj.3339
Hasanzadeh, F., Kashouk, N.M., Amini, S., Asili, J., Emami, S.A., Vashani, H.B., & Sahebkar, A: (2016). The effect of cold application and lavender oil inhalation in cardiac surgery patients undergoing chest tube removal.EXCLI Journal, 15, 64-74. DOI: https://doi.org/10.17179/excli2015-748
Hedblom, M., Gunnarsson, B., Iravani, B., Knez, I., Schaefer, M., Thorsson, P., & Lundström, J.N. (2019). Reduction of physiological stress by urban green space in a multisensory virtual experiment. Scientific Reports, 9, 10113. DOI: https://doi.org/10.1038/s41598-019-46099-7
Herman, R.A., Ayepa, E., Shittu, S., Fometu, S.S. & Wang, J. (2019). Essential oils and their applications -a mini review. Advances in Nutrition and Food Science, 4(4), 1-13. DOI: https://doi.org/10.33140/anfs.04.04.08
Herz R. S. (2009). Aromatherapy facts and fictions: a scientific analysis of olfactory effects on mood, physiology and behavior. International Journal of Neuroscience, 119(2), 263–290. DOI: https://doi.org/10.1080/00207450802333953
Huan, C.C., & Chou, C.Y. (2018). Higher phthalate exposure may increase risk of urothelial cancer in patients with chronic kidney disease. Nephrology Dialysis Transplantation, 33(suppl_1), Page i447. DOI: https://doi.org/10.1093/ndt/gfy104.SP306
Hunt, R., Dienemann, J., Norton, H.J., Hartley, W., Hudgens, A., Stern, T., & Divine, G. (2013). Aromatherapy as treatment for postoperative nausea. Anesthesia & Analgesia, 117(3), 597-604. DOI: https://doi.org/10.1213/ANE.0b013e31824a0b1c
John Hopkins Medicine (2020). Aromatherapy: Do Essential Oils Really Work?. Available at: https://www.hopkinsmedicine.org/health/wellness-and-prevention/aromatherapy-do-essential-oils-really-work
Johnson, J.R., Rivard, R.L., Griffin, K.H., Kolste, A.K., Joswiak, D., Kinney, M.E., & Dusek, J.A: (2016). The effectiveness of nurse-delivered aromatherapy in an acute care setting. Complementary Therapies in Medicine, 25, 164-169. DOI: https://doi.org/10.1016/j.ctim.2016.03.006
Kaimal, G., Carroll-Haskins, K., Ramakrishnan, A., Magsamen, S., Arslanbek, A. & Herres, J. (2020). Outcomes of Visual Self-Expression in Virtual Reality on Psychosocial Well-Being With the Inclusion of a Fragrance Stimulus: A Pilot Mixed-Methods Study. Frontiers in Psychology. DOI: https://doi.org/10.3389/fpsyg.2020.589461
Kopelovich, L., Perez, A.L., Jacobs, N., Mendelsohn, E., & Keenan, J.J. (2015). Screening-level human health risk assessment of toluene and dibutyl phthalate in nail lacquers. Food and Chemical Toxicology, 81, 46-53. DOI: https://doi.org/10.1016/j.fct.2015.04.011
Lamadah, S.M., & Nomani, I. (2016). The effect of aromatherapy massage using lavender oil on the level of pain and anxiety during labour among primigravida women. American Journal of Nursing Science, 5(2), 37-44. DOI: https://doi.org/10.11648/j.ajns.20160502.11
Lane, B., Cannella, K., Bowen, C., Copelan, D., Nteff, G., Barnes, K., Poudevigne, M., & Lawson, J. (2012). Examination of the effectiveness of peppermint aromatherapy on nausea in women post C-section. Journal of Holistic Nursing, 30(2), 90-106. DOI: https://doi.org/10.1177/0898010111423419
Lee, Y.L., Wu, Y., Tsang, H.W., Leung, A.Y., & Cheung, W.M. (2011). A systematic review on the anxiolytic effects of aromatherapy in people with anxiety symptoms. Journal of Alternative and Complementary Medicine, 17(2), 101-108. DOI: https://doi.org/10.1089/acm.2009.0277
Lehrner, J., Eckersberger, C., Walla, P., Potsch, G., & Deecke, L. (2000). Ambient odor of orange in a dental office reduces anxiety and improves mood in female patients. Physiology & Behavior, 71(1-2), 83–86. DOI: https://doi.org/10.1016/S0031-9384(00)00308-5
Lehrner, J., Marwinski, G., Lehr, S., Johren, P., & Deecke, L. (2005). Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office. Physiology & Behavior, 86(1–2), 92–95. DOI: https://doi.org/10.1016/j.physbeh.2005.06.031
Lv, X.N., Liu, Z.J., Zhang, H.J. & Tzeng, C.M. (2013). Aromatherapy and the central nerve system (CNS): therapeutic mechanism and its associated genes. Current Drug Targets, 14(8), 872-879. DOI: https://doi.org/10.2174/1389450111314080007
Mirzai, F., Keshtgar, S., Kaviani, M., & Rejaefard, A.H. (2009). The effect of lavender essence smelling during labor on cortisol and serotonin plasma levels and anxiety reduction in nulliparous women. Journal of Kerman University of Medical Sciences, 16(3), 245-254. Available at: https://iranjournals.nlai.ir/bitstream/handle/123456789/249208/55B0747916393C2CFDFD48180E565138.pdf
Moslemi, F., Alijaniha, F., Naseri, M., Kazemnejad, A., Charkhkar, M., & Heidari, M.R. (2019). Citrus aurantium aroma for anxiety in patients with acute coronary syndrome: a double-blind placebo-controlled trial. Journal of Alternative and Complementary Medicine (New York, N.Y.), 25(8), 833-839. DOI: https://doi.org/10.1089/acm.2019.0061
Najafi, Z., Taghadosi, M., Sharifi, K., Farrokhian, A., & Tagharrobi, Z. (2014). The effects of inhalation aromatherapy on anxiety in patients with myocardial infarction: a randomized clinical trial. Iran Red Crescent Medical Journal, 16(8), e15485. DOI: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4222007/
Ndao, D.H., Ladas, E.J., Cheng, B, Sands, S.A., Snyder, K.T., Garvin, J.H. & Kelly, K.M. (2012). Inhalation aromatherapy in children and adolescents undergoing stem cell infusion: results of a placebo-controlled doubleblind trial. Psychooncology 21(3), 247–254. DOI: https://doi.org/10.1002/pon.1898
Ovayolu O., Sevig U., Ovayolu N., & Sevinc A. (2014). The effect of aromatherapy and massage administered in different ways to women with breast cancer on their symptoms and quality of life. International Journal of Nursing Practice, 20(4), 408-417. DOI: https://doi.org/10.1111/ijn.12128
Oyama, H., Kaneda, M., Katsumata, N., Akechi, T., & Ohsuga, M. (2000). Using the Bedside Wellness System During Chemotherapy Decreases Fatigue and Emesis in Cancer Patients. Journal of Medical Systems, 24(3), 173-182. DOI: https://doi.org/10.1023/a:1005591626518
Ozkaraman, A., Dugum, O., Ozen Yilmaz, H. & Usta Yesilbalkan, O. (2018). Aromatherapy: the effect of lavender on anxiety and sleep quality in patients treated with chemotherapy. Clinical Journal of Oncology Nursing, 22(2), 203-210. DOI: https://doi.org/10.1188/18.CJON.203-210
Park, S.Y.; Neupane, G.P.; Lee, S.O.; Lee, J.S.; Kim, M.Y.; Kim, S.Y.; Park, B.C.; Park, Y.J.; Kim, J.A. (2014). Protective effects of Pogostemon cablin Bentham water extract on inflammatory cytokine expression in TNBS-induced colitis in rats. Archives of Pharmacal Research, 37(2), 253-262. DOI: https://doi.org/10.1007/s12272-013-0260-x
Perry N. & Perry E. (2006). Aromatherapy in the management of psychiatric disorders: clinical and neuropharmacological perspectives. CNS Drugs, 20(4), 257–280. DOI: https://doi.org/10.2165/00023210-200620040-00001
Pimenta, F.C., Alves, M.F., Pimenta, M.B., Melo, S.A.L., de Almeida, A.A.F., Leite, J.R., Pordeus, L.C.M., Diniz, M.F.F.M., & de Almeida, R.N. (2016). Anxiolytic effect of citrus aurantium L. on patients with chronic myeloid leukemia. Phytotherapy Research, 30(4), 613-617. DOI: https://doi.org/10.1002/ptr.5566
Redd, W.H., Manne, S.L., Peters, B., Jacobsen, P.B., & Schmidt, H. (1994). Fragrance administration to reduce anxiety during MR imaging. Journal of Magnetic Resonance Imaging, 4(4), 623-626. DOI: https://doi.org/10.1002/jmri.1880040419
Ryman, D. (1993) Aromatherapy: The Complete Guide to Plant and Flower Essences for Health and Beauty. New York: Bantam Books.
Sánchez-Vidaña, D.I., Ngai, S, P-C., He, W., Chow, J K-W., Lau, B W-M., & Tsang, H. W-H. (2017). The Effectiveness of Aromatherapy for Depressive Symptoms: A Systematic Review. Evidence-Based Complementary and Alternative Medicine, Article ID 5869315. DOI: https://doi.org/10.1155/2017/5869315
Seyyed-Rasooli, A., Salehi, F., Mohammadpoorasl, A., Goljaryan, S., Seyyedi, Z., & Thomson, B. (2016). Comparing the effects of aromatherapy massage and inhalation aromatherapy on anxiety and pain in burn patients: a single-blind randomized clinical trial. Burns, 42(8), 1774–1780. DOI: https://doi.org/10.1016/j.burns.2016.06.014
Song, X., Jiahua, P., Weiyu, J., Minghua, Y., & Lisheng, J. (2021). Effects of aromatherapy on sleep disorders. A protocol for systematic review and meta-analysis. Medicine (Baltimore), 100(17), e25727. DOI: https://doi.org/10.1097/MD.0000000000025727
Tafazoli, M., Zaremobini, F., Mokhber, N., Emami, A. (2011). The Effect of lavender oil Inhalation on the level of anxiety during first stage of labor in primigravida women. Journal of Fundamentals of Mental Health, 12(4), 720–726. DOI: https://doi.org/10.22038/JFMH.2010.1035
Tate, S. (1997). Peppermint oil: a treatment for postoperative nausea.Journal of Advanced Nursing, 26(3), 543-549. DOI: https://doi.org/10.1046/j.1365-2648.1997.t01-15-00999.x
Tugut, N., Demirel, G., Baser, M., Ata, E.E., & Karakus, S. (2017). Effects of lavender scent on patients’ anxiety and pain levels during gynecological examination. Complementary Therapies in Clinical Practice, 28, 65-69. DOI: https://doi.org/10.1016/j.ctcp.2017.05.006
Ueki, S., Niinomi, K., Takashima, Y., Kimura, R., Komai, K., Murakami, K., & Fujiwara, C. (2014). Effectiveness of aromatherapy in decreasing maternal anxiety for a sick child undergoing infusion in a paediatric clinic. Complementary Therapies in Medicine, 22(6), 1019–1026. DOI: https://doi.org/10.1016/j.ctim.2014.09.004
U.S Food & Drug (2020). Fragrances in Cosmetics. Available at: https://www.fda.gov/cosmetics/cosmetic-ingredients/fragrances-cosmetics
White, B. (2007). Ginger: An overview. American Family Physician, 75(11), 1689–1691. Available at: https://www.aafp.org/afp/2007/0601/p1689.html
Yayla, E.M., & Ozdemir, L. (2019). Effect of inhalation aromatherapy on procedural pain and anxiety after needle insertion into an implantable central venous port catheter: a quasi-randomized controlled pilot study. Cancer Nursing, 42(1), 35-41. DOI: https://doi.org/10.1097/NCC.0000000000000551
Zorba, P., & Ozdemir, L. (2018). The preliminary effects of massage and inhalation aromatherapy on chemotherapy-induced acute nausea and vomiting. Cancer Nursing, 41(5), 359–366. DOI: https://doi.org/10.1097/NCC.0000000000000496