Essential Oil Inhalation and Acute Stress Response in Healthy Adults (DMA)

Evaluation of Aromatic Essential Oils in Conditions of Stress and Relaxation - A Double-Blind, Randomized, Placebo-Controlled Trial

This randomized, double-blind, placebo-controlled study evaluates the acute physiological and subjective responses to essential oil inhalation in healthy adults. Participants are assigned to inhale either an essential oil or a placebo via an aroma stick during standardized laboratory procedures designed to induce temporary psychosocial stress (Trier Social Stress Test - Group version) and during a guided relaxation session.

Physiological responses, including heart rate, heart rate variability, and electrodermal activity, are measured using a wearable sensor. Subjective stress and affect are assessed using validated questionnaires and visual analog scales. The purpose of this study is to characterize short-term autonomic and self-reported responses associated with essential oil inhalation under controlled experimental conditions. This study is exploratory and is not intended to diagnose, treat, or prevent any medical condition.

Study Overview

• Status: Active, not recruiting
• Conditions: Psychological Stress
• Intervention / Treatment: Other: Essential Oil Inhalation; Other: Placebo Aroma Stick

Detailed Description

Essential oils and essential oil blends are widely used in non-clinical settings; however, objective data describing short-term physiological and subjective responses to inhalation under controlled experimental conditions remain limited. This study is designed to evaluate acute autonomic and self-reported responses to essential oil inhalation during standardized laboratory procedures involving psychosocial stress and guided relaxation.

This is a randomized, double-blind, placebo-controlled, parallel-group study conducted in healthy adults aged 18-45 years. Participants are assigned to inhale either an essential oil (or essential oil blend) or a placebo comparator administered via an identical aroma stick. Inhalation occurs at standardized time points during two study visits.

During Study Visit 1, participants undergo the Trier Social Stress Test - Group version (TSST-G), a validated laboratory paradigm designed to induce temporary psychosocial stress through public speaking and mental arithmetic tasks performed under observation. Inhalation occurs during baseline, preparation, stress, and recovery phases. During Study Visit 2, participants undergo a structured guided meditation session under controlled environmental conditions, with inhalation occurring at standardized intervals.

Physiological measures are collected continuously using a wrist-worn wearable device capable of measuring heart rate, heart rate variability (HRV), and electrodermal activity (EDA). Subjective responses are assessed using validated instruments including visual analog scales for stress and calm, PROMIS Anxiety, GAD-7, and PANAS. The primary outcome is change in stress response as measured by area under the curve (AUC) for visual analog scale stress scores across the stress and recovery period.

The study employs an adaptive design with an initial planned enrollment of 100 participants (50 per arm) and a prespecified interim analysis for potential expansion to a maximum of 200 participants. Statistical analyses include comparison of stress and physiological responses between groups using baseline-adjusted models.

This study is exploratory in nature and is intended to characterize acute responses associated with essential oil inhalation under controlled conditions. It is not designed to diagnose, treat, mitigate, or prevent any disease or medical condition.

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Utah
    • Pleasant Grove, Utah, United States, 84062
      • dōTERRA International

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Age 18-45 years, inclusive

Able to read, write, and understand English

Willing and able to provide informed consent

Willing to attend two in-person study visits

Generally healthy, as determined by medical history and screening review

Exclusion Criteria:

Known asthma, chronic obstructive pulmonary disease (COPD), significant lung disease, heart disease, or other medical condition that may compromise safety or data integrity

Pregnancy or pregnancy within the past 90 days

Known allergy or sensitivity to essential oils or study placebo materials

Current smoking, vaping, chewing tobacco, or use of recreational drugs

Regular use of essential oils applicable to the study phase (>3 times per week for ≥2 weeks within the past month) without a minimum 1-month washout

Unwillingness to abstain from alcohol for at least 72 hours prior to each study visit

Failure to meet inclusion criteria

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Essential Oil Inhalation; Participants inhale an essential oil or essential oil blend via an individual aroma stick during standardized stress induction (TSST-G) and guided relaxation procedures across two study visits.	Other: Essential Oil Inhalation; Participants inhale an essential oil or essential oil blend administered via an individual aroma stick. At prespecified time points during baseline, stress induction (Trier Social Stress Test - Group version), and recovery or guided meditation procedures, participants are instructed to take five normal breaths from the aroma stick. The intervention is delivered in a randomized, double-blind manner and is standardized across participants within each study phase.
Placebo Comparator: Placebo Inhalation; Participants inhale a placebo aroma stick matched in appearance and delivery method but without active essential oil components during identical stress and relaxation procedures.	Other: Placebo Aroma Stick; Participants inhale a placebo comparator administered via an aroma stick identical in appearance and delivery method to the experimental intervention but without active essential oil components. The inhalation schedule and procedures are identical to those used in the experimental arm to maintain blinding.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Visual Analog Scale (VAS) Stress Area Under the Curve (AUC)	Area under the curve (AUC) for self-reported stress measured using a Visual Analog Scale (VAS) across baseline, stress induction (Trier Social Stress Test - Group version), and post-stressor recovery periods. The VAS-stress scale ranges from low stress to high stress, with higher scores indicating greater perceived stress.	Baseline through 30 minutes post-stressor recovery (Study Visit 1)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Heart Rate During Stress and Recovery	Mean heart rate measured using a wearable sensor during baseline, stress induction (Trier Social Stress Test - Group version), and post-stressor recovery. A higher heart rate, measured beats per minute (BPM), indicates higher stress.	Baseline through 30 minutes post-stressor recovery (Study Visit 1), approximately 90 minutes from baseline
Change in Electrodermal Activity During Stress and Recovery	Tonic electrodermal activity measured using a wearable sensor during baseline, stress induction, and recovery periods. This is measured in microsiemens, which is the SI unit of conductance. Higher tonic ectodermal activity indicates higher stress.	Baseline through 30 minutes post-stressor recovery (Study Visit 1), approximately 90 minutes from baseline.
Change in PROMIS Anxiety Scores	PROMIS Anxiety short form scores collected at baseline and during post-stressor recovery to assess subjective anxiety symptoms. A higher score indicates higher anxiety. The measurement scale ranges from 1 ("never") to 5 ("always").	Baseline and post-stressor recovery (Study Visit 1), approximately 90 minutes from baseline.
Change in Positive and Negative Affect Schedule (PANAS) Scores	PANAS scores assessing positive and negative affect collected at baseline and post-stressor recovery. The rating scale ranges from 1 ("Very slightly or not at all") to 5 ("extremely"). Higher scores with regard to the positive affect questions indicate greater levels of joy, enthusiasm, and active engagement. Higher scores with regard to the negative affect questions indicate higher levels of fear, anger, or distress.	Baseline and post-stressor recovery (Study Visit 1), approximately 90 minutes from baseline
Change in Visual Analog Scale (VAS) Calm Scores	Self-reported calmness measured using a visual analog scale across baseline, stress, and recovery phases. It is measured on a score of 0 to 100, with 0 representing "Not at all", and 100 representing "extremely".	Baseline through 30 minutes post-stressor recovery (Study Visit 1), approximately 90 minutes after baseline.
Incidence of Adverse Events	Number and severity of participant-reported adverse events occurring during study visits.	Through completion of Study Visit 2, up to 1 week post baseline.

Collaborators and Investigators

• Sponsor: dōTERRA International
• Investigators: Principal Investigator: Nicole Stevens, PhD, DoTERRA International LLC.

Study record dates

Study Major Dates

• Study Start (Actual): March 10, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: March 9, 2026
• First Submitted That Met QC Criteria: March 12, 2026
• First Posted (Actual): March 16, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Autonomic Nervous System; Stress; anxiety; acute stress; Aromatherapy; Essential Oils; Stress Reactivity
• Additional Relevant MeSH Terms: Mental Disorders; Behavioral Symptoms; Behavior; Anxiety Disorders; Stress, Psychological
• Other Study ID Numbers: DO-126042-DMA

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No