Background: Considering the prevalence of mental health problems in older adults, this study aims to investigate the effect of inhalation aromatherapy using lavender and chamomile essential oils on depression, anxiety, and stress of community-dwelling older people.

Methods: A three-armed, parallel, randomized, and controlled trial design was used in this study. 183 participants were enrolled and randomly assigned to three groups (n = 61): the lavender, chamomile, and control groups. The participants in the experimental groups inhaled three drops of 1.5% lavender and chamomile essential oils for 30 nights. The participants in the control group inhaled only distilled water in a similar fashion. Data were collected using the Depression, Anxiety, and Stress-Scale (DASS) at baseline, immediately after the intervention, and one month after the intervention. Chi-square, Fisher's exact, one-way ANOVA, and repeated measures ANOVA were used for data analysis.

Results: Statistically significant improvement occurred in depression, anxiety, and stress levels immediately and one month after the intervention in lavender and chamomile groups compared to the control group (p < 0.01).

Conclusion: Inhalation aromatherapy with both lavender and chamomile essential oils helped decrease depression, anxiety, and stress levels in community-dwelling older adults.