Effects of Lavender Inhalation Aromatherapy on Depression in Individuals Undergoing Drug Treatment for Substance...

Depression is common among individuals undergoing treatment for substance dependence and may adversely affect outcomes. This study determined the short-term effect of lavender aromatherapy on depressive symptoms in individuals undergoing treatment for substance dependence.

This single-blind, parallel-group randomized clinical trial was conducted in residential addiction treatment centers in Isfahan, Iran, in 2025. Using convenience sampling, 56 participants were allocated to intervention (n = 28) and control (n = 28) groups by computer-generated block randomization with a 1:1 ratio. Allocation concealment was maintained with sequentially numbered, opaque, sealed envelopes. The intervention group received lavender inhalation aromatherapy twice daily for three consecutive days, plus routine treatment and care, whereas the control group received routine treatment and care only. Depression was measured using the DASS-21 depression subscale before and immediately after the intervention. Data were analyzed using IBM SPSS Statistics version 26.

Baseline depression scores were not significantly different between groups (14.71 ± 5.50 vs. 13.11 ± 5.94; mean difference = 1.61, 95% CI: -1.46 to 4.67; Cohen's d = 0.28; p = 0.30). After the intervention, depression scores were lower in the intervention group than in the control group (5.11 ± 3.75 vs. 12.29 ± 6.17; mean difference = -7.18, 95% CI: -9.91 to -4.44; Cohen's d = -1.41; p < 0.001).

Lavender inhalation aromatherapy was associated with a significant short-term reduction in depressive symptoms among individuals undergoing drug treatment for substance dependence. Given the short intervention period, immediate assessment, absence of follow-up, lack of placebo or attention control, and self-report outcome measure, findings should be interpreted cautiously and not as definitive evidence of durable or specific clinical efficacy. Longer trials with follow-up and appropriate comparators are needed.