The effects of olfactory stimulation on postural control in adults: A systematic review

Olfactory stimulation has emerged as a potential modulator of postural control, yet the evidence has not been systematically synthesized. This systematic review aimed to aggregate, critically appraise, and narratively synthesize the available literature on the effects of olfactory stimulation on postural control in adults.

This systematic review was conducted according to the PRISMA 2020 guideline and the Cochrane Handbook. The protocol was registered with PROSPERO (CRD420261326528). A systematic search of PubMed, Web of Science, and Scopus was performed from inception to December 1, 2025, supplemented by grey literature searches and reference list screening. Randomized controlled trials (RCTs), quasi-experimental designs, and clinical trials examining olfactory stimulation effects on any quantitative measure of postural control were eligible. Two reviewers independently performed study selection, data extraction, and quality assessment using the Downs and Black checklist. The certainty of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework. Due to substantial methodological and clinical heterogeneity, a narrative synthesis was conducted following the Synthesis Without Meta-analysis (SWiM) guidelines.

Ten studies (six RCTs and four Non-RCTs) involving 365 participants (mean age 47.9 ± 19.8 years) were included. Olfactory stimulation with pleasant odors (e.g., lavender, black pepper) generally enhanced postural stability, particularly in older adults and under eyes-closed conditions, while unpleasant odors consistently increased postural sway. However, inhibitory effects were observed during high-precision athletic tasks. Odor-specific effects were identified, with appetitive cues producing unique facilitatory effects. According to GRADE, the certainty of evidence was moderate for dynamic balance and functional mobility, low for fear of falling, and very low for static balance.

Olfactory stimulation can modulate postural control in adults, with effects dependent on odor valence, participant traits, and task demands. Pleasant odors generally enhance stability during sensory deprivation, while unpleasant odors increase sway; however, trigeminal stimulants like ammonia may impair high-precision tasks. Evidence certainty was low to moderate, warranting cautious interpretation. These findings lay the groundwork for future research on olfactory-motor integration and clinical applications in balance rehabilitation and fall prevention. Registration: The study was registered on the International Prospective Registry of Systematic Reviews database (CRD420261326528).