Objectives: To determine the effect of post-extubation oral menthol lozenges on thirst, nausea, physiological parameters, and comfort level in patients undergoing cardiovascular surgery.Research methodology/design: The study was a single-centre, randomized controlled trial.Setting: This study included 119 patients undergoing coronary artery bypass graft surgery in a training and research hospital. Patients in the intervention group (n = 59) received menthol lozenges at 30, 60, and 90 min after extubation. Patients in the control group (n = 60) received standard care and treatment.Main outcome measures: The primary outcome of the study was the change in post-extubation thirst assessed by Visual Analogue Scale after using menthol lozenges compared to baseline. Secondary outcomes were changes in post-extubation physiological parameters and nausea severity assessed by Visual Analogue Scale compared to baseline, and comfort level assessed with Shortened General Comfort Questionnaire.Results: Between-group comparisons showed that the intervention group had significantly lower thirst scores at all time points and nausea at the first assessment (p < 0.05) and significantly higher comfort scores (p < 0.05) than the control group. There were no significant differences between the groups in physiological parameters at baseline or any of the postoperative assessments (p > 0.05).Conclusion: In patients undergoing coronary artery bypass graft surgery, the use of menthol lozenges effectively increased comfort level by reducing post-extubation thirst and nausea, but had no effect on physiological parameters.Implications for clinical practice: Nurses should be vigilant for complaints such as thirst, nausea, and discomfort in patients after extubation. Nurses' administration of menthol lozenges to patients may help reduce post-extubation thirst, nausea, and discomfort.