Evaluating the Feasibility and Acceptability of Inhalation Aromatherapy for Patients Undergoing Autologous Haematopoietic Stem Cell Transplant (HSCT)

Participants in the intervention group will receive inhalation therapy via an aromatherapy inhaler stick\*, on top of standard care. They will be instructed to use the inhaler stick every four hours when they are awake, and whenever they feel nauseous, by holding the inhaler stick a finger's length away from their nostrils and inhaling through one nostril at a time. Each administration should not last more than 5 minutes. Participants will commence using the inhaler stick on the day of chemotherapy, until five days after the completion of chemotherapy (total of six days). Given the subjective nature of scents, participants in the intervention group will be given a choice between two therapeutic aroma blends - N1 and N2 - before commencing the study. This approach aims to minimize the risk of negative associations with a particular scent and enhance participant adherence to the intervention.

Participants in the control group will receive the placebo intervention in addition to standard care. They will be provided with an identical aromatherapy inhaler stick infused solely with jojoba oil. Jojoba oil, primarily used as a carrier oil for dilution, has littleto- no scent and no known therapeutic or anxiolytic effects when inhaled.