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

The goal of this clinical trial is to evaluate whether aromatherapy inhaler sticks can reduce nausea and vomiting in patients receiving chemotherapy as part of their stem cell transplant treatment. The main questions it aims to answer are: * Can aromatherapy inhaler sticks be practically used by patients undergoing stem cell transplant (feasibility)? * Do patients find aromatherapy inhaler sticks acceptable to use during their treatment? * How effective are aromatherapy inhaler sticks at reducing chemotherapy-induced nausea and vomiting? * What are patients' experiences when using aromatherapy during stem cell transplant? Researchers will compare patients using aromatherapy inhaler sticks with essential oils to patients using inhaler sticks with only jojoba oil (placebo) to see if the essential oils provide additional benefits for reducing nausea and vomiting. Participants will: * Use their assigned inhaler stick every four hours when awake and whenever they feel nauseous * Hold the inhaler stick a finger's length from their nostrils and inhale through one nostril at a time * Use the inhaler stick for no more than 5 minutes per session * Begin using the inhaler on the day of chemotherapy and continue until five days after chemotherapy completion (total of six days) * Receive standard care for nausea and vomiting alongside the inhaler stick * Complete study journals to record their experiences This is a single-blinded study, meaning participants will not know whether they received the aromatherapy or placebo inhaler stick.