The Effect of a Protective Oral Care Protocol Using Peppermint Oil Mouthwash

Hematologic malignancies are the fifth most common type of cancer in the world. Patients with hematologic malignancies receive long-term and exhausting treatments such as chemotherapy, radiotherapy, hematopoietic stem cell transplantation and supportive therapies. Chemotherapy-induced nausea and vomiting has a significant impact on the daily lives of patients and causes physiological effects such as anorexia, malnutrition, weight loss, dehydration and electrolyte imbalance. It also has a negative impact on activities of daily living and psychological status, and may lead to poor adherence to chemotherapy regimens, refusal of chemotherapy or discontinuation of treatment. Oral mucosa is one of the areas most affected by the cytotoxic damage of chemotherapy. Disruption of the oral mucosa causes nausea, vomiting and feeding problems. Patients resort to non-drug approaches to manage these problems. It is important that these non-pharmacologic approaches are supported and controlled by reliable and evidence-based studies in order to prevent adverse effects on patient outcomes. In the literature, it has been determined that peppermint oil has antiemetic, antiseptic, anti-inflammatory, analgesic, antiseptic, antioxidant, antiviral, antifungal and spasmolytic effects, protects the integrity of the oral mucosa and has positive effects on nausea-vomiting and anorexia.

In this context, the aim of the study was to investigate the effect of a preventive oral care protocol with peppermint oil mouthwash on chemotherapy-induced nausea, vomiting and appetite in patients with hematologic malignancy.

Research Hypotheses H01: The protective oral care protocol applied with peppermint oil in patients with hematological malignancies has no effect on the development of chemotherapy-induced nausea and vomiting.

H02: The protective oral care protocol applied with peppermint oil in patients with hematological malignancies has no effect on the severity of chemotherapy-induced nausea and vomiting.

H03: The protective oral care protocol applied with peppermint oil in patients with hematological malignancies has no effect on the development of chemotherapy-induced anorexia.

H04: The protective oral care protocol applied with peppermint oil in patients with hematological malignancies has no effect on the severity of chemotherapy-induced anorexia.

Methods: The type of study is a single-blind randomized controlled experimental study. The research will be conducted between September 10, 2025, and April 10, 2026, with patients admitted to the hematology clinic of a university hospital for chemotherapy treatment. The study will be conducted with a total of 72 people who will be randomly assigned to the intervention (n=36) and control groups (n=36) by stratified and block randomization method. Patients who are 18 years of age or older, have hematologic malignancy, with a history of at least one chemotherapy cycle, and scheduled to receive chemotherapy with high or moderate emetogenic risk agents, do not have oral mucositis before chemotherapy, do not have metastasis, are literate and volunteer to participate in the study will be included in the study. Research data will be collected using the "Patient Introduction Form", "Rhodes Nausea-Vomiting and Retching Index", "Oral Assessment Guide", "Appetite Assessment Chart \[(Visual Analog Scale (VAS)\]", "Peppermint Oil Protective Oral Care Protocol", "Food Intake Record Form", "Allergic Reaction Monitoring Form" and "Patient Monitoring Form and Antiemetic Record Chart". In addition to the routine protective oral care (saline solution mouthwash and/or sodium bicarbonate mouthwash) in the clinic, "Peppermint Oil Protective Oral Care Protocol" will be applied to the intervention group for 6 days from the start of chemotherapy treatment. Patients will receive mouthwash prepared with 1 ml of peppermint oil and 50 ml of prepared drinking water 3 times a day. Patients in the intervention group will be monitored for 6 days by evaluating oral assessment, development of oral mucositis, appetite follow-up and compliance with mouthwash. The development of allergy due to the use of peppermint oil in each mouthwash application will be evaluated. The control group will not receive any oral care intervention by the researcher and will receive routine preventive oral care in the clinic. In the evaluation of the data, descriptive statistics, Chi-square / Fisher's Exact test will be used for the relationship between categorical variables, Mann Whitney U test, Wilcoxon test, Kruskal-Wallis H test will be used for the relationship between continuous variables in groups that do not show normal distribution; one-way analysis of variance / repeated measures analysis of variance, t test for dependent and independent groups will be used in groups with normal distribution. Correlation analysis and regression analysis will be used to examine the relationship between variables.