The purpose of this phase III randomized double-blinded controlled trial was to investigate the efficacy of a rose geranium in sesame oil (RG) nasal spray compared with an isotonic saline (IS) nasal spray for alleviating nasal vestibulitis symptoms among patients undergoing chemotherapy. Patients undergoing active chemotherapy who reported associated nasal symptoms were randomized 1:1 to receive RG or IS, administered twice daily for 2 weeks. Consenting participants completed nasal symptom questionnaires at baseline and then weekly while on treatment. The proportion of patients experiencing improvements in their nasal symptoms 2weeks after initiating the nasal spray, using a six-point global impression of change score, was estimated within and between each randomized arm, and compared between arms, using Fisher's exact test. The estimated odds ratio was determined (95% confidence interval). One hundred and six patients consented to this study; 43 participants in the RG arm and 41 in the IS arm were evaluable for the primary endpoint. Participants had a mean age of 57.8years (SD 13.9). Demographic characteristics and baseline nasal symptoms were similar between arms. Of the evaluable participants who received RG, 67.4% reported improved nasal symptoms, compared with 36.6% of the participants who received IS (P = 0.009). Adverse events were sparse and did not differ between arms. Rose geranium in sesame oil significantly improves nasal vestibulitis symptoms among patients undergoing chemotherapy. NCT04620369.