Background: This study is aimed at determining the efficacy of Mentha spicata (M. spicata) and Mentha × piperita (M. × piperita) in preventing chemotherapy-induced nausea and vomiting (CINV).

Methods: This was a randomised, double-blind clinical trial study. Prior to the study, patients were randomly assigned into four groups to receive M. spicata or M. × piperita. Statistical analysis included the χ2 test, relative risk, and Student’s t-test. Fifty courses were analysed for each group that met our eligibility criteria. The treatment and placebo groups applied essential oils of M. spicata, M. × piperita, or a placebo, while the control group continued with their previous antiemetic regimen. Patients or guardians recorded the number of emetic events, the intensity of nausea over 20 h of chemotherapy, as well as any possible adverse effects that occurred during this time.

Results: There was a significant reduction in the intensity and number of emetic events in the first 24 h with M. spicata and M. × piperita in both treatment groups (p < 0.05) when compared with the control and no adverse effects were reported. The cost of treatment was also reduced when essential oils were used.

Conclusion: M. spicata or M. × piperita essential oils are safe and effective for antiemetic treatment in patients, as well as being cost effective.