Background: Cancer therapy necessitates innovative approaches with enhanced efficacy and reduced side effects. Essential oils have gained attention because of their diverse biological properties and relatively low toxicity. Zataria multiflora essential oil (ZEO) and Oliveria decumbens essential oil (OEO) exhibit promising anti-cancer effects, particularly in modifying oxidative stress and inflammation. Both oils boast complex compositions rich in bioactive compounds, including oxygenated monoterpenes and phenolic compounds like carvacrol and thymol. Hence, this study investigates essential oils’ anti-cancer, anti-oxidant and immunomodulatory effects, focusing on ZEO and OEO.
Materials and Methods: This review briefly considers the intricate mechanisms of several essential oils, encompassing anti-oxidant, anti-inflammatory and anti-cancer properties. Then the review delves into the multifaceted mechanisms underlying the anti-cancer properties of ZEO and OEO. 
Results: Studies showcase the ability of ZEO and OEO to induce apoptosis in cancer cells through various pathways, such as mitochondrial dysfunction, reactive oxygen species (ROS) generation and DNA damage while sparing normal cells. Our studies further validated the immunomodulatory effects of OEO and ZEO in tumor-bearing mice, resulting in reduced tumor volume. Additionally, this review confirmed the synergistic effect of ZEO when combined with doxorubicin to inhibit cancer cells. 
Conclusion: Some essential oils, such as ZEO and OEO, present promising natural compounds in cancer therapy, offering diverse mechanisms of action targeting various aspects of tumor biology.