Background/Objectives: The search for natural alternatives in breast cancer (BC) management has spurred interest in plant-derived extracts, particularly oregano variants and their bioactive compound carvacrol (Cv). However, Mexican oregano (Lippia graveolens) infusion (MoI) remains unexplored. This study aimed to chemically characterize MoI and compare its anticancer effects with Cv across BC cell lines, including aggressive triple-negative (TN) subtypes. Methods: MoI was analyzed for composition, antioxidant capacity (ABTS, DPPH, FRAP, total phenols/flavonoids), and phytochemical profile (FTIR, HPLC). Anticancer activity was assessed via MTT and LDH assays. Results: MoI exhibits strong antioxidant capacity and concentration-dependent antiproliferative effects, with IC50 values ranging from 0.08 to 0.18 mg/mL across BC lines, significantly higher (i.e., less cytotoxic) than Cv IC50 of 121–211 µM. Importantly, MoI displayed markedly lower cytotoxicity toward non-cancerous cells (IC50 0.18 mg/mL) compared to Cv (IC50 110 µM). Conclusions: While both agents reduced metabolic activity, Cv induced a more acute suppression. These findings position MoI as a promising, selective candidate for BC therapy, particularly for poor-prognosis subtypes like TN BC, warranting further mechanistic investigation.

The investigation of alternatives for the management of breast cancer (BC), has led to the study of extracts of plant origin and their compounds, within these, the extracts of oregano variants and carvacrol (Cv) have shown promising results, however, the Mexican oregano (L. graveolens) infusion (MoI) has not been studied, so the aims of this work are; to characterize the plant used, and to compare against Cv, the impact on the metabolism and cytotoxicity of BC cell lines. Within the characterization of the plant, moisture, ash, protein, available carbohydrates, ethereal extraction and dietary fiber were determined, additionally, for the MoI characterization antioxidant capacity analysis; ABTS, DPPH, phenols, flavonoids and Ferric reducing antioxidant power (FRAP) were carried, as well as Fourier-transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) to evaluate the composition of the extract, for anticancer activity 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays (MTT) and lactate dehydrogenase (LDH) were performed. The results demonstrated that MoI possesses potent antioxidant activity and antiproliferative effect against BC cell lines, with lower cytotoxicity on non-cancer cells compared to Cv. However, both the infusion and Cv caused a reduction in cell metabolism, with Cv having the most acute effect. Thus, the present investigation provides evidence on the efficacy of these alternative treatments in BC cell lines, including aggressive subtypes such as triple negative (TN).