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Over-The-Counter Medications

Why Consider Taking over-the-counter (OTC) Medications?

A growing body of clinical and observational research suggests that select OTC and repurposed medications may enhance the effectiveness of cancer treatments without substantially increasing risk. Many of these agents, such as melatonin, aspirin, metformin, and probiotics, are widely available, inexpensive, and have been associated with meaningful reductions in cancer-specific mortality or improved treatment response when used alongside standard therapies. While not a substitute for conventional care, these compounds may offer a low-cost, low-risk way to support treatment outcomes, especially when used under medical guidance and tailored to each patient’s treatment plan.

Key Lifestyle Insights

  • Metformin – A diabetes drug that may reduce cancer-specific mortality by 34% (HR: 0.66) by lowering blood sugar and inhibiting tumor growth pathways (1).
  • Melatonin – A sleep aid that may enhance immune function and improve treatment response when used alongside chemotherapy or radiation (2).
  • NSAIDs – Common pain relievers like aspirin may lower cancer mortality by 21% (HR: 0.79) through anti-inflammatory and COX-inhibiting effects (3).
  • Probiotics – Gut-supporting bacteria that may improve survival (HR: 0.55) and treatment tolerance by enhancing immune response and reducing toxicity (4).
  • Quercetin – A plant flavonoid that may slow cancer spread by promoting apoptosis and disrupting tumor cell signaling, with promising early data (5).
  • Berberine – A compound used for metabolic conditions that may suppress tumor growth by altering metabolism and the cell cycle (6).
  • Curcumin – A turmeric-derived supplement that may reduce tumor burden and inflammation, with meta-analyses showing survival and quality-of-life benefits (7).
  • Propranolol – A beta-blocker linked to improved survival (HR: 0.62) in some cancers by blocking stress-related tumor-promoting pathways (8).
  • Rapamycin – An mTOR inhibitor that may stabilize tumors by slowing cell growth and inducing autophagy in early-stage cancer trials (9).
  • SERMs – Estrogen-blocking drugs like tamoxifen that reduce recurrence and lower breast cancer mortality by about 31% in ER-positive patients (HR: 0.69) (10).
  • Antibiotics – These can impair immunotherapy by disrupting the gut microbiome, leading to worse survival and lower response rates (11).
  • Calcium and Magnesium Antacids – These antacids may reduce the absorption and efficacy of oral cancer drugs like TKIs (12).
  • Cimetidine (Tagamet) – An OTC antacid that may raise chemotherapy toxicity by inhibiting CYP enzymes that metabolize cancer drugs (13).

Discover the Impacts of Different OTC Medications

Discover the Impacts of Different OTC Medications

Many studies suggest that common and repurposed medications may help improve treatment results for a range of cancers. These agents, many of which are accessible without a prescription or are well-established generic drugs, have shown promise in reducing cancer-specific mortality and enhancing therapeutic efficacy. For instance, NSAIDs such as aspirin have been associated with a significant reduction in cancer-related deaths, particularly through anti-inflammatory and anti-platelet mechanisms (14). Melatonin, available as an OTC sleep aid, has demonstrated synergistic effects with chemotherapy, improving one-year survival rates by up to 34% in cancer patients (15). Metformin, though technically a prescription drug for diabetes, is frequently cited in observational studies for its 34% reduction in cancer-specific mortality (16). These findings suggest that inexpensive, widely available agents may serve as valuable adjuncts to standard oncologic care when appropriately integrated.

Other OTC supplements and repurposed drugs are also being actively explored for their anticancer effects. Curcumin, a compound in turmeric, has been shown to suppress tumor growth and modulate multiple cell signaling pathways involved in cancer progression (17). Similarly, quercetin, a flavonoid found in many dietary supplements, exhibits pro-apoptotic and anti-proliferative effects in various tumor models (18). Probiotics have gained attention for their role in modulating the gut microbiome, which can influence immune responses and treatment tolerance (19). Berberine, a plant-derived alkaloid, inhibits cancer cell proliferation and angiogenesis in both preclinical and early human studies (20). Propranolol, a beta-blocker, has been associated with improved cancer survival through stress-axis modulation (21). Rapamycin and related mTOR inhibitors are being evaluated for their role in reducing cancer cell growth via autophagy and metabolic regulation (22). Lastly, selective estrogen receptor modulators (SERMs) such as tamoxifen, while prescription-based, are long-standing therapies with proven survival benefits in hormone-sensitive cancers and are under investigation for broader anticancer utility (23). Collectively, these agents underscore the potential of accessible, safe, and low-cost medications in enhancing cancer treatment outcomes across tumor types.

  1. Nie, J., Zhao, C., Deng, L. I., Chen, Y., Li, Y., & Yang, H. (2021). Metformin therapy and risk of cancer: A meta-analysis. Cancer Prevention Research, 14(9), 709–720. https://doi.org/10.1158/1940-6207.CAPR-20-0495
  2. Wang, Y., Liu, D., Zheng, Q., Li, W., Wang, S., & Wang, Y. (2012). Effects of melatonin in combined chemotherapy for cancer patients: A systematic review and meta-analysis. PLOS ONE, 7(6), e34572. https://doi.org/10.1371/journal.pone.0034572
  3. Rothwell, P. M., Fowkes, F. G., Belch, J. F., Ogawa, H., Warlow, C. P., & Meade, T. W. (2011). Effect of daily aspirin on long-term risk of death due to cancer: Analysis of individual patient data from randomized trials. Lancet, 377(9759), 31–41. https://doi.org/10.1016/S0140-6736(10)62110-1
  4. Gao, K., Wang, C., Liu, L., Dou, X., Liu, J., Yuan, L., & Li, Y. (2021). Probiotics in cancer treatment: Friend or foe? Frontiers in Microbiology, 12, 660448. https://doi.org/10.3389/fmicb.2021.660448
  5. Tang, S. M., Deng, X. T., Zhou, J., Li, Q. P., Ge, X. X., & Miao, L. (2020). Pharmacological basis and new insights of quercetin action in respect to its anti-cancer effects. Biomedicine & Pharmacotherapy, 121, 109604. https://doi.org/10.1016/j.biopha.2019.109604
  6. Zhang, Q., Xiao, X., Li, M., Li, W., Yu, M., Zhang, H., … & Wang, Y. (2020). Berberine moderates glucose metabolism through the induction of autophagy in hepatocellular carcinoma. Frontiers in Pharmacology, 11, 588349. https://doi.org/10.3389/fphar.2020.588349
  7. Hewlings, S. J., & Kalman, D. S. (2017). Curcumin: A review of its effects on human health. Foods, 6(10), 92. https://doi.org/10.3390/foods6100092
  8. Pasquier, E., Ciccolini, J., Carre, M., Bouclier, C., Boubekeur, M., & André, N. (2016). Propranolol potentiates the anti-angiogenic effects and anti-tumor efficacy of chemotherapy. Angiogenesis, 19(4), 395–407. https://doi.org/10.1007/s10456-016-9510-5
  9. Saxton, R. A., & Sabatini, D. M. (2017). mTOR signaling in growth, metabolism, and disease. Cell, 168(6), 960–976. https://doi.org/10.1016/j.cell.2017.02.004
  10. Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). (2011). Relevance of breast cancer hormone receptors and other factors to the efficacy of adjuvant tamoxifen: Patient-level meta-analysis of randomised trials. Lancet, 378(9793), 771–784. https://doi.org/10.1016/S0140-6736(11)60993-8
  1. Pinato, D. J., Howlett, S., Ottaviani, D., Urus, H., Patel, A., Mineo, T., … & Sharma-Oates, A. (2019). Association of prior antibiotic treatment with survival and response to immune checkpoint inhibitor therapy in patients with cancer. JAMA Oncology, 5(12), 1774–1778. https://doi.org/10.1001/jamaoncol.2019.2785
  2. Spina, E., & Scordo, M. G. (2002). Clinically significant drug interactions with atypical antipsychotics: An update. Clinical Pharmacokinetics, 41(12), 949–970. https://doi.org/10.2165/00003088-200241120-00002
  3. Budha, N. R., Frymoyer, A., Smelick, G. S., Jin, J. Y., Yago, M. R., Dresser, M. J., & Holden, S. N. (2012). Drug absorption interactions between oral targeted anticancer agents and PPIs: Is pH-dependent solubility the Achilles heel of targeted therapy? Clinical Pharmacology & Therapeutics, 92(2), 203–213. https://doi.org/10.1038/clpt.2012.61
  4. Rothwell, P. M., Fowkes, F. G., Belch, J. F., Ogawa, H., Warlow, C. P., & Meade, T. W. (2011). Effect of daily aspirin on long-term risk of death due to cancer: Analysis of individual patient data from randomized trials. Lancet, 377(9759), 31–41. https://doi.org/10.1016/S0140-6736(10)62110-1
  5. Wang, Y., Liu, D., Zheng, Q., Li, W., Wang, S., & Wang, Y. (2012). Effects of melatonin in combined chemotherapy for cancer patients: A systematic review and meta-analysis. PLOS ONE, 7(6), e34572. https://doi.org/10.1371/journal.pone.0034572
  6. Nie, J., Zhao, C., Deng, L. I., Chen, Y., Li, Y., & Yang, H. (2021). Metformin therapy and risk of cancer: A meta-analysis. Cancer Prevention Research, 14(9), 709–720. https://doi.org/10.1158/1940-6207.CAPR-20-0495
  7. Hewlings, S. J., & Kalman, D. S. (2017). Curcumin: A review of its effects on human health. Foods, 6(10), 92. https://doi.org/10.3390/foods6100092
  8. Tang, S. M., Deng, X. T., Zhou, J., Li, Q. P., Ge, X. X., & Miao, L. (2020). Pharmacological basis and new insights of quercetin action in respect to its anti-cancer effects. Biomedicine & Pharmacotherapy, 121, 109604. https://doi.org/10.1016/j.biopha.2019.109604
  9. Gao, K., Wang, C., Liu, L., Dou, X., Liu, J., Yuan, L., & Li, Y. (2021). Probiotics in cancer treatment: Friend or foe? Frontiers in Microbiology, 12, 660448. https://doi.org/10.3389/fmicb.2021.660448
  10. Zhang, Q., Xiao, X., Li, M., Li, W., Yu, M., Zhang, H., … & Wang, Y. (2020). Berberine moderates glucose metabolism through the induction of autophagy in hepatocellular carcinoma. Frontiers in Pharmacology, 11, 588349. https://doi.org/10.3389/fphar.2020.588349
  11. Pasquier, E., Ciccolini, J., Carre, M., Bouclier, C., Boubekeur, M., & André, N. (2016). Propranolol potentiates the anti-angiogenic effects and anti-tumor efficacy of chemotherapy. Angiogenesis, 19(4), 395–407. https://doi.org/10.1007/s10456-016-9510-5
  12. Saxton, R. A., & Sabatini, D. M. (2017). mTOR signaling in growth, metabolism, and disease. Cell, 168(6), 960–976. https://doi.org/10.1016/j.cell.2017.02.004
  13. Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). (2011). Relevance of breast cancer hormone receptors and other factors to the efficacy of adjuvant tamoxifen: Patient-level meta-analysis of randomised trials. Lancet, 378(9793), 771–784. https://doi.org/10.1016/S0140-6736(11)60993-8

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