Don’t stop proper treatment to try folk remedies or supplements

In observational cancer data, people using alternative treatment instead of conventional treatment had 2.5 times the mortality hazard. People using complementary approaches alongside treatment more often refused surgery, chemotherapy and radiotherapy; the excess mortality was associated with treatment refusal. Some herbs can also weaken transplant or anticoagulant medicines, so discuss supplements with the treating clinician.

No cost at all; you even save money you’d otherwise spend on supplements. It takes no extra time. The hard part is resisting repeated pressure from others to give it a try.

Two US cancer-registry studies concerned nonmetastatic, potentially treatable breast, prostate, lung and colorectal cancers. In the first, patients choosing alternative medicine without conventional surgery, radiation, chemotherapy or hormone therapy had a mortality HR of 2.50 (95% CI 1.88–3.27) versus matched conventionally treated patients. Site-specific HRs were 5.68 (3.22–10.04) for breast cancer, 2.17 (1.42–3.32) for lung cancer and 4.57 (1.66–12.61) for colorectal cancer. The second examined complementary medicine with conventional care: refusal rates were 7.0% versus 0.1% for surgery, 34.1% versus 3.2% for chemotherapy, 53.0% versus 2.3% for radiotherapy and 33.7% versus 2.8% for hormone therapy. Five-year survival was 82.2% versus 86.6%; mortality HR was 2.08 (1.50–2.90). After accounting for delay and refusal, complementary medicine itself had no clear association with mortality: HR 1.39 (0.83–2.33). The authors attributed the excess to refusal of conventional care. China's market regulator requires health-food labels to state that such products are not medicines and cannot replace disease treatment. The US NCCIH notes that St John's wort can weaken drugs including cyclosporine and warfarin.

Grade B: both studies were observational cancer-registry analyses, not randomized comparisons, and people choosing alternatives may differ in other ways. See item 1 for completing prescribed treatment for hypertension, diabetes and other conditions. Tell the treating clinician before trying supplements. See section 6, item 10 for spending on health products and tonics.

Johnson SB, Park HS, Gross CP, Yu JB (2018). Use of Alternative Medicine for Cancer and Its Impact on Survival. Journal of the National Cancer Institute, 110(1), 121-124. https://doi.org/10.1093/jnci/djx145；Johnson SB, Park HS, Gross CP, Yu JB (2018). Complementary Medicine, Refusal of Conventional Cancer Therapy, and Survival Among Patients With Curable Cancers. JAMA Oncology, 4(10), 1375-1381. https://doi.org/10.1001/jamaoncol.2018.2487；国家市场监督管理总局 (2019). 市场监管总局就《保健食品标注警示用语指南》和《保健食品原料目录与保健功能目录管理办法》有关情况举办专题新闻发布会. https://www.samr.gov.cn/tssps/sjdt/tpxw/art/2023/art_4b658b824b1b4b0ba57c09a56cc93aad.html；National Center for Complementary and Integrative Health (2025). St. John's Wort. https://www.nccih.nih.gov/health/st-johns-wort