The short answer
This guide helps you discuss herbs, ceremonies, healers, diets, and body practices openly so the plan can respect values and reduce interaction risk. It is a planning tool, not an individual medical, legal, or coverage decision.
The main goal is to discuss herbs, ceremonies, healers, diets, and body practices openly so the plan can respect values and reduce interaction risk.
Tell both the oncology team and traditional healer what else you are using.
Bring product labels, ingredients, doses, and schedules.
Ask about interactions, infection, bleeding, liver or kidney effects, and treatment timing.
Choose how you want to understand this
The full explanation.
Two different questions, often muddled together
Traditional healing covers an enormous range. Prayer and ceremony. A healer in the community. Cupping, massage, moxibustion, acupuncture. Herbal teas, powders, and oils. Foods eaten or avoided for reasons that go back generations.
For safety, only one line matters. Does anything enter the body?
A ceremony, a blessing, or a prayer does not interact with chemotherapy. Something you swallow, drink, or rub into the skin might. So sort your practices into those two groups. It is the most useful thing you can do before the next appointment.
Complementary and alternative are not the same word
NCI draws the line carefully, and it carries real consequences.
Complementary medicine is "used along with standard medical treatment but is not considered by itself to be standard treatment." NCI's example is using acupuncture to help lessen some side effects of cancer treatment.
Alternative medicine is "used instead of standard medical treatment." NCI's example is using a special diet to treat cancer instead of a prescribed drug.
Almost everything below turns on which of those two you are doing.
When traditional practice replaces treatment
Here the harm is measurable. It is better said plainly than hinted at.
NCI reported on a study of 281 people with non-metastatic cancer. All of them refused conventional treatment and chose alternative therapies instead. They were compared with matched patients who had conventional treatment.
Over five years, those with breast or colorectal cancer were about five times as likely to die. Those with lung cancer were more than twice as likely to die. For prostate cancer, no survival difference was found.
The lead researcher's conclusion was that there is "an increased risk of death with choosing alternative medicine."
That is not an argument against your beliefs. It is an argument about timing. A tumor that was curable in March may not be curable in September.
When it is used alongside
The picture here is more encouraging, and more interesting.
A 2018 study in JAMA Oncology used data on nearly two million patients. All had non-metastatic breast, prostate, lung, or colorectal cancer. It compared people who used complementary medicine with matched controls.
The complementary medicine group refused conventional treatment far more often. For chemotherapy it was 34.1 percent against 3.2 percent. For radiotherapy it was 53.0 percent against 2.3 percent. Their five-year survival was lower: 82.2 percent against 86.6 percent.
Then the researchers accounted for that treatment refusal. The survival gap stopped being statistically significant. The hazard ratio fell to 1.39, with a confidence interval crossing 1.
Read that twice, because it is the crux. The danger was not in using complementary practices. The danger was in what some people used them to replace.
The interaction problem is real and specific
Herbs are drugs. The body absorbs them, the liver processes them, and the kidneys clear them. Cancer medicines use the same machinery.
NCI explains that the "cytochrome P450 superfamily of enzymes are important for how the body metabolizes many cancer drugs." A protein called P-glycoprotein also pushes substances back out of cells. Herbs that speed up or block these systems change how much drug reaches the tumor.
Documented examples from NCI and NCCIH:
- St John's wort. Patients taking it with anticancer drugs "had lower levels of the drugs in their blood." NCI's conclusion is that "anticancer drugs may be less effective if taken with St. John's wort." NCCIH says it "interacts with many types of drugs." It usually "speeds up the processes that change the drug into inactive substances."
- Grapefruit. It cuts both ways. Less etoposide reached the bloodstream in people who drank grapefruit juice. Levels of imatinib, sunitinib, and nilotinib went up instead.
- Ginseng. One patient developed liver damage while combining ginseng with an anticancer drug, though the cause was not certain. NCCIH also flags a possible interaction with calcium channel blockers and other blood pressure medicines.
- Green tea. One man's symptoms got worse while he drank green tea with an anticancer drug. They improved when he stopped. NCCIH notes that concentrated green tea supplements can lower blood levels of some drugs.
- Goldenseal. NCCIH says it "may change the way your body processes many drugs," including metformin.
NCCIH also warns about drugs with a narrow safety margin, where small changes matter a lot. It names digoxin, cyclosporine, and warfarin.
Antioxidant supplements during chemotherapy and radiation
This one surprises people, because antioxidants are sold as protective.
NCI reports that studies found "an increased risk of death and a reduced chance of staying cancer free when antioxidant dietary supplements were used during chemotherapy and radiation therapy."
Some treatments work partly by causing oxidative damage inside cancer cells. Blunting that may blunt the treatment. Raise this before treatment starts, not halfway through.
The label may not match the contents
Even a well-chosen herb can arrive contaminated. NCCIH reports that some Chinese herbal products have been found to contain:
- undeclared plant or animal material.
- drugs, including the blood thinner warfarin and the anti-inflammatory diclofenac.
- heavy metals such as arsenic, lead, and cadmium.
- pesticides, or compounds called sulfites.
NCCIH also notes manufacturing errors. One herb has been substituted for another, and organ damage has followed.
This is not a comment on traditional systems of medicine. It is a comment on the supply chain. A preparation made by a healer you know, from plants you can name, is a different risk from a capsule bought online from an unknown maker.
Practices that touch or break the skin
NCCIH reports that "relatively few complications from using acupuncture have been reported." That is reassuring, with one condition attached: it has to be done properly.
Poorly delivered acupuncture "can cause serious adverse effects, including infections, punctured organs, collapsed lungs, and injury to the central nervous system." Non-sterile needles have caused harm.
If you are on cancer treatment, ask the oncology team about anything that breaks the skin or presses hard on tissue. Ask about timing around low blood counts. Ask about cupping, scraping, deep massage, and needling near a surgical site, a port, or an arm with lymphedema.
How to raise it without being lectured
Many people say nothing because they expect to be dismissed. That silence is the real danger. It hides the interactions.
NCI's instruction is blunt: "tell your doctor if you're taking any dietary supplements, even vitamins, no matter how safe you think they are."
A sentence that works: "I use these things and I plan to keep using them. I want to know which ones could interfere with my treatment."
That puts the pharmacist to work on the real question. It does not start an argument about worldview. If a clinician brushes you off, ask for the oncology pharmacist by name. Checking drug interactions is their actual job.
What to bring
- The container itself, not a photo, and not the name from memory.
- The ingredient list, including anything written in another language.
- How much you take, and how often.
- Who prepared it, and where it came from.
- Anything you have stopped, and when you stopped it.
Bring this list before each new treatment starts, not only at the first visit. Cancer regimens change. An herb that was harmless with one drug may not be with the next.
When to get help sooner
- Call 911 or go to an emergency department if a preparation is followed by swelling of the lips, tongue or throat, a spreading hives rash, wheezing, or trouble breathing. NCCIH notes that some Chinese herbal products have carried sulfites, which can set off asthma or a severe allergic reaction.
- Call 911 or go to an emergency department if sharp chest pain or sudden breathlessness starts after needling, cupping or scraping over the chest or upper back. A punctured organ and a collapsed lung are among the complications NCCIH links to acupuncture that is not done properly.
- Call your care team the same day if your skin or the whites of your eyes turn yellow, your urine goes dark, or you get pain under the right ribs while taking any herb or supplement. Wrong or substituted herbs have caused organ damage, and one report describes liver damage in a patient combining ginseng with an anticancer drug.
- Call your care team the same day if a needling, cupping or scraping site turns red, hot, swollen or leaky, or you spike a temperature of 100.4°F (38°C) or higher afterwards. Infection is the complication most often reported with non-sterile needles. But if you are receiving chemotherapy, that same temperature is an emergency rather than a phone call — your blood counts may be at their lowest, and emergency departments are set up to give antibiotics quickly.
- Call your care team the same day if you start bruising easily, bleeding from the gums or nose, or find blood in your urine or stool. Some products have been found to contain undeclared warfarin, a blood thinner.
- Call your care team within a day or two if you realise a product you take may interact with your treatment, or you have stopped one abruptly. Ask for the oncology pharmacist. Bring the container.
Sources
- Complementary and Alternative Medicine — National Cancer Institute
- Cancer Therapy Interactions With Foods and Dietary Supplements (PDQ) — Patient Version — National Cancer Institute
- Alternative Medicine for Cancer Treatment Raises Mortality Risk — National Cancer Institute
- Complementary Medicine, Refusal of Conventional Cancer Therapy, and Survival Among Patients With Curable Cancers — JAMA Oncology, on PubMed
- 6 Tips: How Herbs Can Interact With Medicines — National Center for Complementary and Integrative Health
- Traditional Chinese Medicine: What You Need To Know — National Center for Complementary and Integrative Health
- Acupuncture: Effectiveness and Safety — National Center for Complementary and Integrative Health
- Infection and Neutropenia during Cancer Treatment — National Cancer Institute
- Fever and Cancer Treatment — Centers for Disease Control and Prevention
Words to know
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Common questions
Do I have to give up traditional practices to have cancer treatment?
For safety, only one line matters: does anything enter the body? A ceremony, a blessing or a prayer does not interact with chemotherapy. Something you swallow, drink or rub into the skin might. Sorting your practices into those two groups is the most useful thing to do before your next appointment.
Is using complementary medicine alongside treatment dangerous?
A 2018 JAMA Oncology study of nearly two million patients found lower five-year survival in the complementary medicine group, 82.2 percent against 86.6 percent. But that group also refused conventional treatment far more often, 34.1 percent against 3.2 percent for chemotherapy. Once treatment refusal was accounted for, the survival gap stopped being statistically significant. The danger was in what some people used these practices to replace.
What happens if I use traditional healing instead of treatment?
NCI reported on 281 people with non-metastatic cancer who refused conventional treatment and chose alternative therapies. Over five years, those with breast or colorectal cancer were about five times as likely to die, and those with lung cancer more than twice as likely. For prostate cancer, no survival difference was found. The issue is timing: a tumor that was curable in March may not be curable in September.
Which herbs and foods are known to interfere with cancer drugs?
St John's wort lowered blood levels of anticancer drugs, which may make them less effective. Grapefruit cuts both ways: less etoposide reached the bloodstream, while imatinib, sunitinib and nilotinib levels went up. Goldenseal may change the way the body processes many drugs, and concentrated green tea supplements can lower blood levels of some drugs.
How do I raise this without being lectured?
Say it as a safety question rather than a debate about worldview. NCI's instruction is blunt: tell your doctor if you are taking any dietary supplement, even vitamins, no matter how safe you think it is. A sentence that works is that you use these things, you plan to keep using them, and you want to know which ones could interfere with treatment. If a clinician brushes you off, ask for the oncology pharmacist by name.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
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Your next step
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Sources last checked: 2026-08-13 what this meansLast updated: 2026-08-13Next planned review: 2027-07-22
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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