Antioxidant supplements sit in genuine tension with treatments that are designed to generate oxidative damage, and several supplements touch the enzymes and transporters that clear cancer drugs. Nothing on this page is a reason to stop a cancer treatment; every entry is a reason to hand your oncology team the bottle before you start.
Below is every interaction Magellan documents for this class — 9 entries across 9 supplements, each with the mechanism as the cited reference states it, how serious that reference treats it, and where to take the question next.
Magellan’s Medication Safety Check runs entirely on your device — type the medicines you take and it flags every documented interaction in this dataset. Nothing you type is sent anywhere.
Open the Medication Safety Check →NCCIH states CoQ10 may not be compatible with some types of cancer treatment, so people undergoing chemotherapy should discuss use with their oncology team before taking it.
NCCIH advises that antioxidant supplements may reduce the effectiveness of cancer treatments that work by generating reactive oxygen species, and recommends checking with the oncology care team before use; quercetin is a potent dietary antioxidant/flavonoid, so this general antioxidant-supplement caution is relevant.
Hesperidin may inhibit P-glycoprotein drug transporters, potentially increasing absorption and blood levels of medications that are P-gp substrates.
In clinical trials, acetyl-L-carnitine actually worsened chemotherapy-induced peripheral neuropathy, with the adverse effect persisting at 2-year follow-up; it is not recommended for patients undergoing chemotherapy for neuropathy prevention.
Folate is a methotrexate antagonist; when methotrexate is used for cancer, folate supplements could interfere with its anticancer effect and should only be used under oncologist guidance (when methotrexate is used at low doses for rheumatoid arthritis or psoriasis, folate is sometimes co-prescribed, so the clinical impact depends on the indication).
Because some chemotherapy drugs work by generating free radicals to kill cancer cells, high-dose antioxidants like NAC could theoretically blunt their effectiveness; oncologist consultation is advised before use during active cancer treatment.
People with severe illness or compromised immune systems, and critically ill hospitalized patients, are at greater risk of harmful effects from probiotics, including documented cases of severe or fatal infections; the FDA has specifically warned about this risk in premature infants given probiotics.
High-dose vitamin C can interfere with the activity of several chemotherapy agents by counteracting their oxidative mechanism; patients on active cancer treatment should consult their oncologist before use.
Quercetin-type flavonoids have been shown to substantially increase tamoxifen bioavailability in preclinical studies, and resveratrol-type stilbenes have estrogen-receptor-activating properties; patients on hormone therapy or with hormone-sensitive cancers should discuss use with their oncologist.
Medicines in this group include: Methotrexate (Trexall, Otrexup), Tamoxifen (Nolvadex), Cisplatin, Doxorubicin (Adriamycin), Vincristine (Oncovin), Bortezomib (Velcade), Cyclophosphamide (Cytoxan).
Brand names are listed in brackets after the generic ingredient. If the name on your bottle is not here, the generic name on the label almost always is — and the Medication Safety Check accepts either.
These are the warning signs that go with the medication classes on this page. They are general safety-netting, not a prediction that any supplement will cause them.
If something feels seriously wrong, do not wait for an appointment. Call 911 (US) or your local emergency number.
Severity describes the interaction as the cited reference frames it, not how a specific person will react. A “minor” entry in someone with kidney disease, on five other drugs, can matter more than a “major” one in someone on nothing else.
This is a curated set of interactions with citations — not an exhaustive pharmacology database. An interaction that is absent here has not been ruled out; it may simply not be documented in the references Magellan curates from. Supplements are also not batch-tested for identity or contamination the way prescription drugs are, so what is on the label is a claim rather than a guarantee. And most of these entries come from case reports and mechanistic work rather than randomized trials, which is exactly why the sensible response is a pharmacist review rather than either alarm or dismissal.
4 documented interactions in total.
2 documented interactions in total.
3 documented interactions in total.
7 documented interactions in total.
4 documented interactions in total.
3 documented interactions in total.
2 documented interactions in total.
8 documented interactions in total.
3 documented interactions in total.
Blood thinners · Blood pressure medications · Diabetes medications · Statins · Antibiotics · Immunosuppressants · Diuretics · Other drug classes
Back to the full supplement–drug safety hub → · The evidence-graded supplement guide →
CoQ10 / ubiquinol, Quercetin, Hesperidin (citrus flavonoid), Carnitine (L-carnitine and acetyl-L-carnitine), L-methylfolate (5-MTHF), NAC and GlyNAC, Probiotics, NOVOS Core (multi-ingredient formula), DaVinci Labs Phyto Benefits — 9 documented entries in total (1 major, 7 moderate, 1 minor). Each entry on this page names the reference it came from.
In this dataset the class includes Methotrexate, Tamoxifen, Cisplatin, Doxorubicin, Vincristine, Bortezomib and others. Brand names are mapped to their generic ingredient inside the Medication Safety Check, so typing the name on your bottle works.
Usually not. Most entries here call for one of three things: separating the doses by a few hours, monitoring a lab value or a home reading for a couple of weeks, or a prescriber-led dose adjustment. The decision belongs to the clinician who manages the prescription — what this page is for is making sure the conversation happens before you start rather than after something goes wrong.