Medication · cytotoxic

Supplements and Colchicine.

Every documented pair, every citation. Below: 1 documented pair grouped by mechanism.

Colchicine is a cytotoxic agent.

Colchicine is a cytotoxic agent. The class is heterogeneous (alkylators, antimetabolites, anthracyclines, taxanes, platinums) and the supplement profile depends sharply on the specific agent. Two patterns sit at the top of clinical concern. First, antioxidant supplements at high dose (vitamin C IV, vitamin E, NAC, glutathione) carry a theoretical concern about blunting the reactive oxygen species damage that chemotherapy causes in tumour cells. The oncology trial evidence is mixed. Most UK centres advise against high antioxidant doses during active treatment. Second, CYP3A4 and P-glycoprotein interactions matter for the orally dosed cytotoxics (capecitabine, imatinib, sunitinib and the kinase inhibitor family). The supplements that hit transplant medicines (curcumin, quercetin, St John's Wort) carry the same plasma level concern here. The oncology pharmacist, not the GP or community pharmacist, is the gatekeeper for any new supplement during active cytotoxic therapy.

Below are the 1 documented pair we have explicitly assessed against Colchicine in the Distil database: 1 amber. The pairs cluster around 1 mechanism: Absorption interference. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.

Documented interactions

Absorption interference

Amber Vitamin B12

Long-term colchicine can reduce how well your gut absorbs vitamin B12. It does this by temporarily damaging the lining of the lower small intestine, where B12 is taken up. The effect is linked to higher doses and longer courses, and it reverses once colchicine is stopped. Short courses for a gout flare are not a concern. If you are on colchicine long term, it is worth asking your GP about a B12 blood test.

PMID 5677718 · PMID 5416781 · PMID 759260 · BNF: Colchicine

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

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If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.