Collagen Precursors and medications.
Collagen Precursors is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
Collagen precursors are a stack rather than a single ingredient: vitamin C around 1,000mg, glycine 3 to 5g, proline 500mg and lysine 500mg. The logic is that these are the raw materials your body uses to build its own collagen, with vitamin C acting as the cofactor for the enzymes that cross-link collagen fibres. The Grade B rating is indirect, resting on the evidence for the individual components rather than trials of the combined stack, so the honest framing is that this is the best available route for vegans and not a like-for-like substitute. Direct collagen supplementation has stronger and more specific evidence. There are no notable drug interactions at these doses, though high vitamin C can loosen stools in some people. If you eat animal products, direct collagen is the more evidence-backed choice. This stack exists because vegan clients have no dietary collagen source at all.
Below are the 3 documented pairs we have explicitly assessed for Collagen Precursors: 3 amber. The pairs cluster around 2 mechanisms: Reduced anticoagulant effect and Reduced immunosuppressant level. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Reduced anticoagulant effect
This collagen precursor blend contains 1,000 mg of vitamin C, a high daily dose. Very high doses of vitamin C have been linked in rare reports to a reduced effect of vitamin-K-based blood thinners like acenocoumarol, which could lower your INR. If you take acenocoumarol, keep this blend steady and mention it to your anticoagulant clinic.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
This collagen precursor blend contains 1,000 mg of vitamin C, which is a high daily dose. There are reports of large daily doses of vitamin C making warfarin work less well, so your INR (the blood test that shows how thinned your blood is) drops below the level you need. In each case the INR came back up once the vitamin C was stopped. If you take warfarin, tell whoever manages it before starting or stopping this blend, so your INR can be watched and kept stable.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Reduced immunosuppressant level
This collagen precursor blend contains 1,000 mg of vitamin C. In transplant patients, high-dose antioxidant vitamins have been linked to a modest fall in ciclosporin blood levels, which matters because ciclosporin needs to stay within a tight range. If you take ciclosporin, do not start this blend without asking your transplant team, who may want to check your ciclosporin levels.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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.
Read the full methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
See a real sample reportSomething missing?
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.