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. We do not recommend this stack for skin or for joints. The honest position is that no trial of the stack exists, so there is nothing to rank it against. The Grade B rating was never an outcome grade; it was an inference from what the blend contains, and our own database has already watched that kind of inference fail, when a dose of collagen peptides supplying two to three grams of glycine did not reproduce the effect that free glycine has on sleep. Direct collagen supplementation has stronger and more specific evidence. The four ingredients here remain in our database individually, each on whatever evidence it carries in its own right. The 1,000mg of vitamin C in this stack is the part that interacts. At that dose it may reduce the effect of the blood thinners warfarin and acenocoumarol, so keep the blend steady and tell your anticoagulant clinic, and it warrants a word with your transplant team if you take ciclosporin. High vitamin C can also 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, and it is offered on that basis rather than on evidence that it works for skin or joints.
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
Last reviewed 15 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Reduced anticoagulant effect
Amber Does Collagen Precursors interact with Acenocoumarol?
The 1,000 mg of vitamin C in this collagen precursor blend (a high daily dose) may reduce the effect of warfarin-type blood thinners like acenocoumarol, which could lower your INR; very high doses of vitamin C have been linked to this in rare reports. If you take acenocoumarol, keep this blend steady and mention it to your anticoagulant clinic.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Collagen Precursors interact with Warfarin sodium?
The 1,000 mg of vitamin C in this collagen precursor blend (a high daily dose) may make warfarin work less well, so your INR (the blood test that shows how thinned your blood is) drops below the level you need. There are reports of large daily doses of vitamin C doing this, with the INR coming 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.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Reduced immunosuppressant level
Amber Does Collagen Precursors interact with Ciclosporin?
The 1,000 mg of vitamin C in this collagen precursor blend may cause a modest fall in ciclosporin blood levels, which matters because ciclosporin needs to stay within a tight range; in transplant patients, high-dose antioxidant vitamins have been linked to this. If you take ciclosporin, do not start this blend without asking your transplant team, who may want to check your ciclosporin levels.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
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.
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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 methodologyA full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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