Supplements and Co-careldopa (Carbidopa/levodopa).
Co-careldopa (Carbidopa/levodopa), sold under the brand names Sinemet, Caramet, Stalevo, Lecado, is used in Parkinson disease to modulate dopaminergic signalling.
Co-careldopa (Carbidopa/levodopa) is used in Parkinson disease to modulate dopaminergic signalling. The class includes levodopa (combined with carbidopa or benserazide to prevent peripheral conversion), dopamine agonists (ropinirole, pramipexole, rotigotine), MAO-B inhibitors (covered separately), COMT inhibitors, and amantadine. UK prescribing is overseen by neurology specialists. The supplement surface includes two specific timing rules. First, the protein and levodopa absorption rule. Large protein loads compete with levodopa for the same gut amino acid transporter, and need a 30 to 45 minute separation. Second, the iron and levodopa chelation rule. Iron supplements bind levodopa in the gut, reducing absorption and requiring strict separation. Vitamin B6 at high doses historically opposed levodopa monotherapy, but with carbidopa or benserazide given alongside this is no longer an issue at standard supplement doses. 5-HTP and St John's Wort warrant care, given serotonergic and MAO concerns.
Below are the 4 documented pairs we have explicitly assessed against Co-careldopa (Carbidopa/levodopa) in the Distil database: 3 amber and 1 green. The pairs cluster around 4 mechanisms: Mineral chelation (absorption), Dopaminergic potentiation (levodopa-sparing), Levodopa amino-acid transport competition, and Levodopa decarboxylation (B6, neutralised by carbidopa/benserazide). 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
Last reviewed 15 June 2026. Each interaction below is assessed against PubMed-indexed evidence.
Mineral chelation (absorption)
Amber Does Iron interact with ?
Iron binds levodopa and carbidopa in the gut and reduces how much of each you absorb, which can weaken your Parkinson's symptom control. Take your co-careldopa dose and any iron supplement at least two hours apart. Only take iron if a blood test has confirmed your ferritin is low, as Distil does not recommend iron without confirmed deficiency.
Evidence: Supported by human study data.
Dopaminergic potentiation (levodopa-sparing)
Amber Does Citicoline interact with ?
Citicoline raises dopamine activity in the brain, and in Parkinson's studies it has let people get the same control of symptoms on a lower dose of levodopa, in some cases up to half. This is generally a helpful effect rather than a dangerous one, but it is still an interaction: do not adjust your levodopa dose yourself. If you want to try citicoline, raise it with your Parkinson's team so any change in your levodopa dose is planned and supervised.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Levodopa amino-acid transport competition
Amber Does L-Tyrosine interact with ?
Taking an L-Tyrosine supplement around the same time as co-careldopa (Sinemet, which contains levodopa) may blunt how well the medication works, because tyrosine and levodopa are both large amino acids that share the same carrier from the gut into the blood and into the brain. Separate any tyrosine supplement from your doses and discuss it with your Parkinson's team rather than adding it on your own.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Levodopa decarboxylation (B6, neutralised by carbidopa/benserazide)
Green Does Vitamin B Complex interact with ?
There is an old warning that vitamin B6 cancels out levodopa. That warning applies to plain levodopa. Co-careldopa combines levodopa with carbidopa, which blocks the part of the body where B6 would interfere, so B6 in a B complex does not undo co-careldopa the way it can undo levodopa given on its own. This combination is fine. It is still worth keeping your supplement routine steady and mentioning a high-dose B6 product to your Parkinson's team.
Evidence: Supported by human study data.
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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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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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-graded compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 founder pricing while we earn our first reviews. The interactions check is one section of it, and you can read a real one in full before you decide.
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