Supplements and Co-codamol.
Co-codamol, sold under the brand names Solpadol, Tylex, Kapake, Zapain, Emcozin, is a combination opioid analgesic.
Co-codamol is a combination opioid analgesic. In UK prescribing that mostly means codeine combined with paracetamol, or dihydrocodeine combined with paracetamol. The combination places a weak opioid alongside paracetamol, allowing lower doses of each component for additive analgesia. The supplement surface combines the opioid concerns with the paracetamol concerns. Opioid side. Additive CNS depression with alcohol, benzodiazepines, kava, valerian at higher doses, magnesium glycinate at high doses at bedtime; serotonergic concerns for combinations containing tramadol. Paracetamol side. Additive hepatotoxicity at chronic high doses, particularly alongside alcohol or supplements with hepatic load. Codeine is a CYP2D6 prodrug requiring conversion to morphine for analgesic effect. CYP2D6 inhibitors (some SSRIs, certain supplements at high doses) reduce that conversion and the analgesic effect. The CYP2D6 ultra metaboliser genotype carries the opposite concern, with excessive morphine production.
Below are the 2 documented pairs we have explicitly assessed against Co-codamol in the Distil database: 1 severe and 1 caution. The pairs cluster around 1 mechanism: Additive serotonergic activity. 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 9 November 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.
Additive serotonergic activity
Severe Does 5-HTP interact with Co-codamol?
5-HTP is turned into serotonin in the body, and co-codamol contains codeine, an opioid whose UK product information warns of serotonin syndrome with serotonergic medicines, so taking the two together can cause serotonin syndrome (agitation, sweating, tremor, a racing heart, confusion). Do not take 5-HTP with co-codamol; if you already take both, tell your GP or pharmacist, and do not stop a prescribed painkiller on your own.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does St John's Wort interact with Co-codamol?
Co-codamol contains codeine, and codeine and St John's Wort can both act on serotonin, so taking them together may raise the risk of serotonin syndrome (agitation, sweating, tremor, shivering, a racing heart, confusion). If you take co-codamol regularly, talk to your prescriber or pharmacist before starting St John's Wort.
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 (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 the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A 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.
£49 until 30 June 2027 · £79 from 1 July 2027.
Something missing?
If a supplement or medication you take isn't in our autocomplete, tell us. What people flag joins the queue of what we add next.