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Class landing · Contraceptives

Supplements and oral contraceptives.

The combined pill, progestogen-only pill, and the supplements that reduce contraceptive reliability.

Oral contraceptives carry one unambiguous supplement red flag and several smaller patterns. The red flag is St John’s Wort: it induces CYP3A4 and accelerates clearance of ethinyl oestradiol and most progestogens. Three randomised controlled trials (Pfrunder 2003, Hall 2003, Murphy 2005) document the effect, and documented contraceptive failures have followed. This is a hard exclusion on combined and progestogen-only pills.

Beyond that, long-term combined-pill use is associated with lower levels of folate, B6, B12, vitamin C, zinc and selenium on group-level studies. A standard multivitamin covers the gap. The class page above pre-selects the three most-prescribed UK combined and progestogen-only pills; add the supplements you take and check.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP or pharmacist, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.
Add every supplement you take. Type a name and click each match to add it, as many as you like.
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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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The full report

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.

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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.