Distil ← Back to home
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.

Related guides

Loading database stats…
For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.
Type the supplement name. Click each match to add it.
Brand or generic name works. Click each match to add it.
Anything we should know? (optional)
Pick any that apply. We adjust the findings where context changes the answer.
Add at least one supplement and one medication to check.
Not sure where to start? Try one:
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.

Read the full methodology
Your whole stack

Want 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 report
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.