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Class landing · Antibiotics

Supplements and antibiotics.

What to space apart, what is safe, and the few combinations that matter, alongside ciprofloxacin, doxycycline and the macrolides.

Most antibiotic and supplement interactions are about timing, not danger. Quinolones (ciprofloxacin) and tetracyclines (doxycycline) bind to metal ions, so taken at the same time as calcium, iron, magnesium or zinc they form a complex the gut cannot absorb, and both the mineral and the antibiotic lose effect. The answer is spacing: take the mineral at least two hours apart from the antibiotic.

A few combinations are more than timing. Red yeast rice with a macrolide (clarithromycin, erythromycin) is the one to avoid: the macrolide blocks CYP3A4, which raises the lovastatin naturally present in red yeast rice and drives muscle-toxicity risk. St John’s Wort speeds up clearance of some antibiotics that are broken down by the CYP3A4 enzyme, reducing their effect. Melatonin levels tend to rise with ciprofloxacin, and high-dose vitamin A alongside doxycycline may add to a rare raised-pressure effect. Probiotics are generally fine and often helpful, just taken a couple of hours apart.

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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.
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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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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.