Supplements and Doxycycline.
Doxycycline, sold under the brand names Vibramycin, Efracea, Doryx, Oracea, is classified under "tetracycline" in the BNF.
Doxycycline is an antibiotic, usually taken as a short course, and the supplement questions people ask most when given one have reassuring answers. Probiotics are fine to take alongside it and lower the chance of antibiotic-related diarrhoea: space a bacterial probiotic, most Lactobacillus or Bifidobacterium products, about two hours from your dose, while Saccharomyces boulardii, which is a yeast, can be taken at the same time. Most everyday vitamins and minerals have no significant interaction with a short antibiotic course, so a daily multivitamin, vitamin D or vitamin C is generally not a concern. The combinations that genuinely matter are listed below with their evidence, and they tend to be specific: supplements that thin the blood, serotonergic supplements stacked on certain antibiotics, and supplements that are really a prescription drug in disguise, such as red yeast rice, which contains the statin lovastatin. One timing rule applies to Doxycycline specifically: calcium, iron, magnesium and zinc bind it in the gut and reduce how well it is absorbed, so separate any of those supplements from your dose by about two hours. The sensible step in every case is to tell your pharmacist what you already take, which is free at any UK community pharmacy.
Below are the 11 documented pairs we have explicitly assessed against Doxycycline in the Distil database: 9 amber and 2 green. The pairs cluster around 4 mechanisms: Absorption interference, Mineral chelation (absorption), Additive raised intracranial pressure, and Probiotic timing with antibiotics. 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 17 June 2026. Each interaction below is assessed against PubMed-indexed evidence.
Absorption interference
Amber Does Psyllium Husk interact with ?
Psyllium is a gel-forming fibre that can hold on to medicines taken at the same time and carry some of the dose through your gut before it is absorbed, which may mean a little less of the antibiotic gets into you. This is a general fibre effect rather than something special about this antibiotic, so take your psyllium at least 2 hours apart from your doxycycline to keep the antibiotic working properly.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Mineral chelation (absorption)
Amber Does Calcium interact with ?
Calcium binds to doxycycline in the gut and can reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any calcium supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Iron interact with ?
Iron binds to doxycycline in the gut and can seriously reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any iron supplement.
Evidence: Supported by human study data.
Amber Does Magnesium interact with ?
Magnesium can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any magnesium supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Magnesium Glycinate interact with ?
Magnesium can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any magnesium supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Magnesium L-Threonate interact with ?
Magnesium can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any magnesium supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Zinc interact with ?
Zinc can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any zinc supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Zinc Bisglycinate interact with ?
Zinc can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any zinc supplement.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive raised intracranial pressure
Amber Does Vitamin A interact with ?
Both vitamin A in excess and tetracycline antibiotics such as doxycycline can raise the pressure of the fluid around the brain, a condition sometimes called benign intracranial hypertension. Taking them together may add to that risk, which can cause a persistent headache and changes in vision. If you are on doxycycline, it is sensible to avoid high-dose vitamin A supplements and to tell your prescriber straight away about any new or worsening headache or visual changes.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Probiotic timing with antibiotics
Green Does Bifidobacterium longum 1714 interact with ?
Bifidobacterium longum 1714 and doxycycline are fine to use together, and the strain may lower the chance of antibiotic-related diarrhoea. Bifidobacterium longum 1714 is a live bacterium, so space it about two hours away from your doxycycline dose so the antibiotic does not reduce the live bacteria. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when any probiotic should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does Probiotics interact with ?
Probiotics and doxycycline are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your doxycycline dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
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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- 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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