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Free Drug-Supplement Interaction Checker

Check if your supplements are safe with your medications — 1,823 interaction rules based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature. Instant results. No account needed. Used by people managing complex medication and supplement stacks.

1,823 interaction rules
Published sources
Free forever
30 sec results
No account needed
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Free · No account · Not medical advice

Example interaction results

EXAMPLE — WARFARIN + FISH OIL + VITAMIN K2
Fish Oil + Warfarin — High Severity
Fish oil enhances Warfarin blood thinning. Monitor INR closely. Notify your prescriber before combining.
Vitamin K2 + Warfarin — Moderate
Vitamin K2 affects INR. Keep dose consistent and monitor with your anticoagulation clinic.
Fish Oil + Vitamin D3 — Beneficial
Omega-3 enhances Vitamin D3 absorption. Taking together improves efficacy of both.
Check YOUR medications and supplements

What Elthio checks

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Drug interactions
1,823 rules covering Warfarin, Levothyroxine, Metformin, statins, SSRIs, GLP-1 agonists, and 50+ more drug classes
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Quality grade A-D
Bioavailability-based grading — know if you are wasting money on poorly absorbed supplement forms
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NIH verification
Cross-references the NIH Dietary Supplement Label Database — 207,000+ registered products
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Timing schedule
When to take each supplement and why — based on NIH absorption science

Who needs this tool

  • People on blood thinners — Warfarin, Eliquis, Xarelto
  • Thyroid patients on Levothyroxine
  • Diabetes patients on Metformin or GLP-1 medications
  • People on statins — Atorvastatin, Simvastatin, Rosuvastatin
  • Anyone taking 3 or more supplements daily
  • Caregivers managing medications for family members
  • GLP-1 users on Ozempic, Wegovy, or Mounjaro

Why drug-supplement interactions matter

An estimated 34% of adults in the US take prescription medications and dietary supplements simultaneously, according to the NIH Office of Dietary Supplements. Many of these combinations have clinically significant interactions that neither the prescribing doctor nor the patient is aware of.

Common examples include fish oil enhancing the blood thinning effect of Warfarin, calcium blocking Levothyroxine absorption by up to 40%, and St. John's Wort reducing the effectiveness of many medications by accelerating liver enzyme activity.

Elthio's database covers 1,823 of these interactions, compiled from federal databases based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature, and organized by severity so the most important warnings appear first.

Frequently asked questions

Is Elthio really free?
Yes — completely free. No account required, no credit card, no paywall. Enter your medications and supplements and get results instantly.
Where does the interaction data come from?
1,823 rules curated from NIH Office of Dietary Supplements, FDA Adverse Event Reporting System (FAERS), NCCIH Herb-Drug Interactions database, and peer-reviewed PubMed literature. See sources below.
Is this a substitute for my pharmacist?
No. Elthio is an educational tool that helps you understand potential interactions before speaking with your healthcare provider. Always confirm with your pharmacist or doctor before making any changes.
Which medications does it cover?
Warfarin, Levothyroxine, Metformin, Atorvastatin, Sertraline, Lisinopril, Amlodipine, Metoprolol, Omeprazole, Gabapentin, Semaglutide, Ozempic, Prednisone, and 50+ more drug classes covering over 200 individual medications.
Does it work on mobile?
Yes — works on any device in the browser. Also available as an Android app on Google Play for offline access and push notifications.
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ABOUT THIS TOOL
Built by Elthio Health
Elthio's interaction database is compiled from NIH Office of Dietary Supplements, FDA Adverse Event Reporting System, and NCCIH herb-drug interaction data. Content is reviewed periodically for clinical accuracy. How we grade
Educational tool only — not medical advice. About · Privacy · Terms

Data sources

Check your supplement stack now

Free · 30 seconds · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature

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Powered by Elthio Health · elthio.health
Based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature; and NIH DSLD data
Educational only — not medical advice.
Always confirm with your doctor or pharmacist before making changes.