If you take more than one supplement daily, you might be unknowingly creating dangerous interactions. I built a free tool to check — and the research behind it was eye-opening.
The Problem: Nobody Checks Supplement Interactions
Walk into any pharmacy in Latin America and you'll find shelves full of supplements: magnesium, omega-3, iron, vitamin D, turmeric. People buy them based on recommendations from friends, influencers, or quick Google searches.
But here's what most people don't know: some supplements actively fight each other for absorption, while others can combine to create dangerous effects.
A few examples that surprised me:
Calcium + Iron: The Classic Mistake
Calcium inhibits iron absorption by up to 60%. If you're taking both — which millions of people do — you might be wasting your iron supplement entirely. The fix is simple: take them at least 2 hours apart. But nobody tells you this on the label.
Source: Hallberg et al., American Journal of Clinical Nutrition, 1991
Omega-3 + Ginkgo Biloba: Hidden Bleeding Risk
Both have antiplatelet effects. Taking them together significantly increases bleeding risk. If you're also taking aspirin or blood thinners, this combination becomes genuinely dangerous. Surgeons recommend stopping both 2 weeks before any procedure.
Source: Bone & Mills, Principles and Practice of Phytotherapy, 2013
Berberina + Probiotics: One Kills the Other
Berberine has antibacterial properties — which means it can kill the very bacteria you're paying for in your probiotic supplement. Take them at different times of day with at least 2 hours separation.
Source: Zhang et al., Frontiers in Cellular and Infection Microbiology, 2021
What I Built
I created the Supplement Stack Checker — a free, client-side tool where you select the supplements you take and instantly see:
- Dangerous interactions (high severity, color-coded red)
- Absorption competition (where timing matters)
- Beneficial synergies (combinations that actually help each other)
- Optimal timing schedule (when to take each supplement)
The entire tool runs in the browser — no server, no tracking, no accounts. It's a single HTML file with embedded JavaScript.
The Data
Currently covers 44 supplements and 40+ documented interactions, each backed by published clinical research. Every interaction card shows:
- The mechanism (why it happens)
- The recommended action (what to do about it)
- The source citation (so you can verify)
The supplement database includes vitamins (A, B6, B12, C, D, E, K2), minerals (calcium, iron, magnesium, zinc, selenium), adaptogens (ashwagandha, rhodiola, maca, ginseng), herbals (turmeric, ginkgo, garlic, saw palmetto), and more.
Some Surprising Synergies
Not all interactions are bad. The tool also highlights beneficial combinations:
- Vitamin D + Magnesium: Magnesium is a cofactor that activates vitamin D. Without enough magnesium, your vitamin D supplement doesn't fully activate.
- Glucosamine + Chondroitin + MSM: The classic joint health trio — each works by a different mechanism, and the combination outperformed individual supplements in the GAIT clinical trial.
- NAC + Vitamin C: They form a complete antioxidant recycling cycle — NAC regenerates glutathione, vitamin C regenerates NAC.
Technical Details
The tool is built as a zero-dependency, single HTML file:
- Frontend: Vanilla JavaScript, CSS Grid, no frameworks
- Data: JSON arrays embedded in the script
- Search: Client-side fuzzy matching on supplement names + aliases (Spanish and English)
- Mobile: Responsive design, works on any screen size
- Embed: Includes iframe embed code for other sites to integrate
Total file size: ~36KB. Loads instantly, works offline after first load.
The Bigger Picture
This is part of Botánica Andina's free health tools, which also includes:
- An herb-drug interaction checker (150 plants × 30 drug classes)
- A caffeine half-life calculator
- An evidence-based supplement verifier with A-F grades
- A personalized Andean plant recommendation quiz
All tools are free, open, and embeddable. We built them because Spanish-speaking health consumers have almost zero access to evidence-based interactive tools — while English speakers have Examine.com, Drugs.com, and dozens of calculators.
Try It
Check your supplement stack now →
If you run a health blog or pharmacy website, the tool includes a free embed code — just copy the iframe snippet at the bottom of the page.
I'd love feedback. What supplements should I add? What interactions am I missing? Drop a comment.
All interaction data sourced from peer-reviewed studies published in PubMed, EMA monographs, and clinical practice guidelines. This tool is informational — always consult your healthcare provider before combining supplements.
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