Supplement interaction checker
Know what your supplements do to each other.
Conflicts, synergies and medication risks for your whole stack — with the evidence behind every rule — and a daily timeline that tells you when to take each one.
Every rule cites its sourcesNot medical advice
- supplements
- 93
- supplements
- interaction rules
- 65
- interaction rules
- medication checks
- 216
- medication checks
Interaction matrix
10 × 10
The checker
Build your stack
Free, no sign-up. Your stack is saved in this browser only and can be shared as a link.
Your stack · 0
Loading…
Paste your list
Presets
Medications & conditions
Optional. Stays in your browser — nothing is sent anywhere.
Results
Add two or more supplements.
You'll see conflicts, synergies and medication warnings — each with the evidence behind it — plus a daily timeline that keeps competing nutrients apart.
Common questions
Can you take them together?
Copper + Zinc
High-dose zinc can cause copper deficiency
Calcium + Iron
Calcium reduces iron absorption from the same meal
Iron + Zinc
Zinc and iron compete when taken together without food
Calcium + Magnesium
Very high calcium may reduce magnesium absorption
Magnesium + Zinc
Very high zinc can reduce magnesium absorption
Calcium + Zinc
Calcium may modestly lower zinc absorption
Curcumin + Iron
Curcumin binds iron
Iron + Vitamin C
Vitamin C boosts non-heme iron absorption
Vitamin D3 + Vitamin K2
D3 makes calcium-binding proteins; K2 activates them
Magnesium + Vitamin D3
Magnesium is required to activate vitamin D
FAQ
Questions, answered
How does the supplement interaction checker work?
Every pair in your stack is matched against a curated set of rules built from NIH fact sheets and peer-reviewed studies. Each rule lists its mechanism, a practical recommendation and an evidence level. Everything runs in your browser — nothing you enter is sent to a server.
How is the daily schedule created?
Each supplement has preferred times (for example iron on an empty stomach, fat-soluble vitamins with a meal). The planner then searches for the arrangement that honors those preferences while keeping competing nutrients apart and synergistic ones together — and keeps minerals away from thyroid medication if you flag it.
Does 'no interaction found' mean a combination is safe?
No. It means there is no documented interaction in our dataset. Always check with a pharmacist or doctor, especially if you take prescription medication.
Is it free?
Yes. There is no sign-up and your stack is saved only in your own browser.