Stack Interaction Checker
Nobody takes one supplement. Select everything you take — supplements, peptides and medication — and see every documented interaction between them, ranked by how much it matters.
What you take
What we found
Tick what you take on the left. Results appear here as you go — nothing is sent anywhere.
This does not replace a pharmacist. It checks our own interaction data, which covers the supplements and peptides on this site — not the full drug-interaction literature, and not your specific prescriptions or conditions. If you take prescribed medication, run any new supplement past a pharmacist or your GP. They will do this properly and it costs nothing.
Re-check when your stack changes
We add compounds and interactions as the evidence lands. One email a week with what changed and what is worth trying.
How this works, and what it misses
Every compound on this site carries a list of documented interactions. This tool matches those lists against each other and against the medication classes you tick, then sorts what it finds by how the source note is worded — an interaction that says "avoid" ranks above one that says "monitor".
The important limitation is coverage. Our data describes the compounds we have written up, not the whole interaction literature, and the overwhelming majority of supplement and peptide combinations have never been formally studied together. A clean result means nothing is recorded, not that a combination has been tested and cleared. Treat it as a first pass that catches the known problems, then ask a pharmacist about the rest.
Three interactions worth knowing even if you never use this tool: vitamin K2 works directly against warfarin, berberine stacks with diabetes medication to produce hypoglycaemia, and minerals such as magnesium block levothyroxine absorption unless you separate them by several hours.