Free tool · no account

Supplement Combination Check

Pick two or more ingredients and see which known interactions, spacing rules and synergies exist between them, each with its source.

In short: The combination check shows you which known interactions, spacing rules and synergies exist between two or more ingredients. It is based on Stackwell’s synergy and conflict data; pairs whose statement was checked against a primary source (EFSA, studies, NIH) are shown with rationale and source, and the upper levels come from EFSA. The tool does not check interactions with medicines.

Your selection stays in your browser. It is not sent to Stackwell and not stored.

Choose ingredients

Frequently checked

Your selection

Nothing selected yet.

Examples:

Result

Pick at least two ingredients and the known notes will appear here.

Do you take any medicines?

Some supplements change how medicines work, and some medicines change how nutrients are absorbed. This tool does not check that. Talk to your doctor or pharmacist before taking supplements, especially during pregnancy and breastfeeding, with chronic conditions, and for children.

How the result is made

  • It is based on Stackwell’s synergy and conflict data, the same data the app uses to build daily plans.
  • Pairs whose statement we checked against a primary source (EFSA, studies, NIH) are shown with rationale and source. Every number appears as stated in the linked source.
  • Everything is computed in your browser. If you share the link, your selection sits after the # sign. That part of an address is never sent to a server.
  • Upper levels are taken from the EFSA overview: EFSA: Overview on Tolerable Upper Intake Levels, Version 11 (2025)

General information, not medical advice and not an individual dosage recommendation. Stackwell does not recommend products and does not sell supplements. A missing note does not mean a combination is harmless.

Frequently asked questions

What does the combination check check?
It shows which known interactions, spacing rules and synergies exist between two or more ingredients, each with its source, plus EFSA upper levels for adults.
Does the tool also check interactions with medicines?
No. Some supplements change how medicines work, and some medicines change how nutrients are absorbed. This tool does not check that. Talk to your doctor or pharmacist before taking supplements.
Where does the information come from?
It is based on Stackwell’s synergy and conflict data, the same data the app uses to build daily plans. Pairs whose statement we checked against a primary source (EFSA, studies, NIH) are shown with rationale and source. Upper levels are taken from the EFSA overview.
Is the upper level a dosage recommendation?
No. The tolerable upper intake level (UL) is the highest amount that is not expected to pose a health risk when taken daily over a long time. It is not a target and not a dosage recommendation. Lower values apply to children and adolescents.
Does a missing note mean the combination is harmless?
No. A missing note does not mean a combination is harmless.
Is my selection stored?
No. Your selection stays in your browser. It is not sent to Stackwell and not stored.
Do I need an account?
No. The combination check is free and works without an account.

Sources

The notes and upper levels on this page are based on these primary sources:

Your whole stack at a glance

In Stackwell you add your products with their ingredients. The app checks all ingredients together, puts pairs that should be taken apart into different intake times, and compares daily amounts with reference values. Getting started is free.

How to plan supplements and log your intake

Start for freeAlready have an account? Sign in
byitalli