Methodology

Source hierarchy

We prioritize sources in roughly this order:

1. FDA-approved labeling and FDA safety communications
2. DailyMed / National Library of Medicine drug labels
3. NIH Office of Dietary Supplements fact sheets
4. PubMed-indexed primary research and systematic reviews
5. Clinical practice guidelines from recognized professional bodies
6. MedlinePlus, for patient-facing reference context

RxNorm is used for medication identity/normalization only, never as interaction evidence on its own.

Evidence quality labels

Every published interaction and timing rule is labeled with an evidence quality of high, moderate, low, or insufficient, reflecting the strength and directness of the sources it cites -- not how serious the interaction is. Severity (informational / monitor / caution / avoid / insufficient evidence) and evidence quality are tracked separately on purpose: a well-documented mild interaction and a poorly-documented serious one look very different, and collapsing that distinction would hide real uncertainty.

How pairs are researched

Candidate pairs come from real, high-intent user questions (common supplement combinations, common supplement/medication combinations), not from mechanically generating every mathematically possible pair. A candidate pair is only published once it has real sourced evidence behind it -- our database will not let a substance or interaction row be marked published without at least one linked evidence source; this is enforced by the database itself, not only by editorial habit.

How uncertainty is handled

When we have not reviewed a specific pair, the checker says so directly: "we do not currently have a reviewed interaction record for this pair." That is never converted into a claim that the combination is safe. When sourced timing/spacing rules disagree with each other, both are shown rather than picking one silently, and the page tells you to follow your prescription label and ask a pharmacist or clinician.

Review and updates

Content moves through draft, verification, and publication stages before it is public -- see the editorial policy for that workflow. Published pages show a last-reviewed date. Pages without a linked source, a meaningful summary, and a last-reviewed date are excluded from search indexing and the sitemap, even if technically published in the database.

Corrections

Anyone can report a suspected error via corrections. Reports are reviewed before any change is made; they are never auto-published.