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FAQ and troubleshooting

I get 401 unauthorized

  • API key required: the X-API-Key header is missing. Check the header name is spelled exactly and that your HTTP client actually sends it.
  • Invalid API key: the key is wrong, deactivated, or past its rotation grace period. Request a new one (API keys).

It works with curl but fails in the browser (CORS, "403")

Your website's origin isn't on the key's allowed list, so the browser blocks the response. The API doesn't send a 403; the browser shows a CORS error. Ask for your exact origin (scheme + host + port, e.g. https://myapp.example.com) to be added. Keys meant for servers usually have no origins and can't be used from a browser.

I get 429 rate_limited

You've used your key's requests for this minute. Wait the Retry-After seconds. Cache results, debounce autocomplete, or ask for a higher limit. See Errors and rate limits.

I get 502 upstream_error

The API couldn't reach a government data source and had no cached copy. These are usually brief: retry with backoff (1s, 2s, 4s). Persistent 502s on one endpoint are worth reporting.

My NDC isn't found

  • Use the product NDC with dashes, e.g. 00069-3150 or 0069-3150.
  • Leading zeros matter; don't strip them.
  • Products that were discontinued or never listed with the FDA won't be found. Try /v1/drugs/rxnorm/search by name instead.

The info card has empty sections

The newest label for that name is likely an over-the-counter "Drug Facts" label, which doesn't use the numbered prescription sections. Use /v1/drugs/spls?name= to pick a prescription label and fetch it by set ID.

A misspelled name returns nothing

/v1/drugs/autocomplete and /v1/drugs/info match names literally. Run the input through /v1/drugs/rxnorm/search first: it returns the closest matches and spelling suggestions.

Can I use this for clinical decisions?

No. It republishes FDA label text and NLM terminology to help people find information. The interaction check matches label text and can miss clinically important interactions.

Who do I ask?

Open an issue for keys, limits or bugs.