Method·August 12, 2026 · 3 min read

The letter FDA doesn't have to post

FDA runs two advisory-action letters, not one. Warning Letters post to a structured database on a rule-bound cadence. Untitled Letters, issued for the same kinds of violations minus the enforcement threat, post only when FDA decides three named criteria are met — and the database a monitoring pipeline actually watches was never built to carry them.

By Connor Griggs — Regulatory & Quality Strategist

FDA’s Regulatory Procedures Manual names two advisory-action letters, not one. A Warning Letter and an Untitled Letter both put a violation on record. Only one of them is promised a place in a public, structured database the day it goes out.

Two letters, one threshold between them

Under Chapter 4 of the RPM, FDA issues a Warning Letter for violations it considers of regulatory significance — the kind that may lead to enforcement action if a firm doesn’t correct them promptly. The letter says so, in words: it warns the recipient that inaction can escalate. An Untitled Letter cites a violation that doesn’t clear that bar. It carries no such warning — the RPM is explicit that an Untitled Letter does not include a statement that failure to correct may result in enforcement action. Same office, same statute, a different letter for a violation FDA has already decided is the lesser one.

One is a database. The other is a decision.

Warning Letters are redacted and posted to fda.gov as a matter of course, so the public can read one without filing a FOIA request. Untitled Letters carry no such standing commitment. FDA posts one only after the Center decides posting is appropriate under one of three named conditions — three or more FOIA requests already anticipated, a belief that posting would inform the public about a health risk, or a belief that posting would deter the same violation elsewhere. Meet none of the three and the letter can exist, be issued, close a case — and never appear on a public page at all.

A Warning Letter is a promise to publish. An Untitled Letter is a maybe.

The page that holds both, and the tool that watches one

CDRH keeps a single page, Letters to Industry, that lists Warning Letters, Untitled Letters, and “It Has Come To Our Attention” letters side by side. The structured warning-letter search tool — the JSON endpoint behind fda.gov’s warning-letter database, and the one FDA Radar’s own pipeline reads — is scoped to Warning Letters specifically. An Untitled Letter, even a posted one, was never built to surface there. A monitoring practice keyed only to the Warning Letter database isn’t wrong about anything it shows. It is silent about a category of FDA correspondence that lives one page over.

Per what FDA Radar monitors and how often, this is regulatory intelligence about where CDRH publishes its own correspondence, never regulatory advice about how a specific firm should read a specific letter.

Primary sources

Regulatory intelligence, not regulatory advice. This post describes method and published FDA records as of its date; decisions about a specific device belong with your regulatory professional.

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