What FDA Warning Letters Stopped Being About
In 2020, 63% of the warning letters FDA sent to drug, device and biologics companies mentioned COVID. In 2025 it was one letter out of 403.
From 2020 to 2022 most of the agency's written enforcement targeted something other than manufacturing. If your sense of what FDA cites was formed in those years, it is out of date.
We read the text of 1,976 warning letters issued by CDER, CDRH and CBER
between 2018 and September 2026, assembled from FDA's own sitemap because FDA
publishes no warning letter API. Every number below is produced by a script in the repository,
scripts/analyze-warning-letters.py, so it can be re-run and checked. The
letters themselves are searchable in our
warning letter search.
Quality unit citations fell to 3%, then recovered
A quality unit finding is the most basic CGMP citation: the unit responsible for approving and rejecting materials and procedures under 21 CFR 211.22 did not do its job.
| Share of letters citing | 2018 | 2020 | 2021 | 2024 | 2026 |
|---|---|---|---|---|---|
| Quality unit | 38% | 11% | 3% | 28% | 25% |
| Stability | 30% | 5% | 6% | 21% | 10% |
| Out-of-specification | 29% | 8% | 3% | 14% | 12% |
| Process validation | 25% | 7% | 5% | 20% | 13% |
| Data integrity | 17% | 4% | 2% | 11% | 8% |
In 2021 a quality unit citation appeared in 3% of letters, down from 38% three years earlier. Out-of-specification handling and data integrity fell just as far. Manufacturers did not get ten times better at quality in three years. The next table shows where the citations went.
COVID products took their place
Two other citations moved the opposite way over the same years:
| Share of letters citing | 2018 | 2020 | 2022 | 2026 |
|---|---|---|---|---|
| Marketing claims | 6% | 50% | 26% | 1% |
| Unapproved new drug | 10% | 70% | 47% | 45% |
| COVID mentioned | 0% | 63% | 40% | 1.5% |
Half of all letters in 2020 turned on marketing claims: products sold to treat or prevent a disease without an approval to say so. Seventy percent cited an unapproved new drug.
FDA pointed its enforcement capacity at products sold into a public health emergency, and it curtailed routine surveillance inspections at the same time. Warning letters follow inspections. Fewer inspections of manufacturing sites means fewer manufacturing citations, and it says nothing about the state of those sites.
That matters for anyone benchmarking. If you compared your risk profile against 2021 warning letters, you compared it against a year in which FDA was barely writing about manufacturing at all.
Manufacturing enforcement is back
By 2024 the quality unit is cited in 28% of letters, stability in 21%, process validation in 20%. Marketing claims are down to 3%. The 2026 figures hold near the same level, which puts citation patterns back close to 2018, with one exception.
Unapproved new drug citations stayed high
Marketing claims collapsed from 50% to 1%. Unapproved new drug citations did not: they sit at 45% in 2026, still four times the 2018 rate.
The products named are different. Of the 65 letters in 2026 citing an unapproved new drug, the recurring subjects are:
- compounding, by a wide margin
- stem cell products
- tirzepatide, semaglutide and other peptides
- nicotine products
This is GLP-1 compounding showing up in the enforcement record. FDA is using the same statutory provision it used against COVID cures in 2020.
If you are a compounder, a peptide supplier, or anyone marketing a product whose approved equivalent exists, this is the live enforcement front.
Using these numbers
If you benchmark against warning letters, leave out 2020 to 2022. Use 2018 to 2019, or 2024 onward.
A fall in citations is not evidence of lower risk. Quality unit citations fell from 38% to 3% and came most of the way back to 28%, and nothing suggests the sites themselves changed that much. The citation rate tracks where FDA spent its inspection time.
The unapproved new drug provision moved from COVID cures to compounded GLP-1s in about four years without any change to the statute. Where it is pointed next is the thing to watch.
Method
FDA publishes warning letters as individual web pages and provides no API for them. The public table serves 1,792 letters and its date filter does not work. FDA's sitemap, however, lists every published letter: 7,326 of them, of which 1,976 come from CDER, CDRH and CBER.
Each letter's full text was scanned for the citations above. Every figure here is a share of that year's letters, never a raw count. FDA de-publishes older letters, so counts before 2018 are thin for reasons unrelated to how many were issued, and treating them as enforcement volume would be wrong.
You can search the same corpus, filtered by deficiency, company, office and year, with our warning letter search. Background on what a warning letter is and what a response has to contain is in the glossary, along with the Form 483 that usually precedes one.