FDA peptide enforcement 2024–2026: letters and lawsuits

What we read

The FDA Warning Letters database for the period September 2024 through early October 2026 (the August and September 2026 letters read in full on fda.gov on 5 October 2026), filtered for actions citing 21 U.S.C. § 331 (misbranding and adulteration) against research-chemical and peptide vendors; DOJ press releases for the same period, filtered for charges referencing peptides, GLP-1 receptor agonists, or "research compounds"; contemporaneous reporting on The Peptide Catalog and Muscle and Brawn; and the publicly posted minutes from the FDA Pharmacy Compounding Advisory Committee meetings of October 2024 and April 2026.

Why the timeline matters

The US research-peptide market in May 2026 is structurally different from the same market in late 2024. Three forces converged: the criminal-case track against vendors that mixed scheduled substances into research catalogs; the FDA Warning Letter track against vendors making unapproved-drug claims; and the 503A compounding track that narrowed what compounding pharmacies could legally produce. Each track moved on a different schedule. The combined effect is what closed the top of the market.

A reader buying research peptides in May 2026 is buying in a smaller, more-disciplined catalog than the one that existed eighteen months earlier — and the regulatory environment continues to move. Knowing the chronology is the difference between reading a vendor's COA correctly and missing the context that explains why the vendor exists at all.

The chronology

For what border enforcement means for a buyer ordering from overseas, see peptides from China (10 October 2026): CBP told the Wall Street Journal it made more than 2,400 drug-product seizures between October 2025 and August 2026.

We have not printed a 2026 warning-letter total. The counts circulating online were compiled in the spring by third parties, and we have not recounted them against FDA's database.

Retatrutide is the exception. We counted 22 letters on fda.gov that cite it, 21 of them to sellers, and loaded every named site on 10 October 2026. Six still listed the drug or a code name with a cart button; the table is in who still sells retatrutide after an FDA letter. Download the data: the 22 letters are a CSV file on our data page.

What did FDA do about peptides in August and September 2026?

FDA dated five warning letters to research-peptide vendors on 24 August 2026 and posted them on 1 September. Each followed a review of the vendor's website in July 2026. Each named its GLP-1 products, usually by the vendor's own code name, as unapproved new drugs under section 505(a), and each gave the firm 15 business days to answer. Four letters list bacteriostatic water as a cited drug; the fifth, to Royal Peptides, raises it in a footnote.

Three things in these letters are new for this market.

FDA reads the code name back to the vendor. Four of the five letters quote a "GLP-1/2/3" alias and then write the real compound name next to it in brackets. The decoder is in our code-name catalogs piece, and the retatrutide aliases are on the GLP-3 RT page.

Bac water is evidence of intent. FDA's wording in the Peak Performance letter: "The sale of these products together demonstrates that you intend for your 'Bac water' to be used in combination for injection." The Royal letter adds that a "peptide guide" and "peptide calculator" sold alongside the vials "collectively provide the means to prepare an injectable drug for human administration."

Survodutide and mazdutide appear for the first time. The NuScience letter is the first FDA warning letter we have found that names either compound.

A third-party COA did not prevent a letter. Peptide Partners had published 11 certificates on Kovera between 13 June and 16 July 2026, three of them retatrutide lots, in the weeks before FDA's July website review. A certificate speaks to what is in the vial. FDA's letters are about what the vendor is selling it for.

The full product-by-product reading, with Lilly's complaints alongside, is in FDA's August 2026 peptide letters and Lilly's six lawsuits.

The Empower Pharmacy letter (18 September)

The other September letter went to a licensed 503A pharmacy, not an RUO vendor. After a November 2025 inspection, FDA told Empower Pharmacy in Houston that its tirzepatide/niacinamide and semaglutide/cyanocobalamin products "appear to be essentially copies of FDA-approved semaglutide and tirzepatide products," and that "the volume of products you are producing suggests that differences between products you are compounding and the FDA-approved products are pretextual." The letter also questions significant-difference statements chosen from "pre-selected menu options" on third-party prescribing platforms. What that means for the legal compounded channel is in our compounded semaglutide status page and the 503A analysis.

The North Sioux City search (23 September): what is and is not known

KTIV reported that the US Postal Inspection Service led a search, with the FBI and IRS Criminal Investigation, at Apex Waste Management, 503 Prosperity Way, North Sioux City, SD, and at a Dakota Dunes home on 23 September 2026. A follow-up KTIV report on 24 September found the same owners listed on an LLC named Apex Peptides, registered to an Iowa address. Third-party trackers report that the apex-peptides.com storefront shows a "Temporarily Closed" banner and lists the Prosperity Way address. When we loaded the site on 5 October we saw only a support widget.

No agency has said what the search concerned or named Apex Peptides. We have not confirmed that the storefront is the LLC KTIV found, or why it closed. Treat any claim that "Apex Peptides was raided" as unconfirmed until a charging document or agency statement appears. We keep the record, including the federal court search we ran on 10 October, in what happened to Apex Peptides.

Is Lilly suing peptide sellers?

Yes. On 12 August 2026 Eli Lilly filed six lawsuits over retatrutide, a drug that is still in Phase 3 and approved nowhere:

• Aesthetic Envy Cosmetic Centers (E.D. Cal.; voluntarily dismissed with prejudice on 11 September 2026, see Lilly has now sued 11 peptide sellers)
• Astra Peptides (W.D. Tex.; a 2 September 2026 notice dropped Astra LLC, and the case continues against the unidentified operator of "Astra Peptides")
• Legendary Peptides (E.D. Tex.)
• Striker Pharmacy (S.D. Tex.)
• Texas Peptides Inc. (W.D. Tex.)
• Lone Star Peptide Co. (S.D. Tex.)

In the same release, Lilly said it had referred more than 200 individuals and entities to FDA, DOJ, state attorneys general and licensing boards, and had reported more than 14,000 websites, ads, posts and listings in over 100 countries. It also asked "credit card companies, payment processors, shipping and logistics companies" to cut sellers off.

Reddit read it the same day. A thread titled "I'm a pharma attorney" concluded that "Unauthorized sale of Reta … may be coming to an end" (r/Biohackers). Six weeks later Chameleon Peptides told customers it was closing after its banks received Visa notices; that account comes from the vendor's own email and is in our closures piece.

These are civil suits brought by a drug company, not FDA actions, but they lean on the same evidence as the letters. Lilly's complaint against Lone Star Peptide cites the seller's "Peptide Calculator" and its "step-by-step guide" to reconstitution (paragraphs 51 and 56). Both the Lone Star and Legendary Peptides complaints point to r/Retatrutide as proof of a "thriving black market" (paragraph 39).

Track 1: the criminal cases

The criminal-case track is the one that closed three of the top five US peptide vendors by traffic. The cases share a structural feature: each began as a controlled-substances investigation rather than as a peptide-specific action.

Amino Asylum (June 2025). Federal authorities executed search warrants on Amino Asylum operations following a multi-year DOJ investigation. The charges concerned SARMs labeled products that contained testosterone — a Schedule III controlled substance under 21 U.S.C. § 802(41). The peptide catalog was not the formal subject of the action, but the operations ceased simultaneously. The vendor's audience — likely 200,000+ monthly visitors at peak — migrated within weeks.

Paradigm Peptides (operations ceased March 2024, sentenced 30 July 2026). This is the case that went furthest, and the only one in this article with a sentencing record. Owner Matthew Kawa was sentenced to 70 months in federal prison on 30 July 2026, with a $5 million money judgment. His sister and main employee Jennifer Stechkober received 16 months. Both pleaded guilty to introducing unapproved new drugs into interstate commerce with intent to defraud and mislead. Kawa admitted the company forged laboratory certificates, sold products it never tested, and imported from China and India while advertising US manufacture. Government testing of six compounds sold as SARMs found all six contained testosterone. The business ran 2019 to 2024 and reached roughly 54,000 customers in 80+ countries, continuing after FDA warning letters in 2020 and 2022. The verification implications are in forged COAs and a 70-month sentence. The full case record is on the Paradigm vendor profile.

Peptide Sciences (March 2026). The most recent of the three is unusual in that the formal cause was not a single criminal action but a quality collapse followed by federal pressure. We documented the COA trail in our Janoshik 7,164-tests purity analysis: 37 retatrutide samples failed Janoshik testing across 15 months, culminating in a counterfeit identification by Janoshik (mass-spec mismatch). Federal pressure followed the public quality data. The operations ceased on March 6, 2026.

The pattern across all three is the same: the formal cause of shutdown was not the peptide catalog. The catalog ceased operating because the parent operation was the formal target of action that implicated controlled substances or interstate misbranding.

Track 2: the Warning Letters

The Warning Letter track moved on a different cadence. Warning Letters are administrative — they cite specific marketing language, claims, or practices and require a response. They are not criminal, but they create the public record that often precedes criminal action.

December 2024 — first GLP-1 wave. The earliest Warning Letters in the period named vendors selling research-labeled GLP-1 compounds (semaglutide, tirzepatide, retatrutide) with marketing language that the FDA judged to constitute drug claims for unapproved products. The cited language varied — "weight loss," "fat loss," "appetite suppression" — but the core finding was uniform: research-only labeling on the product page, drug-marketing language elsewhere on the same site.

September 2025 — the enforcement sweep. The most consequential event in the Warning Letter track was the September 2025 sweep, in which the FDA issued 50+ Warning Letters in a coordinated wave against research-peptide and supplement vendors. The volume was the news. The cited issues clustered into three categories:

• Drug claims for unapproved products (the December 2024 pattern, at scale)
• Mislabeling — research-only language with consumer-facing marketing
• Manufacturing-quality citations — facilities not registered as drug manufacturers producing what the FDA classified as drug products

Vendor responses to the September 2025 sweep were uneven. Some vendors removed the cited claims and continued operating. Some vendors restructured catalogs (removing the GLP-1 SKUs entirely). Some vendors closed.

March 2026 — Gram Peptides and Prime Sciences. Two further Warning Letters in March 2026 named Gram Peptides and Prime Sciences specifically. The cited issues followed the established pattern (drug claims, misbranding) but with explicit references to the September 2025 sweep — i.e., the FDA was tracking which vendors had not corrected the previously-cited language. The implication for buyers: the FDA's pattern is to issue Warning Letters first and follow with stronger action against non-responders.

Track 3: the 503A compounding restrictions

The third track is the one most likely to reshape the legal market over the next 18 months. Section 503A of the Federal Food, Drug, and Cosmetic Act governs traditional compounding pharmacies — pharmacies that prepare individualized prescriptions for specific patients. Section 503A includes a "do not compound" list: substances that compounding pharmacies are not permitted to use under the 503A exemption from full drug approval.

October 2024 — tirzepatide added. The FDA Pharmacy Compounding Advisory Committee voted in October 2024 to recommend adding tirzepatide to the 503A do-not-compound list, citing the safety and efficacy concerns of compounded versions during the brand-product shortage period. The vote did not immediately bind compounding pharmacies, but it set the policy direction.

Compounding-shortage end. Throughout 2024 and into 2025, the shortage exemption that allowed compounded semaglutide and tirzepatide to be legally produced began to wind down. FDA confirmation that the brand product was no longer in shortage removed the legal cover under which compounding pharmacies had operated. The compounded GLP-1 market — which had been substantial — contracted accordingly.

April 2026 — PCAC reaffirms. At the April 2026 PCAC meeting, the committee reaffirmed the compounding restrictions on the GLP-1 class, extending the regulatory direction set in October 2024. The practical effect: licensed-compounding-pharmacy access to GLP-1 compounds is permanently narrower than it was in 2023–24.

This track does not directly close research-peptide vendors. It closes the adjacent legal market — compounded telehealth GLP-1s. The closure of the legal adjacent market is part of why research-peptide vendors saw demand surges in the same window: buyers who could not access compounded telehealth shifted to the research-peptide channel.

Track 4: the July 2026 reversal on non-GLP-1 peptides

Enforcement is not the only direction of travel. On 23-24 July 2026 the Pharmacy Compounding Advisory Committee recommended six of seven nominated peptides - BPC-157, KPV, TB-500, MOTS-c, Semax and Epitalon

• for the 503A Bulks List, against the advice of FDA's own review scientists. Emideltide was rejected. FDA had already removed twelve substances from the Category 2 do-not-compound list on 15 April 2026.

None of that legalised anything, and none of it applies to the research-chemical channel this article tracks. It runs alongside the enforcement escalation rather than replacing it, which means a buyer in August 2026 faces a compounding track that is opening slowly and a research-vendor track that is closing quickly. The full breakdown is in our FDA peptide vote explainer.

Track 5: enforcement outside the United States

US enforcement is the loudest track but not the only one. In July 2026 Health Canada was granted a permanent injunction against Canlab Research, a retailer of unauthorised injectable peptides. The company can no longer sell, distribute or advertise those products in Canada. The action followed multiple prior warnings from the agency, which cited risks including hormonal imbalance, blood sugar disruption, liver and kidney damage, blood clots and tumour growth.

Australian regulators and pharmacists have raised parallel concerns, reporting adverse events including anaphylaxis, liver injury and injection-site infections tied to unapproved peptides sold online, including retatrutide.

The relevance for a buyer in any country is that a vendor shipping internationally is exposed to more than one regulator, and an injunction in one jurisdiction can take a supply line offline everywhere it served.

What this means for the buyer

Three takeaways from reading the chronology end-to-end.

Vendor closures are not random. Each of the three top-tier vendor shutdowns followed a public regulatory or quality signal that was visible months in advance. The closures were not the result of sudden crackdowns; they were the result of slow, public-record processes that buyers had the option to track but mostly did not.

The Warning Letter is the single most useful public signal. A vendor named in a Warning Letter — and especially a vendor named in the September 2025 sweep — is a vendor on a track that frequently leads to either restructuring or closure. The FDA Warning Letters database is searchable by company name; it is the first place to check before ordering from any vendor.

The compounding track is the reason the research-peptide market matters. The squeeze on legal compounded GLP-1s is what created the demand pressure that the research-peptide market absorbed. As the compounding restrictions hold or extend, the research-peptide channel remains one of the few avenues through which a buyer can obtain GLP-1 compounds without a brand-product prescription. That is also the channel the FDA is most aggressively monitoring.

Sources

• FDA Warning Letters database — primary regulatory record
• FDA PCAC meeting materials — Oct 2024, Apr 2026 transcripts
• DOJ press releases — Amino Asylum, Paradigm Peptides
• FDA warning letters dated 24 August 2026, posted 1 September 2026: Peak Performance Peptides 735127, Royal Peptides 734884, NuScience Peptides 733652, Peptide Partners 735063, Tex Peptides 735067
• FDA warning letter 738238, Empower Pharmacy, 18 September 2026
• Lilly news release, 12 August 2026
• Lilly complaints: Lone Star Peptide (S.D. Tex.), Legendary Peptides (E.D. Tex.)
• USAO N.D. Ind., United States v. Matthew Kawa, updated 3 August 2026
• DOJ, counterfeit Ozempic indictment, 29 September 2026
• KTIV, North Sioux City search (23 September 2026) and Apex-tied businesses (24 September 2026)
• The Peptide Catalog vendor closures timeline
• Muscle and Brawn: Amino Asylum raid coverage
• Janoshik public tests database — quality-collapse evidence for Peptide Sciences
• Internal: Janoshik 7,164-tests purity analysis, three vendors closed in 12 months