50+ FDA Warning Letters in One Month: What September 2025 Means for You
The largest coordinated regulatory crackdown in peptide history. Who got hit, why, and what it signals about the future of the market.
What Happened
In September 2025, the FDA issued more than 50 warning letters to compounding pharmacies and manufacturers involved in the GLP-1 peptide market — the largest coordinated enforcement action in peptide history. Simultaneously, the agency established Import Alert 66-80 to intercept GLP-1 active pharmaceutical ingredients (APIs) with quality concerns at the border.
This wasn’t a gradual escalation. It was a regulatory air strike.
The Timeline That Led Here
To understand September 2025, you need to understand the two years preceding it.
September 2023: The FDA placed approximately 17 peptides — including BPC-157, TB-500, Thymosin Alpha-1, CJC-1295, Ipamorelin, and AOD-9604 — into Category 2 of the 503A bulk drug substances list, effectively prohibiting their compounding. This was the first major regulatory line in the sand.
2022–2024: Ozempic/Wegovy shortages were declared, temporarily authorizing compounding pharmacies to produce semaglutide copies under Sections 503A/503B. This created a multi-billion-dollar compounding market practically overnight.
February 21, 2025: The FDA officially resolved the semaglutide shortage, ending the legal authority for compounding. Compounding pharmacies were expected to stop producing semaglutide products.
March–August 2025: Many compounders continued production, using salt form variations (semaglutide sodium, semaglutide acetate) as a legal workaround. The FDA viewed these as distinct, unevaluated compounds. By April 2025, the agency had received 520 adverse event reports for compounded semaglutide.
September 2025: The hammer dropped. 50+ warning letters. Import alerts. The beginning of DOJ involvement.
What the Warning Letters Said
The warning letters targeted compounding pharmacies and manufacturers for:
- Distributing unapproved new drugs — semaglutide and tirzepatide products without valid compounding authority
- Using unevaluated salt forms — semaglutide sodium and acetate are not FDA-approved and may not be bioequivalent to the approved drug
- CGMP violations — manufacturing quality standards not met
- Misbranding — products marketed with claims not supported by the compounding exemption
Earlier in the enforcement wave (February 2024), warning letters went to US Chem Labs and Helix Chemical Supply for selling semaglutide and tirzepatide as “research chemicals” — extending enforcement beyond compounders to the research chemical market.
The Legal Battle
The enforcement triggered immediate legal challenges. The Outsourcing Facilities Association filed suit against the FDA (N.D. Texas, February 2025), arguing that the shortage determination was premature and that compounding authority should continue. Alabama’s Attorney General obtained a temporary restraining order against GLP-1 distributors in November 2025. Connecticut’s AG issued a statewide notice to medspas in May 2025.
By early 2026, the Department of Justice had become involved — signaling potential criminal prosecution beyond warning letters.
The Broader Enforcement Pattern
September 2025’s GLP-1 enforcement wave didn’t happen in isolation. The FDA had been tightening the noose on the broader peptide market for two years:
December 2024: The Pharmacy Compounding Advisory Committee (PCAC) voted against including ipamorelin, MK-677, CJC-1295, and AOD-9604 on the compounding bulks list, citing safety concerns. Each of these was a popular grey-market peptide.
January 2025: FDA final interim guidance eliminated Categories 2 and 3 entirely — substances remain prohibited, only Category 1 compounds can be compounded. What can still be legally compounded? Sermorelin, GHK-Cu (topical only), VIP, and NAD+. That’s essentially the complete list.
Late 2025: Warning letters to Summit Research Peptides, Xcel Peptides, and Pinnacle Peptides for research chemical sales — bringing enforcement to the “for research use only” market.
What This Means for Consumers
If you’re using compounded semaglutide:
The compounded product you’ve been using may no longer be legally available. Salt form variations (sodium, acetate) that some compounders offer are not FDA-evaluated and may differ in bioavailability, potency, or safety from approved semaglutide. Novo Nordisk’s Oral Wegovy 25 mg tablet (FDA-approved December 2025) is now available at $149/month — a legitimate, quality-controlled alternative.
If you’re using compounded peptides (BPC-157, TB-500, etc.):
Your compounding pharmacy may be operating in violation of FDA regulations. Category 2 peptides cannot be legally compounded under 503A or 503B. While the FDA hasn’t shut down all compounders overnight, the trajectory is clear: enforcement is expanding, not contracting.
If you’re buying from research chemical vendors:
The “research use only” market is no longer below the FDA’s radar. Warning letters to research chemical vendors in late 2025, combined with criminal precedent from earlier cases (All American Peptide, $3M+ forfeiture), indicate that this business model carries real legal risk — for vendors and potentially for buyers.
The Political Complication
The regulatory picture is complicated by political dynamics. Under the current administration, RFK Jr.’s allies have challenged the FTC’s substantiation requirement for supplement claims, and a lawsuit seeks to shift the burden so that the government would have to prove products don’t work, rather than requiring companies to prove they do. The MAHA (Make America Healthy Again) movement has criticized FDA enforcement against compounding pharmacies.
Additionally, more than 40 state attorneys general sent a joint letter to the FDA describing counterfeit and contaminated peptides entering the US through unregulated channels — creating cross-cutting political pressure.
Whether political pressure slows or accelerates enforcement is unknown. What is clear is that the regulatory infrastructure for enforcement now exists and has been demonstrated at scale.
What’s Compoundable, What’s Not
As of February 2026, the current landscape:
Category 1 (Legal to compound): Sermorelin, GHK-Cu (topical only), VIP, NAD+
Prohibited: BPC-157, TB-500/Thymosin Beta-4, Thymosin Alpha-1, CJC-1295, Ipamorelin, AOD-9604, Melanotan II, LL-37, MOTS-c, KPV, Selank, Semax, DSIP, Epitalon, PEG-MGF
Approved drugs (prescription only): Semaglutide, tirzepatide
The Bottom Line
September 2025 marked the moment the FDA demonstrated it would use its full enforcement toolkit — from warning letters to import alerts to DOJ referrals — against the peptide market at scale. The era of benign neglect is ending. Whether you view this as consumer protection or regulatory overreach (reasonable people disagree), the practical reality is the same: the market is becoming more legally risky for both vendors and consumers, and that trend is accelerating.
Methodology
This analysis is based on FDA warning letter database searches, ClinicalTrials.gov records, federal court filings, PCAC meeting transcripts, and independent journalism from STAT News, Bloomberg, and Reuters. Legal analysis draws from published commentary by FDA-specialized law firms (Holt Law, Frier Levitt, Mintz). PeptideExaminer has no financial relationship with any compounding pharmacy or peptide vendor.