The FDA publicly posted five warning letters in September 2026 to peptide companies over semaglutide, tirzepatide, retatrutide, and other peptides, including products labeled for research use that the agency determined were intended as drugs for human use.
FDA Warning Letters Highlight Human-Use Marketing of Research Peptides
On September 1, 2026, the FDA publicly posted five warning letters involving peptide companies in Arizona, Florida, North Carolina and Texas. Issued August 24, the letters identify semaglutide, tirzepatide, retatrutide, and other peptide products that the FDA stated were unapproved new drugs, including products marketed for research use but determined to be intended for human drug use. The warnings add compliance context for Med Spa and wellness operators evaluating injectable products and product sourcing.
Five Companies Cited for Unapproved Peptide and GLP-1-Related Products
Among the warning letters the FDA publicly posted on September 1 were five letters issued August 24 to peptide companies after reviews of their websites in July 2026. Each letter identified unapproved new drug violations and cited website content that the FDA said established intended human drug use despite research- or laboratory-use labeling.
Peak Performance Peptides — Arizona
The FDA identified retatrutide, semaglutide, SS-31, PT-141, tesamorelin, and “Bac water.” The letter cited claims involving weight management, glycemic control, sexual function, and body composition.
Royal Peptides LLC — Florida
The FDA cited tirzepatide, semaglutide, retatrutide, SS-31, PT-141, tesamorelin, and BIMORELIN. The agency also referenced bacteriostatic water marketed alongside a peptide guide and calculator as evidence related to injectable preparation.
Peptide Partners LLC — Florida
The letter identified semaglutide, tirzepatide, retatrutide, SS-31, tesamorelin, PT-141, and a BAC reconstitution solution. Cited website claims addressed blood sugar, weight reduction, kidney effects, metabolic health, and other physiological effects.
NuScience Peptides LLC — North Carolina
The FDA identified tirzepatide, semaglutide, retatrutide, survodutide, mazdutide, PT-141, Tesamorelin Research Peptide, Tesamorelin Ipamorelin Blend, and bacteriostatic water. The agency also cited bacteriostatic water marketed alongside a peptide calculator that it said provided the means to prepare an injectable drug for human administration.
TXP Innovations LLC (Tex Peptides) — Texas
The FDA cited semaglutide, tirzepatide, retatrutide, SS-31, tesamorelin, PT-141, and bacteriostatic water. Website claims addressed glucose regulation, appetite, weight management, mitochondrial function, growth hormone, and sexual function.
Each recipient was directed to respond within 15 business days of receiving its letter with steps taken to correct cited violations, prevent recurrence, and provide supporting documentation. Across the five letters, the FDA stated that no approved applications were in effect for the identified products and that their introduction or delivery for introduction into interstate commerce violated sections 301(d) and 505(a) of the Federal Food, Drug, and Cosmetic Act.
Source: FDA Warning Letter Database
According to the FDA Warning Letter Database, five letters to peptide companies document findings from July 2026 website reviews and request written responses describing corrective and preventive steps for violations of the Federal Food, Drug, and Cosmetic Act.
FDA Compliance Context for Unapproved GLP-1 and Peptide Products
The five warning letters center on products represented as semaglutide, tirzepatide, retatrutide, and other peptides that the FDA identified as unapproved new drugs. The letters also address research- or laboratory-use labeling where website claims, injectable preparation materials, and related products, including bacteriostatic water for reconstitution, were cited as evidence of intended human drug use.
The warning letters raise compliance considerations involving:
- Unapproved new drug status
- Product labeling and intended use
- Research-use representations
- Injectable product preparation
- Product sourcing and distribution
The FDA cited unapproved drug marketing and evidence of intended human drug use despite research-use labeling.
The letters add to broader federal activity involving GLP-1 and peptide products. In March 2026, the FDA warned 30 telehealth companies over GLP-1 marketing, including marketing involving compounded semaglutide and tirzepatide. Separate litigation has also focused on investigational peptide products. In August 2026, Eli Lilly filed lawsuits involving products represented as retatrutide while the drug remained investigational and unavailable for lawful consumer sale.
The recent warning letters add another federal action involving peptide products marketed online. Med Spas, wellness companies, and healthcare operators handling GLP-1 or peptide products remain subject to applicable federal requirements involving drug approval, labeling, intended use, sourcing, and distribution.
Practical Implications for Med Spa and Wellness Operators
- Source GLP-1 and peptide products through lawful, appropriately regulated pharmaceutical channels.
- Confirm the regulatory status of each specific product, including whether an approved application is in effect where required.
- Match product labeling, marketing, and intended use with applicable federal drug requirements.
- Use preparation and reconstitution materials only within established legal and clinical pathways for the products involved.
- Document vendor identity, product source, purchasing records, and other information needed to support product traceability.
What to Watch Next
As of this reporting, the five companies had been directed to respond to the FDA within 15 business days. The FDA states that the reviews were conducted as part of its public health responsibility to protect the public from unsafe, ineffective, and poor-quality drugs. Future FDA updates or guidance may provide additional information on these cases and federal requirements for peptide and GLP-1 products.
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Image Attribution: “FDA Bldg 62 – Exterior” by The U.S. Food and Drug Administration, via Wikimedia Commons, licensed under Public Domain.
