Peptide Companies That Received FDA Warning Letters in 2026

The FDA issued warning letters to multiple companies in 2026 after reviewing their websites, inspecting facilities, or identifying other regulatory violations involving peptide-related and drug products. In the cited cases, the FDA identified website claims, product presentation, intended use, manufacturing practices, or other regulatory issues that supported its findings.

This article highlights 14 companies that received FDA warning letters in 2026 involving peptide-related products and other products marketed for drug-like uses, including semaglutide, tirzepatide, retatrutide, cagrilintide, mazdutide, tesamorelin, PT-141, SS-31, gonadorelin, and bacteriostatic or reconstitution solutions and other peptide-related products. In the cited warning letters, FDA determined that specific products were unapproved new drugs, based on its review of product labeling, website claims, intended use, and related marketing practices. Tirzepatide 20mg research vial is available from our catalog.

 FDA Warning Letter to Companies

The table below provides a quick overview of the companies discussed in this article, the dates of their FDA warning letter, and the primary products or regulatory issues identified by the agency.

FDA Warning Letter to GenoGenix LLC in January

GenoGenix LLC received an FDA warning letter on January 20, 2026, following an FDA inspection of its facility in July 2025. FDA identified semaglutide, tirzepatide, retatrutide, and Thymosin Beta-4 and determined that the products were unapproved new drugs. The agency also identified Thymosin Beta-4 as an unapproved biological product.

FDA Peptide Warning Letters Issued on March 31, 2026

On March 31, 2026, the FDA issued a group of warning letters involving peptide-related and GLP-1-marketed products. The companies included Gram Peptides, Prime Sciences, PekCura Labs, Lovega LLC dba Pink Pony Peptides, FormPour, Guangzhou Huli Technology Co., Ltd. dba Fantasy Face, and Mile High Compounds LLC. FDA determined that the specific products identified in these letters were unapproved new drugs under section 505(a) of the Federal Food, Drug, and Cosmetic Act. For a closer look, see our overview of research vs. compounded peptides.

1. Gram Peptides

FDA reviewed Gram Peptides’ website from January through March 2026 and identified retatrutide, tirzepatide, and Bacteriostatic Water for Injection. The agency stated that, although the products carried “Research Use Only” and “not intended for human consumption” language, evidence from the website established an intended use as drugs for human use. FDA also cited claims relating retatrutide to appetite suppression, insulin sensitivity, body-weight reduction, glucose handling, and lipid metabolism, while tirzepatide was associated with claims concerning glucose, insulin, weight management, and lipid profiles.

2. Prime Sciences

FDA’s March 31 letter to Prime Sciences identified cagrilintide, GLP1-R, GLP1-S, GLP1-T, mazdutide, and BAC water. FDA determined that these products were unapproved new drugs after reviewing the company’s website from January through March 2026.

3. PekCura Labs

For PekCura Labs, FDA identified GLP-1-S, GLP-2-T, GLP-3-R, and Bacteriostatic Water during its January 2026 review of the company’s website. The agency determined that these products were unapproved new drugs under section 505(a).

4. Pink Pony Peptides

Lovega LLC, doing business as Pink Pony Peptides, received a March 31 warning letter covering GLP-2 TZ, GLP-3 RT, and Bacteriostatic Water. FDA had reviewed the company’s website in December 2025 and concluded that the products were unapproved new drugs.

5. FormPour

FDA reviewed FormPour’s eBay store in December 2025 and identified an “SMGT-GLT-1 Nano Microneedle Patch” offered for sale in the United States. FDA cited website claims associating the product with Type 2 diabetes treatment, weight loss, and cardiovascular protection, and determined that the product was an unapproved new drug under section 505(a) of the FD&C Act.

6. Fantasy Face

Guangzhou Huli Technology Co., Ltd., doing business as Fantasy Face, received a March 31, 2026 warning letter after the FDA reviewed its eBay store in December 2025. FDA identified a “Googeer GLP-1 Weight Control Oral Solution” and cited claims concerning weight management, blood sugar balance, metabolism support, and body shaping. FDA determined that the product was an unapproved new drug under section 505(a) of the FD&C Act.

7. Mile High Compounds

FDA reviewed the Mile High Compounds company’s website and its linked community forum from January through March 2026. The cited products were GLP-1 SM, GLP-2 TRZ, GLP-3 RT, and BAC Water, which FDA determined were unapproved new drugs.

Wholesale Peptide Received an FDA Warning Letter in June

On June 17, 2026, FDA issued a warning letter to Wholesale Peptide after reviewing the company’s website in May. The agency identified Prostamax and Gonadorelin as unapproved new drugs. FDA cited specific website claims for Prostamax concerning prostate inflammation, enlarged prostate, bladder control, benign prostatic hyperplasia, and prostatitis. For Gonadorelin, FDA cited statements concerning testosterone production, testicular function, spermatogenesis, and investigations involving hormone-dependent cancers.

This case demonstrates why the scientific topic itself is not necessarily the regulatory issue. FDA specifically evaluated the intended use of the products based on claims appearing on the company’s website, including claims about treating conditions and producing physiological effects.

Five More Peptide Companies Received FDA Warning Letters on August 24, 2026

A second significant group of peptide-company warning letters was issued on August 24, 2026. The companies were Peptide Partners LLC, NuScience Peptides LLC, Royal Peptides LLC, TXP Innovations LLC dba Tex Peptides, and Peak Performance Peptides. FDA’s warning-letter database lists these five August 24, 2026 actions under the enforcement category “Unapproved New Drugs/Misbranded.”

Peptide Partners’ letter identified semaglutide, tirzepatide, retatrutide, SS-31 (elamipretide), tesamorelin, PT-141 (bremelanotide), and a reconstitution solution. FDA stated that the reconstitution solution was also a drug because the company sold it to reconstitute products intended for injection.

NuScience Peptides received a letter covering tirzepatide, semaglutide, retatrutide, survodutide, mazdutide, PT-141, tesamorelin products, and bacteriostatic water. FDA again determined these were unapproved new drugs and specifically noted the sale of bacteriostatic water for reconstituting injectable peptide products.

Royal Peptides’ cited products included tirzepatide, semaglutide, retatrutide, SS-31, PT-141, tesamorelin, and BIMORELIN. FDA concluded that these products were unapproved new drugs based on its review of the company’s July 2026 website content.

TXP Innovations, doing business as Tex Peptides, received an August 24 letter concerning semaglutide, tirzepatide, retatrutide, SS-31, tesamorelin, PT-141, and Bacteriostatic Water. FDA’s review of the company’s website occurred in July 2026. 

Peak Performance Peptides received a similar letter covering Bac water, retatrutide, semaglutide, SS-31, PT-141, and tesamorelin.

The scientific literature demonstrates that some compounds cited in these letters have been extensively investigated, but that scientific evidence is distinct from the regulatory status of a product sold by a particular company. For example, Wilding et al. (2021) demonstrated substantial weight loss with once-weekly semaglutide in a randomized clinical trial of adults with overweight or obesity. Similarly, Kingsberg et al. (2019) reported phase 3 trial findings for bremelanotide in women with hypoactive sexual desire disorder.

Why Peptide Companies Are Receiving FDA Warning Letters

The letters above share a set of recurring problems. The sections below explain the reasoning the FDA applies when it reviews research peptide sellers. This is covered further in this explainer on verifying peptide purity.

“Research Use Only” Does Not Automatically Resolve FDA Concerns

One of the clearest examples is the FDA’s March 31, 2026 warning letter to Gram Peptides. The FDA stated that the company offered retatrutide, tirzepatide, and bacteriostatic water for injection for sale in the United States. 

Although the products were labeled “Research Use Only” and “not intended for human consumption,” the FDA concluded that information on the company’s website demonstrated an intended use as drugs for humans.

The FDA specifically pointed to statements describing retatrutide in relation to appetite suppression, insulin sensitivity, body-weight reduction, glucose handling, and lipid metabolism. For tirzepatide, the agency cited claims concerning glucose, insulin, weight management, and lipid profiles.

This distinction is important: the FDA’s concern was not simply that Gram Peptides sold peptides. Rather, the agency determined that the overall product presentation suggested an intended use beyond laboratory research.

Therapeutic Claims Can Create a Regulatory Problem

The June 17, 2026 FDA warning letter to Wholesale Peptide provides another example. Following a review of the company’s website, FDA determined that Prostamax and Gonadorelin were unapproved new drugs.

For Prostamax, FDA cited statements claiming that the product could reduce prostate inflammation, help with an enlarged prostate, improve bladder control, and reduce symptoms associated with prostatitis.

For Gonadorelin, FDA cited statements concerning testosterone production, testicular function, spermatogenesis research, and investigations involving hormone-dependent cancers, including prostate cancer models. The agency concluded that these claims provided evidence that the products were intended to affect the structure or function of the body.

Therefore, the regulatory issue is not necessarily the scientific topic itself, but how a specific product is presented and the intended use that FDA determines from the available evidence. A company can discuss published research, but marketing a specific product in connection with treating a disease, reducing symptoms, or producing physiological effects can provide evidence that FDA considers when determining whether the product is intended for use as a drug.

Injectable Products Receive Particular Attention

The FDA has also emphasized the risks associated with injectable products. In the Gram Peptides warning letter, FDA stated that injectable drug products can pose serious risks because they may be delivered directly into the body or bloodstream, bypassing some of the body’s defenses against toxins and microorganisms.

The Wholesale Peptide letter similarly emphasized the potential for serious harm associated with injectable products.

This is particularly relevant to the online peptide market because some products are sold in formats associated with injection. In the Gram Peptides case, FDA went further and determined that the company’s sale of Bacteriostatic Water for Injection alongside peptide products requiring reconstitution supported the agency’s conclusion that the water was intended to be used for injection and therefore constituted a drug under the circumstances described in the letter.

FDA is Examining Websites as Evidence of Intended Use

Another important feature of the 2026 enforcement actions is the FDA’s reliance on publicly available website information.

For Gram Peptides, FDA stated that it reviewed the company’s website from January through March 2026 and used statements appearing on product pages as evidence of intended use. In the Wholesale Peptide case, FDA similarly identified violations during a review of the company’s website in May 2026.

This means that a disclaimer at the bottom of a website may not be sufficient if other pages contain claims that contradict the stated research-only purpose. The entire presentation of the product can matter, including product descriptions, claimed benefits, references to human outcomes, and other information that may indicate an intended use.

The Broader 2026 FDA Enforcement Environment

The peptide warning letters are also occurring within a broader 2026 FDA enforcement environment involving online marketing of drug products. For example, in March 2026, FDA announced warning letters to 30 telehealth companies concerning allegedly illegal marketing of compounded GLP-1 products.

Although these cases involve compounded drugs rather than research peptides, they illustrate a broader FDA focus on how drug products are described and marketed online.

FDA’s warning-letter database also makes clear that warning letters are regulatory notices identifying the agency’s concerns and allowing recipients to respond. A warning letter is a serious FDA regulatory communication, but it is not itself a final court judgment; the issues described may be subject to subsequent interaction between FDA and the recipient.

What the 2026 Warning Letters Mean for Peptide Companies

The 2026 cases provide a relatively clear lesson for companies operating in the research-peptide market.

A company that genuinely supplies materials for laboratory research needs to ensure that its product descriptions, marketing claims, website content, labeling, and supporting materials consistently reflect that purpose. Statements connecting a specific product to weight loss, disease treatment, symptom reduction, hormone effects, or other physiological outcomes can create significant regulatory exposure.

The Gram Peptides and Wholesale Peptide letters also show that simply adding “not for human consumption” or “research use only” does not necessarily prevent FDA from examining the company’s actual marketing practices.

What Happens After an FDA Warning Letter?

An FDA warning letter allows a company to address the agency’s concerns, but it should be taken seriously. In the Gram Peptides warning letter, the FDA instructed the company to notify the agency in writing within 15 working days of receiving the letter and to describe the specific steps taken to correct the violations, the measures being taken to prevent recurrence, and supporting documentation. FDA also warned that failure to adequately address the matter could lead to further regulatory or legal action, including seizure and injunction.

Wholesale Peptide was similarly instructed to respond within 15 business days and provide specific corrective measures.

For peptide companies, the message from these 2026 cases is therefore straightforward: research-use-only language must be supported by research-only marketing practices. Companies that make therapeutic claims or otherwise present products as intended for human use can attract FDA scrutiny even when their labels contain research-use disclaimers.

What the 2026 FDA Warning Letters Have in Common

Across the 14 FDA warning-letter cases involving peptide-related products discussed in this article, one of the most consistent issues is intended use. FDA’s 2026 warning letters show that website information can provide evidence of intended use, while facility inspections and manufacturing findings can also lead to regulatory action. Research-use language therefore did not automatically resolve the agency’s concerns when other website content indicated human use.

The letters also demonstrate FDA’s attention to injectable peptide products and products used to prepare them for injection. Several companies sold bacteriostatic water or reconstitution solutions alongside peptides that FDA considered injectable drugs. In the Peptide Partners and NuScience letters, FDA expressly treated these accompanying solutions as drugs based on how they were marketed and sold with the peptide products.

Conclusion

The FDA warning letters discussed in this article involve 14 companies and peptide-related or GLP-1-marketed products in 2026, including Gram Peptides, Prime Sciences, PekCura Labs, Lovega LLC dba Pink Pony Peptides, Mile High Compounds LLC, FormPour, Guangzhou Huli Technology Co., Ltd. dba Fantasy Face, GenoGenix LLC, Wholesale Peptide, Peptide Partners LLC, NuScience Peptides LLC, Royal Peptides LLC, TXP Innovations LLC dba Tex Peptides, and Peak Performance Peptides.

For companies operating in the research-peptide market, the 2026 warning letters provide concrete examples of the types of marketing practices that can attract FDA scrutiny. A research-use disclaimer is therefore only one part of the product presentation; the claims made throughout a company’s website and the way related injectable products are marketed can also become relevant to FDA’s regulatory analysis. We go into more detail in this explainer on peptide certificates of analysis.

References

1. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/genogenix-llc-718739-01202026 
2. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/gram-peptides-721806-03312026
3. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/prime-sciences-721805-03312026
4. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/pekcura-labs-721709-03312026
5. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/lovega-llc-dba-pink-pony-peptides-721088-03312026
6. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/mile-high-compounds-llc-721600-03312026
7. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/wholesale-peptide-729447-06172026
8. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/peptide-partners-llc-735063-08242026
9. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/nuscience-peptides-llc-733652-08242026
10. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/royal-peptides-llc-734884-08242026
11. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/txp-innovations-llc-dba-tex-peptides-735067-08242026
12. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/peak-performance-peptides-735127-08242026
13. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/formpour-722215-03312026
14. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/guangzhou-huli-technology-co-ltd-dba-fantasy-face-722228-03312026 
15. https://pubmed.ncbi.nlm.nih.gov/37366315/
16. https://pubmed.ncbi.nlm.nih.gov/33567185/
17. https://pubmed.ncbi.nlm.nih.gov/31599840/
18. https://www.fda.gov/news-events/press-announcements/fda-warns-30-telehealth-companies-against-illegal-marketing-compounded-glp-1s
19. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/compliance-actions-and-activities/warning-letters