Chinese producers of the ingredients that go into fentanyl have found a profitable new market in the U.S.: peptides.
TRM Labs, one of the analytics firms, has been tracking more than 200 companies that have sold fentanyl precursors. Out of those, at least 50 are currently selling peptides, a number that has been growing in recent months, said TRM. Based on crypto payments TRM has traced, the buyers of the products from these companies are both in the U.S. and elsewhere.
Chinese drug precursor manufacturers “have the know-how and the equipment to manufacture every single known substance on earth. Anhui Rencheng didn’t reply to a request for comment. The FDA works with federal agencies on investigations and enforcement actions, she added. Peptides are short chains of amino acids that can act as signaling messengers that might, for instance, tell the body to produce more growth hormone or repair tissue. The term technically encompasses a broad category of products that includes FDA-approved drugs—ranging from insulin to Ozempic—but it has become shorthand for substances people are injecting that haven’t undergone approval from the FDA. Several numbers and emails provided on the website are no longer in use. A request for comment sent through an online form hasn’t been answered. Attempts to reach the company were unsuccessful. Write to Patricia Kowsmann at [email protected] and Sara Ashley O’Brien at [email protected]
One Chinese company, Anhui Rencheng Technology, was indicted in 2023 by the Justice Department, which accused it of providing fentanyl precursors used by the Sinaloa and other Mexican drug cartels. Anhui Rencheng, which sells peptides and fentanyl precursors on its website, was among several Chinese companies indicted in 2023 for allegedly supplying fentanyl ingredients used by drug cartels. The company is also advertising a fentanyl precursor called 1-Boc-4-piperidone and a highly potent synthetic opioid called protonitazene, which is stronger than fentanyl and has caused deaths in the U.S. and elsewhere. Another company indicted in 2023 by the U.S. for its alleged role in the fentanyl trade is Anhui Ruihan Technology.
And nowadays there is a lot of demand for peptides, so peptides it is,” said Alois Afilipoaie, a senior blockchain analyst at TRM. It is now selling a peptide known for its tanning effects, called Melanotan II, and semaglutide—the active ingredient in Ozempic—in salt form, according to its website. Emily Hilliard, a Health and Human Services Department spokesperson, said the “FDA is concerned about the sale of unapproved drug products, including products marketed as peptides, to U.S. consumers. “In this era of health misinformation and distrust of institutions, people don’t appreciate the safety provided by the FDA regulatory and inspection system,” said Shabbir Imber Safdar, executive director of the Partnership for Safe Medicines, a public-health coalition focused on supply-chain safety. In the indictment, prosecutors said Anhui Rencheng chemists provided buyers with instructions on how to make fentanyl. Founded in 2015 in Hefei, a city northwest of Shanghai, Anhui Rencheng calls itself a professional chemistry manufacturer that prides itself “on the variety and quality of their products, which are sourced from the best possible raw materials and undergo a rigorous quality control process,” according to the website, which is in English and provides Chinese phone numbers of sales agents. It says it guarantees deliveries of its products, including to the U.S., and boasts of having warehouses in the U.S., Mexico, Canada and Germany. “We have powerful customs clearance agencies in these countries, and our customs clearance company will clear your parcel without any customs issues,” the company says. The company is actively advertising Retatrutide—Eli Lilly’s next generation weight-loss drug that isn’t yet approved by the FDA—on a platform called Chemical Book, according to an ad provided by TRM.
The findings illustrate the reckless way in which the market for peptides is developing. Most of the substances being marketed as peptides are unapproved drugs. As big pharmaceutical companies stay on the sidelines, black-market manufacturers, many in China, have filled the void. The suppliers are also competing with companies when it comes to Food and Drug Administration-approved peptide-based drugs peddling bootleg versions of weight-loss GLP-1s at much lower prices. Their purported benefits are largely anecdotal, but peptides are receiving endorsements from influencers, podcasters, alternative-medicine doctors, and even Health and Human Services Secretary Robert F. telehealth companies and alternative doctors have been supplying unapproved peptides to patients, many Americans order directly from online sellers While some med spas. Some are portioned out in small vials, while others are reconstituted from raw ingredients by agents or resellers who sell the peptides ready to use. In online forums, users trade tips and names of peptide suppliers both in the U.S. and abroad. Companies in China have long been the main producers of the chemical building blocks used to make fentanyl. As with peptides, these precursors were openly sold online. Buyers included drug cartels, which went on to make the drug and distribute it across the U.S. For years, the U.S. pushed China to crack down on the precursor producers. Chinese authorities have slowly taken steps to shut down sellers and enforce export controls on the substances. Many, however, have survived. Just like the fentanyl precursors, Chinese peptides are entering the U.S. market, at least in part, through a smuggling scheme known as “master cartons. They take orders from buyers in the U.S. and package multiple individual orders into a larger box that is mislabeled as containing legal goods, such as snacks. Once in the U.S., an associate then distributes the packages inside the carton. Buyers may not know their peptides originate from China. In December, Cincinnati Customs and Border Protection officers identified a master carton scheme from a Chinese shipper. Nationwide, the number of illicit pharmaceutical shipments being intercepted across the U.S. has jumped this fiscal year. It declined to comment on specific companies or ongoing investigations.
The transformative weight-loss effects of GLP-1-based medications have led consumers to question what other substances they could inject in a quest for self-optimization. Before 2025, the gray-market peptide ecosystem was a niche and underground, averaging just $200,000 in monthly purchases done using cryptocurrencies, according to the firm. But in 2025, the market began to grow. This year, peptide purchases in crypto have surpassed $10 million a month. The officers have since thwarted roughly 400 master carton smuggling attempts, involving nearly 6,000 pre-labeled shipments of peptides. From October 2025 to the end of August, there were more than 2,400 seizures of noncompliant or fraudulent products, involving more than 130,000 vials, according to the CBP.
Because they were cheaper, some U.S. buyers told The Wall Street Journal they zoomed in on Chinese suppliers.
Kennedy, Jr., who has said he is a “big fan. The products, which are often labeled as “for research use only” or “not for human consumption,” are powdered substances that must be reconstituted with bacteriostatic water and injected. Hilliard, the HHS spokeswoman, said the agency monitors the marketplace and has taken action against the sale of unapproved peptide products. “That lack of understanding of risk allows them to leave the safety of the regulated system without knowing what is lost when they do so,” he added. More recently, “some Chinese chemical manufacturers, facing increasing pressure from international law enforcement over the illicit drug precursor trade, have realized that the peptide market is a highly profitable and legally ambiguous next step,” analytics firm Chainalysis said in a report.
