Buying Retatrutide or Zenagamtide Online: What Lab Tests and Hospital Cases Show

Retatrutide and zenagamtide are two of the most talked-about weight-loss drugs in development. Eli Lilly makes retatrutide, and Novo Nordisk makes zenagamtide. Both are still in clinical trials, and no regulator anywhere has approved either one. Even so, a JAMA news report published on October 9, 2026 found dozens of websites selling them, often promoted by influencers on TikTok and Instagram.

What people buy online is not the same as what was tested in the trials. In an Australian lab test of three vials labeled 10 mg of retatrutide, the actual amount ranged from about 5 mg to 19 mg. Australia's drug regulator tested another vial sold as retatrutide and found no retatrutide at all, only a very high dose of semaglutide, the drug in Ozempic and Wegovy. Hospitals in Australia and Switzerland have reported patients made seriously ill after using these products.

This guide covers what the real drugs did in trials, what tests of online products have found, the hospital cases so far, and what the law says. For the wider problem of untested peptides, see our report on the peptide quality crisis.

Retatrutide is a weekly injection that activates three hormone receptors at once: GLP-1, GIP, and glucagon. These receptors help control appetite, blood sugar, and how the body burns energy. In TRIUMPH-1, a Phase 3 trial published in the New England Journal of Medicine in September 2026, 2,339 adults with obesity but no diabetes were randomly assigned to retatrutide or a placebo, a dummy shot, for 80 weeks. Average weight fell 25.0% on the 12 mg dose and 23.7% on 9 mg, compared with 3.9% on placebo. The most common side effects were digestive, such as nausea, diarrhea, and vomiting. In July 2026, Lilly said it planned to ask the FDA for approval in the first quarter of 2027.

Zenagamtide, formerly called amycretin, combines GLP-1 activity with amylin, a hormone that helps people feel full. In a Phase 2 trial in 262 adults with type 2 diabetes, presented in June 2026, the top 40 mg dose lowered body weight by 14.6% at 36 weeks. Novo began recruiting for AMAZE 9, a Phase 3 trial of zenagamtide tablets, on August 31, 2026.

In those trials, doctors started each person on a low dose, raised it slowly, and checked on them often. People buying online get none of that. If you are weighing whether to wait for the approved version, our guide Should I wait for retatrutide? covers the expected timeline.

Two sets of tests in Australia show the main problems.

The first was a small study by University of Queensland researchers, published as a letter in the journal Drug and Alcohol Review in August 2026. Three products sold as retatrutide were sent anonymously to a drug-checking service and analyzed by an accredited lab. All three contained retatrutide, but none contained the labeled 10 mg. One held 5.13 mg, about half the label. The other two held 19.0 mg and 16.5 mg, nearly twice and about two-thirds more than the label. The lab also found traces of lead, copper, and zinc, all far below harmful levels. It did not test whether the vials were sterile or free of endotoxins, bacterial fragments that can cause fever and shock when injected.

The second test came after a patient was hospitalized. In September 2026, Australia's Therapeutic Goods Administration (TGA) said a product sold as retatrutide contained no retatrutide. Instead, it held undeclared semaglutide at roughly eight times the level the TGA has found in semaglutide products it tested, according to ABC News's report of the TGA advisory.

Taken together, these results show three ways a vial can be wrong: too little drug, too much drug, or a different drug. Three samples cannot show how common each problem is, and the University of Queensland authors made that point themselves. One of the authors runs the testing service, which the paper disclosed.

Several reports describe people who needed hospital care after using these products. None of them proves that retatrutide itself caused the harm, because nobody can be sure what each person injected.

• A torn esophagus in Australia. The TGA's September 2026 advisory followed a case in which a person needed hospital care for a potentially fatal tear in the esophagus, the tube from the throat to the stomach, after uncontrollable vomiting. Their "retatrutide" turned out to be high-dose semaglutide.
• Liver injury in Victoria. On June 19, 2026, the Victorian Department of Health warned that it had received six reports of acute liver injury since January in people who used products labeled retatrutide, or nicknames such as "Reta," "R-10," and "R-20." Tests showed signs of liver inflammation, and some people had jaundice, a yellowing of the skin and eyes.
• Days of vomiting in Switzerland. Doctors at University Hospital Zurich reported in BMJ Case Reports on October 7, 2026 a woman in her mid-20s admitted after five days of nausea, vomiting, and loose stools that IV fluids and three anti-nausea drugs did not stop. A self-described life coach with no medical training had given her four weekly, rising doses of a product said to contain retatrutide. She had not thought of the shots as medicine, and she recovered within a week.
• U.S. adverse event reports. In a June 2026 report, the consumer group Public Citizen counted at least 14 hospitalizations linked to retatrutide in the FDA's adverse event reporting system, including cases of vomiting, a racing heartbeat, and ketoacidosis, a dangerous buildup of acids in the blood. Anyone can file these reports, and they do not prove cause, but the count rose from 10 reports in all of 2025 to 26 in the first five months of 2026.

The Zurich doctors made a practical point: many people do not mention wellness injections when a doctor asks what medicines they take. If you have used one of these products, tell any clinician who treats you.

Drugs in this class cause more side effects at higher doses and when doses rise too quickly. That is why trials raise the dose in small steps over many weeks. A vial with nearly twice the labeled amount can push a person past the dose their body has adjusted to, and a vial with half the amount can lead someone to inject more to make up for it.

The trials also turned up side effects that need watching. Retatrutide caused dysesthesia, an abnormal tingling or burning feeling in the skin, in some participants; in TRIUMPH-2, a Phase 3 trial in 1,152 people with obesity and type 2 diabetes published in The Lancet, it affected 4% to 7% of people on the drug versus 1% on placebo. Nausea affected up to 28% on the highest dose versus 8% on placebo. Our article on the retatrutide dysesthesia signal covers it in detail. In the trials, doctors could spot problems like these early. Someone injecting a product bought online usually has no one checking.

Because neither drug is approved, selling it for people to inject is illegal in the United States. Many websites label their vials "for research use only" or "not for human use" while posting dosing instructions, a practice regulators treat as a way around the rules.

• FDA: According to JAMA, the agency has sent 21 warning letters to companies selling retatrutide since December 2024. As of late September 2026, it had posted none to sellers of zenagamtide.
• State medical boards: Several have warned clinicians against prescribing unapproved peptides. In August 2026, Mississippi's boards of medicine, nursing, and pharmacy said that taking part in providing them is prohibited, JAMA reported.
• The drugmakers: Lilly told JAMA the online products are "entirely unverified, unapproved, and not worth the risk," and it has sued sellers.

The money trail behind these sites is covered in our report on the gray-market peptide supply chain.

Several approved weight-loss drugs are available now, including Wegovy (as a shot or a pill), Zepbound, and Foundayo. They have known doses, quality controls, and labels that list their risks. Prices have fallen in 2026, and our GLP-1 pricing guide compares current options. People who want to try retatrutide or zenagamtide before approval can ask a clinician about joining a clinical trial, where the drug is tested and the dose is monitored.

If you have already used a product bought online, Victoria's health department advises stopping it and seeing a doctor if you notice tiredness, stomach pain, itchy skin, dark urine, yellow skin or eyes, or easy bruising. Bring the vial or a photo of its label if you can. This article is not medical advice; a clinician who knows your history can help you choose a safe option.