Retatrutide has become one of the most searched medicines in the United States before it has even been approved. People have read the trial headlines, seen the before and after posts, and want to know two things: when they can get it, and whether there is any way to get it sooner. This guide answers both plainly. It explains what retatrutide is and what the trials have shown, where Lilly is in the approval process, why the "retatrutide" sold online is not a legal or safe route, which clinical studies are actually still enrolling in the US, and how research into other next generation weight loss medicines works for people who do not qualify for those.
Waiting for retatrutide?
The next generation of weight loss medicines is being tested now, and studies are enrolling adults with obesity, with or without related conditions
What retatrutide is
Retatrutide is an investigational once weekly injection from Eli Lilly that acts on three hormone receptors involved in appetite and metabolism: GLP-1 and GIP, which are the targets of tirzepatide (Zepbound and Mounjaro), plus glucagon. The triple action is the reason for the attention: in its first Phase 3 results, reported in December 2025, people with obesity and knee osteoarthritis on the highest dose lost on average more than a quarter of their body weight over 68 weeks, and later trials reported average losses of about 21 to 23 percent at the higher doses. The side effects were the familiar stomach ones, nausea, diarrhea, vomiting, and constipation, and the full safety picture is still being assembled from the remaining studies.
Our guide to obesity treatment options puts it in context with the approved medicines.
When retatrutide will be available
Retatrutide is not approved by the FDA, and no pharmacy can legally dispense it. Lilly has said it plans to submit the medicine to the FDA in the first quarter of 2027. FDA review typically takes most of a year after submission, so even on a smooth path, a prescription version is unlikely before 2028.The FDA has sent warning letters to companies selling compounded retatrutide, because an investigational drug cannot legally be compounded. Any website offering retatrutide for sale is selling an unregulated product.
Why "research peptides" are not retatrutide
Most of the top results for "how to get retatrutide" are online sellers offering vials labeled "for research use only." These products are not made under pharmaceutical standards, are not tested for identity, purity, or dose, and are not legal for human use. The FDA has warned about unapproved GLP-1 products, and the risks are real: the vial may contain the wrong dose, a different compound, or contaminants, and there is no clinical oversight for the side effects, which for a triple hormone drug are not trivial. If you are tempted because approved medicines are too expensive or not covered,the legal options are an approved medicine through a manufacturer savings program, one of the newly approved GLP-1 pills such as the Wegovy pill or Foundayo (orforglipron), or a clinical study.
Which retatrutide studies are still enrolling
Here is the part most people do not expect. The large Phase 3 obesity trials, the TRIUMPH program, have finished enrolling, so there is currently no US retatrutide study open for weight loss alone. As of October 2026, the one retatrutide study recruiting in the US is SYNERGY-Outcomes, a Lilly Phase 3 trial in adults with fatty liver disease (MASLD) and liver scarring measured by FibroScan, who are overweight or obese. It compares retatrutide, tirzepatide, and placebo, so taking part does not guarantee you will receive retatrutide. It runs at more than 140 US sites. If you have been told you have fatty liver with fibrosis, this is currently the only US study where retatrutide is one of the treatments being tested; our guides explain what FibroScan results mean and how fatty liver is treated.
If you do not qualify: other next generation medicines in trials
Retatrutide is one of several new approaches, not the only one. Studies now enrolling in the US are testing other investigational weight loss medicines, including ones designed to be easier on the stomach, to be taken by mouth, or to work through different hormone pathways. These studies enroll adults with obesity or overweight, with or without conditions such as type 2 diabetes, high blood pressure, or sleep apnea; most require that you are not currently taking a GLP-1 medicine, and a few are designed for people already on one. Joining a study is not the same as getting a prescription: you may receive the investigational medicine or a placebo, you cannot choose which, you attend regular visits, and the medicine's risks are still being studied. In return you get close medical monitoring and study related care, and you help answer the question everyone searching for retatrutide is really asking: whether the next medicine is better.
Our guide explains how placebo controlled trials work.
How to find a study
AllClinicalTrials.com lists weight loss and fatty liver studies recruiting across the US, and you can filter them by location before applying. Right now that includes a group of studies of new weight loss medicines for adults with overweight or obesity, and, for people with fatty liver disease, a group of studies for adults with diagnosed fatty liver disease or MASH who are overweight and have a related condition such as type 2 diabetes or high blood pressure. The application takes about 5 minutes: you answer questions about your weight, health conditions, and current medicines, and if a study near you looks like a match, the research team contacts you. Nothing is decided until you have gone through informed consent, and participation is voluntary at every step.
Three things to have ready: your current height and weight, your health conditions including any liver test or FibroScan results, and any weight loss medicines you have taken and when.
Common questions
Is retatrutide FDA approved? No. As of October 2026 it is investigational. Lilly plans to submit it to regulators in the first quarter of 2027.
When will retatrutide be available? Not before the FDA reviews it, which usually takes most of a year after submission. On a smooth path, a prescription version is unlikely before 2028.
Can I buy retatrutide online? Not legally or safely. Products sold as retatrutide "for research use" are unregulated, untested for dose or purity, and not approved for human use. The FDA has warned about unapproved GLP-1 products.
Can I get retatrutide through a clinical trial? Only if you qualify for a study that is still enrolling. The obesity trials have finished enrolling; the US study open now is for adults with fatty liver disease and scarring who are overweight. Participants may receive retatrutide, tirzepatide, or placebo.
How much weight did people lose on retatrutide? In the first Phase 3 results, reported in December 2025, participants with obesity lost on average more than a quarter of their body weight over 68 weeks. Results from the rest of the program are still coming.
What are retatrutide's side effects? In trials so far, mainly nausea, diarrhea, vomiting, and constipation, similar to other GLP-1-based medicines, plus an unusual skin sensation called dysesthesia in some participants. The complete safety picture will come from the full Phase 3 program.
What are the alternatives while I wait? Approved medicines such as Zepbound and Wegovy, the newer GLP-1 pills (the Wegovy pill and Foundayo), and clinical studies of other investigational weight loss medicines, some designed for people who could not tolerate GLP-1 medicines.
Do weight loss trial participants get paid? Some studies offer compensation for time and travel, and study related care is typically provided at no cost to participants. Compensation varies by trial and is always described during the informed consent process before you agree to anything.