How to Join a Weight-Loss Drug Trial Instead of Buying It Online

Retatrutide is not approved anywhere. In the US, the only legal ways to get it before approval are a clinical trial or, for a small group of seriously ill patients, Lilly's expanded access programme.¹³ FDA says retatrutide "cannot be used in compounding under federal law," and it has warned companies selling it labelled "for research purposes" that such products are "of unknown quality and may be harmful to their health."⁴

So a trial is the right instinct. The honest answer on retatrutide itself, though, is that your chances right now are slim: on 23 October 2026 ClinicalTrials.gov listed no retatrutide weight-loss trial open to new volunteers in the US. Trials of other weight-loss drugs are recruiting in large numbers, and the search method below works for any of them. This guide gives no dosing information, recommends no products or sellers, and is not medical advice.

Is any retatrutide trial recruiting?

We queried the ClinicalTrials.gov database (API version 2) on 23 October 2026 for every study listing retatrutide as an intervention. Of 33 records, 21 were completed, 9 were "active, not recruiting" (under way but closed to new people), 1 was an expanded access programme, none was "not yet recruiting" and 2 were recruiting. The figures were unchanged from the day before.⁵

Neither recruiting study is a route in for most people reading this:

• SYNERGY-Outcomes (NCT07165028), a phase 3 Lilly trial, is for adults with fatty liver disease (MASLD) at higher risk of serious liver problems. Participants are randomly assigned to retatrutide, tirzepatide or placebo for about 224 weeks, with roughly 25 to 30 clinic visits. It lists 563 sites, 141 of them in the US. It is not a general weight-loss trial.¹⁰
• NCT07467447, a placebo-controlled phase 2 study in adults with obesity or overweight without diabetes, runs at one hospital in Shenzhen, China. Its record names a sponsor other than Lilly and was last updated in March 2026, so its status may be stale.¹¹

Lilly's dedicated weight-loss trials, including TRIUMPH-5, -6, -8 and -9, are already full.^12131416 Be wary of broad keyword searches, too: a general search for "retatrutide" also turns up a recruiting study that tests a smartwatch and exercise programme and supplies no retatrutide.⁵

Nobody outside Lilly knows when new US retatrutide weight-loss trials will open. Our retatrutide price and approval guide covers when it might reach pharmacies instead.

The realistic option: trials of other weight-loss drugs

The same day, a search for the condition "obesity", limited to interventional drug studies that were recruiting or not yet recruiting, returned 560 studies worldwide, 221 of them listing a US location.⁵ Most will not fit you, but this is where your real chances lie. Our pipeline guide explains which newer drugs are furthest along, which helps if you want to search for one by name.

How to search ClinicalTrials.gov

ClinicalTrials.gov, run by the US National Library of Medicine, lists studies but does not run them: "You can't sign up for a clinical study from ClinicalTrials.gov."⁸

1. Go to ClinicalTrials.gov and type obesity in Condition/disease. Enter one condition at a time.⁸
2. Add a drug if you have one in mind. Under More Filters, enter its name in Intervention/treatment, then repeat with its code name (for retatrutide, LY3437943).
3. Filter by status. Under Study Status, choose Recruiting and Not yet recruiting. Contact details appear only on studies looking for participants.⁸⁹
4. Set your location. Enter your address or zip code and how far you are willing to travel.⁸
5. Narrow the list by age, sex and study type. "Interventional" removes studies that give no treatment.
6. Open each record and check five things. The overall status and the date it was last verified. The Interventions section, to confirm the drug you want is actually given. The arms: a "placebo comparator arm" means some participants get placebo.⁹ The eligibility criteria (see below). And the brief summary, for length and number of visits: TRIUMPH-8, for example, lasts about 65 weeks with about 18 visits.¹²
7. Contact the study team through Contacts and Locations. If you hear nothing, the record may be out of date; try another site or ask your doctor.⁸

Searching outside the US

Lilly's retatrutide trials have run in many countries.¹⁰¹⁵ Other registries to search:

• Worldwide: the WHO ICTRP search portal combines records from national registries, including the EU and Australian New Zealand registries.²⁶
• European Union: the Clinical Trials Information System (CTIS), covering EU and EEA trials since January 2022.²⁷
• UK: Be Part of Research, an NIHR service "designed to help people find and volunteer for research studies across the UK", and the ISRCTN registry.²⁸²⁹
• Australia and New Zealand: the ANZCTR.³⁰
• Canada: Health Canada's clinical trial search portal covers authorised phase 1 to 3 drug trials but "is not used to recruit patients"; contact the sponsor instead.³¹

Would you qualify?

One rule matters most if you have been tempted by online products. Lilly's weight-loss trials exclude people who have taken weight-loss drugs, "including over-the-counter medications", in the 90 days before screening.¹⁶ Using a product bought online could rule you out for that period.

We read the eligibility sections of five Lilly weight-loss records. They overlap closely:^1213141516

• Weight: a BMI of 30 or more, or 27 or more with a condition such as high blood pressure, abnormal blood fats, obstructive sleep apnoea or heart disease. TRIUMPH-5 and TRIUMPH-6 simply require obesity.
• History: at least one unsuccessful attempt to lose weight by dieting.
• Diabetes: trials in people without diabetes exclude both type 1 and type 2 diabetes; Lilly runs separate trials for people with type 2 diabetes.⁵
• Exclusions: pancreatitis; a personal or family history of medullary thyroid cancer or MEN-2; a weight change of more than 5 kg (11 pounds) in the 90 days before screening; past or planned obesity surgery; and, in several trials, a recent heart attack, stroke or heart-failure admission.

The registry shows only key criteria. Full protocols add more, such as pregnancy rules; the China phase 2 record, for example, requires negative pregnancy tests.¹¹ The study team decides at screening, which can include blood tests and a physical examination. Many volunteers are screened to fill each trial, and "being excluded from one trial does not necessarily mean you will be excluded from another."¹⁸

What you are signing up for

A trial's protocol is reviewed by an independent ethics committee, an institutional review board (IRB), and the study team checks your health at scheduled visits. Trials testing a treatment are also watched by a data and safety monitoring board, which can stop a trial that is harming people.⁶²¹ Lilly says the clinicians running its trials "closely" monitor participants.²⁴ Products sold online have none of that oversight; our reports on gray-market retatrutide and whether online peptides are safe to inject show what testing of those products has found.

A trial is not a free supply of medicine, though. It exists to answer a research question, the experimental drug may not work for you, and it may cause side effects; our summary of retatrutide's side effects in trials shows what participants have reported.⁶ Taking part is voluntary, and FDA says "you can leave a study whenever you want."²² For background on what each trial phase can prove, see our guide.

Will you get a placebo?

Possibly. The arms section of the record shows the design, and retatrutide trials illustrate the three common ones:

• Placebo-controlled: TRIUMPH-1 randomly assigned 2,339 adults to one of three retatrutide doses or placebo for 80 weeks; average weight change was −25.0% at the highest dose and −3.9% with placebo.⁷ TRIUMPH-8 compares two doses with placebo in a double-blind design.¹²
• Active comparator: TRIUMPH-5 compares retatrutide with tirzepatide, with no placebo group.¹³
• Everyone starts on the drug: in TRIUMPH-6, all participants take retatrutide for 80 weeks, then some switch to placebo to test whether weight loss is maintained.¹⁴

You will be told before you join whether placebo is used, and in a blinded trial "it is always possible to find out which group you are in" if medically necessary.⁶ Our guides to randomised controlled trials and blinding explain why trials are designed this way.

Do trials pay, and what do they cost?

It depends on the study. FDA says paying participants "is a common and, in general, acceptable practice", treats it as a "recruitment incentive" rather than a benefit, and says the IRB should check that the amount and timing do not pressure anyone. Travel and lodging reimbursement are handled separately, and payment details belong in the consent form.¹⁹ ClinicalTrials.gov records "don't provide information about costs or payments", so ask the study contact.⁸ US rules say the consent process must explain whether compensation or treatment is available if you are injured, whom to contact, and, where relevant, any extra costs to you.²⁰

What happens when the trial ends?

NIH's National Institute on Aging says you should be told in advance whether you will keep receiving the treatment afterwards.¹⁸ Some retatrutide studies have extensions: TRIUMPH-1 offered about 500 participants up to 24 more weeks of retatrutide, and SYNERGY-Outcomes describes an optional 2-year extension on retatrutide or tirzepatide "even if they received placebo in the main study."¹⁰¹⁵ Neither promises long-term supply. After stopping a weight-loss drug, weight regain is common; see stopping semaglutide or tirzepatide.

Expanded access: the narrow alternative

Expanded access, or compassionate use, is for patients with a serious or life-threatening condition who have no satisfactory alternative and cannot join a trial.² An investigational drug given this way still needs a doctor and regulatory sign-off. Lilly's single-patient retatrutide programme requires all of the following:³¹⁷

• age 18 or older;
• a BMI of 35 or more despite approved weight-management treatment at the highest available dose;
• two or more serious or life-threatening obesity-related complications;
• being unable to join a retatrutide or similar trial, because of its rules or distance;
• having discussed all standard options, including bariatric surgery.

You cannot apply yourself. Lilly says "patients and caregivers should be directed to their treating physician rather than contacting Lilly directly." The doctor must sign an agreement, apply to FDA for a patient-specific investigational new drug application and get IRB approval. Lilly provides the drug at no cost, does not ship to patients directly, and says availability depends on "geography, product supply" and individual assessment.³ Even when criteria are met, FDA notes, "there is no law or policy that requires a company to provide access."² Outside the US, a doctor contacts the local Lilly office, and the national regulator must approve.²⁴

The US Right to Try law is a separate route for people with a life-threatening condition; FDA does not review those requests and companies need not supply the drug.²³ We found no Lilly statement offering retatrutide that way.

How to spot a fake trial

The US Federal Trade Commission says: "Never pay to be part of a clinical trial, or to find out about one." A real study "should never ask you to give your Social Security number during recruitment or screening," and you should never share bank details.²⁵ ClinicalTrials.gov does not send messages about studies or match people to them.⁸ Treat any "retatrutide study" that asks for a fee, or any seller offering "trial supply" vials, as a warning sign. Check a study by its NCT number and contact the site listed on the official record.

Questions to ask before you sign

Drawn from NIH and FDA guidance:^6181920

• Placebo: What are my chances of getting placebo or a comparison drug? Will I learn which I had?
• Visits: How many visits, how long, and can any happen near home?
• Costs: Will anything cost me money? What happens if I am injured?
• Payment: Will I be paid or reimbursed for travel, and when?
• Side effects: Whom do I call, day or night, if I feel unwell? (If you need urgent care during a trial, tell the staff you are in one.)
• Afterwards: Can I keep taking the drug after the trial? Will you share the results?
• Privacy: Who will see my medical records, and how are they protected? US consent forms must say how confidential your records will be and that FDA may inspect them.²⁰

Take the answers to your own doctor, who can also tell you whether an approved weight-loss medicine would suit you now.