How to Join a Retatrutide Trial: Steps, Eligibility, and What to Expect

To join a retatrutide trial, start by searching ClinicalTrials.gov or Eli Lilly's clinical trial portal for active studies, confirm you meet the basic eligibility criteria, and contact the nearest research site to begin screening. Retatrutide is an investigational drug, so clinical trials are the only legal way to access it in the United States. The process usually takes several weeks and includes a phone pre-screen, an in-person visit, and informed consent.

What Is Retatrutide, and Why Do People Join Trials?

Retatrutide (also known as LY3437943) is an investigational triple hormone receptor agonist that targets GIP, GLP-1, and glucagon receptors. It is being studied for obesity, type 2 diabetes, and related metabolic conditions.

Retatrutide is not FDA-approved for human use in the United States. That means you cannot get a prescription for it outside of a clinical trial. People join retatrutide trials to access the drug at no cost, receive close medical monitoring, and contribute to research that may lead to future approvals.

Trials are also the only way to receive pharmaceutical-grade retatrutide that has been tested for purity and dosing accuracy. If you have considered underground sources, note that trial participation avoids the risks of unregulated products.

How to Find an Active Retatrutide Trial

Finding a study is the first practical step. The TRIUMPH program is a series of Phase 3 retatrutide trials, and new studies may open at different times.

1. Search ClinicalTrials.gov. Use search terms like "retatrutide," "LY3437943," or "obesity." Filter by recruiting status and your state.
2. Check Lilly's trial website. Eli Lilly maintains a clinical trial finder that lists its own studies, including retatrutide.
3. Contact academic medical centers. Large research hospitals often participate in metabolic trials. Ask if they have any retatrutide studies open.
4. Sign up for trial alerts. Some sites let you join a waitlist or receive notifications when new studies launch.

Eligibility Criteria for Retatrutide Trials

Each study has its own rules, but most retatrutide trials share similar eligibility requirements. Common criteria include:

• Age 18 or older (some trials include adolescents).
• BMI of 30 or higher, or 27 or higher with at least one weight-related condition such as high blood pressure or high cholesterol.
• For diabetes trials, a confirmed diagnosis of type 2 diabetes and specific A1C ranges.
• Stable weight for a set period before screening.
• Willingness to use contraception if of childbearing potential.

Exclusions often include pregnancy, breastfeeding, a history of pancreatitis, certain thyroid cancers, severe kidney or liver disease, and recent use of other GLP-1 medications. If you are currently on Mounjaro or another GLP-1, you may need a washout period before enrolling. People often ask about how to switch from mounjaro to retatrutide, but in a trial the study doctor manages any transition and timing.

Eligibility criteria for retatrutide trials vary by study and typically include a minimum BMI and age requirement.

The Screening and Enrollment Process

Once you contact a site, the process usually follows these steps:

1. Phone pre-screen. A coordinator asks about your medical history, medications, and weight.
2. Informed consent. You review and sign a document explaining the study, risks, and your rights.
3. In-person screening visit. This may include blood tests, vital signs, an ECG, and a physical exam.
4. Eligibility review. The study team confirms whether you qualify.
5. Randomization. If eligible, you are assigned to a dose group or a placebo, often by chance.

If you are wondering how to reconstitute retatrutide or how much retatrutide to take per week, you do not need to worry about those steps in a clinical trial. The sponsor provides prefilled pens or vials, and the study team tells you the exact dose and schedule. Similarly, you do not need to learn retatrutide how to inject on your own because site staff demonstrate the injection technique and monitor you at visits.

Clinical trials are the only legal way to access retatrutide in the United States, and participants receive the drug at no cost.

What to Expect During and After the Trial

Retatrutide trials often last 48 to 104 weeks, depending on the phase and design. You may have visits every few weeks at first, then less often.

Many people ask how long does retatrutide take to work. In published Phase 2 data, participants began seeing weight changes within 12 to 24 weeks, with larger average reductions at higher doses over 48 weeks. Individual results vary, and some participants receive a placebo.

Trials usually provide reimbursement for time, travel, and procedures. The amount varies by site and study. After the blinded period, some trials offer an open-label extension where all participants can receive retatrutide.

Safety, Risks, and Questions to Ask

Retatrutide is still experimental, so its full safety profile is not yet known. Reported side effects in trials include nausea, vomiting, diarrhea, constipation, and injection-site reactions. Some participants experience an increase in heart rate.

Before enrolling, ask the study team:

• How many participants will receive placebo?
• What is the dose escalation schedule?
• Who pays for study-related tests and travel?
• What happens if I want to leave the trial early?
• Will I receive the drug after the study ends?

Talk with your healthcare provider before joining any clinical trial. A trial is not a substitute for routine medical care, and retatrutide is not a cure for obesity or diabetes.

Retatrutide remains an investigational drug, and no one should use it outside of a supervised clinical trial.