Weight Loss & Body Composition
Retatrutide
An investigational triple-agonist weight-loss drug in Phase 3 trials; not yet approved or available.
Also called: LY3437943, triple agonist, reta
Used for
Weight Loss & Body Composition
Our pricing
$100 to $1,000+ depending on peptide and quantity
Studied for
Obesity and weight reduction (investigational) · Type 2 diabetes (investigational)
Retatrutide (LY3437943) is an investigational once-weekly injectable from Eli Lilly that activates three hormone receptors at once: GLP-1, GIP and glucagon. In a 2023 Phase 2 trial the highest dose produced roughly 24 percent average weight loss at 48 weeks, and the Phase 3 TRIUMPH program is still under way. No approved retatrutide product exists anywhere, so it cannot be legally prescribed or compounded; what is available now is FDA-approved GLP-1 medication such as semaglutide and tirzepatide inside a nurse-practitioner-supervised weight-loss program.
What is Retatrutide?
Retatrutide is the next step in a line of incretin-based weight-loss drugs. Semaglutide activates one receptor (GLP-1). Tirzepatide activates two (GLP-1 and GIP). Retatrutide adds a third, the glucagon receptor, which is thought to raise energy expenditure and reduce liver fat on top of the appetite and blood-sugar effects of the other two. It is still investigational, meaning it exists only inside clinical trials.
The headline data come from a Phase 2 trial published in the New England Journal of Medicine in 2023. Among 338 adults with obesity, those on the highest dose lost an average of about 24 percent of body weight at 48 weeks, and the curve had not flattened when the trial ended. Separate Phase 2 work in type 2 diabetes and a liver-fat substudy showed similarly large effects. Phase 3 trials, grouped under the TRIUMPH name, are enrolling or reading out across obesity, sleep apnea, knee osteoarthritis, diabetes and cardiovascular outcomes.
Because those results are striking, retatrutide is heavily marketed online by sellers who are not part of any trial. That product is not the investigational drug. It is unregulated, its identity and purity are unverified, and using it carries the risks of an unstudied injectable with none of the monitoring that trial participants receive. Every mention of retatrutide as a treatment on this page should be read with that word, investigational, attached.
What Retatrutide is studied for
The goals researchers and clinicians have focused on, and why patients ask about it.
Obesity and weight reduction (investigational)
The Phase 2 obesity trial reported roughly 24 percent average weight loss at 48 weeks on the highest dose, larger than published results for semaglutide or tirzepatide at comparable time points. Phase 3 obesity trials are ongoing, and approval decisions depend on their results.
Type 2 diabetes (investigational)
A parallel Phase 2 trial in people with type 2 diabetes showed meaningful reductions in A1c alongside weight loss. Phase 3 diabetes trials are part of the TRIUMPH program.
Liver fat (investigational)
In a substudy of participants with fatty liver disease, the higher doses reduced liver fat by a large majority within 48 weeks, with many participants reaching normal liver-fat levels. This is an early but closely watched finding.
Sleep apnea, knee osteoarthritis and heart outcomes (investigational)
Phase 3 trials are testing retatrutide in obesity-related sleep apnea, knee osteoarthritis pain and cardiovascular risk, following the pattern set by semaglutide and tirzepatide. No results in these conditions are available yet.
The human side
What patients commonly report with Retatrutide
Clinical trials move slowly; patient experience moves faster. Here is what people using Retatrutide under clinical supervision most often describe. Results vary from person to person.
Substantial, continued weight loss throughout the trial period
Reduced hunger and easier portion control described by trial participants
Noticeable improvements in energy and mobility as weight decreased
Meaningful drops in liver fat reported in the liver-focused substudy
How Retatrutide is typically used
Inside clinical trials, retatrutide is a once-weekly subcutaneous injection with a gradual dose escalation to limit stomach side effects, the same shape as existing GLP-1 therapy. Outside a trial there is no legitimate use, no approved dosing and no pharmacy legally permitted to compound it.
What is available now, and what a nurse practitioner will actually discuss, is FDA-approved GLP-1 therapy. Semaglutide and tirzepatide are prescribed inside a medically supervised weight-loss program that includes a health history, baseline labs, body-composition tracking with InBody, nutrition and training guidance, and regular follow-up. That structure, not the specific molecule, is what drives durable results.
For readers deciding between options, our comparison of semaglutide, tirzepatide and retatrutide lays out what each has shown in trials and which are prescribable today. If retatrutide is eventually approved, this page will be updated to reflect its status and how it fits alongside existing therapy.
Who tends to do well with it
Adults who have read about retatrutide and want the closest legitimate option available now: FDA-approved semaglutide or tirzepatide inside a supervised program
People who meet clinical criteria for GLP-1 therapy and want a nurse practitioner to evaluate which approved medication fits their health history
Patients who want to understand what Phase 3 results could mean for their future options while getting started on proven treatment today
When we take extra care
Anyone offered retatrutide outside a registered clinical trial; no legitimate prescription or compounded version exists anywhere
People with a personal or family history of medullary thyroid cancer or MEN2, a class warning that applies to all GLP-1 medications
People with a history of pancreatitis or severe gastrointestinal disease
Pregnant or breastfeeding patients, or anyone planning pregnancy
Anyone with a history of eating disorders, where rapid weight loss requires close supervision
Anyone expecting medication alone, approved or investigational, to replace nutrition, training and follow-up
What to know before you start
In trials the most common side effects were gastrointestinal: nausea, vomiting, diarrhea and constipation, mostly during dose escalation.
Heart rate increased in a dose-dependent way, an effect attributed to the glucagon component and still being characterized.
Skin sensations such as tingling and heightened sensitivity were reported more often than with placebo.
Long-term safety is unknown; trial follow-up so far covers less than two years.
Online products sold as retatrutide are unregulated, unverified and may contain the wrong substance, the wrong strength or contaminants.
Class-wide GLP-1 cautions, including thyroid C-cell tumor warnings from animal studies and pancreatitis risk, are assumed to apply until shown otherwise.
Where Retatrutide stands with the FDA
Retatrutide is investigational. No regulator anywhere has approved it, it is not on the FDA's 503A compounding list, and it cannot be legally prescribed or compounded outside a registered clinical trial. Phase 3 TRIUMPH trials are ongoing or reading out, and any approval timeline depends on those results and FDA review. Products sold online under the name retatrutide are unregulated and unsafe. The FDA-approved options a nurse practitioner can prescribe today are semaglutide and tirzepatide within a supervised weight-loss program.
Source: FDA compounding guidanceWhat Retatrutide typically costs
At Hormones + Weight Loss, peptide pricing runs from about $100 to $1,000 or more depending on the peptide and the quantity you order, and many patients start with a single peptide on a short cycle. Your exact cost is quoted after your consultation.
Retatrutide has no price because it cannot be legally purchased; trial participants receive it at no cost
GLP-1 program cost depends on semaglutide vs. tirzepatide, brand vs. compounded form and dose
Whether labs, InBody scans and follow-up visits are bundled into the program
Often combined with
Peptides are an add-on, not a plan. At Hormones + Weight Loss they are considered inside a broader, lab-guided program.
Retatrutide FAQs
Retatrutide is an investigational once-weekly injection from Eli Lilly that activates GLP-1, GIP and glucagon receptors. In a 2023 Phase 2 trial the highest dose produced about 24 percent average weight loss at 48 weeks. Phase 3 trials are ongoing, and it is not approved for use anywhere.
No. retatrutide is investigational, available only inside clinical trials. Approval depends on Phase 3 TRIUMPH results and FDA review, and no date has been set. Until then it cannot be legally prescribed or compounded, and any product sold under its name is unregulated.
No. Retatrutide is not available anywhere outside registered clinical trials, including at our Meridian, Twin Falls and Lewiston clinics, where Boise-area patients are seen in Meridian. What a nurse practitioner can discuss today is FDA-approved GLP-1 therapy, semaglutide or tirzepatide, inside our medically supervised weight-loss program.
Semaglutide targets one receptor, tirzepatide two, and investigational retatrutide three. Trial weight loss roughly rises in that order, though the studies are not head-to-head. The key difference today is availability: semaglutide and tirzepatide are FDA-approved and prescribable; retatrutide is not. Our comparison article covers the details.
In trials the most common were nausea, vomiting, diarrhea and constipation, mostly during dose increases, plus a dose-related rise in heart rate and skin sensations such as tingling. Long-term safety is unknown because follow-up is still short. Online products carry additional risks because their contents are unverified.
Retatrutide is not for sale anywhere outside clinical trials, so there is no price. For weight loss today, our nurse practitioners work with FDA-approved GLP-1 options inside a supervised program, and that cost is quoted after your consultation.
No. Products marketed online as retatrutide are not the investigational drug, are not made under regulated conditions, and may contain the wrong substance, strength or contaminants. There is no monitoring and no legal pathway for personal use. A nurse practitioner can offer approved GLP-1 therapy with proper oversight instead.
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Peptide therapy near you in Idaho
Consultations at all three clinics. Boise-area patients are seen at our Meridian clinic, minutes off Eagle Road and I-84.
Meridian
2572 N Stokesberry Pl #300
Meridian, ID 83646
Mon–Fri 8am–6pm
Twin Falls
496 Shoup Ave West Ste E
Twin Falls, ID 83301
Mon–Thu 8am–6pm
Lewiston
1630 23rd Ave Ste 1201A
Lewiston, ID 83501
Mon–Wed 8am–6pm
Educational content only. It does not replace an evaluation by a licensed clinician. Whether a peptide fits you is decided at your consultation.
Wondering whether Retatrutide fits your goals?
Start with a consultation and labs. A nurse practitioner will walk through the evidence, the current rules, and whether any peptide belongs in your plan.