Retatrutide with cagrilintide dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Retatrutide with cagrilintide is two unapproved drugs still being tested, premixed by research chemical sellers.
Evidence grade for Retatrutide with cagrilintide: Strong. The rule: at least two finished studies in people, and at least 1,000 people who took it. The sum on this page: 4 completed trials, 4,557 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 4,557
- Human studies
- 4
- Found nothing
- 1
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
4 completed trials, 4,557 people given it
6 effects reported, 4 unwanted, 2 wanted, by people using it, not a trial
Goal pages: Fat loss and metabolism
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Two drugs that are still in testing, mixed in a vial by a research chemical seller. A common one is 12.5 mg retatrutide with 2.5 mg cagrilintide. Neither drug is approved anywhere. No pharmacy makes this. No clinic prescribes it.
What people take it for
- Losing a lot of weight, fast.
- Turning down hunger harder than one drug can.
- Breaking a plateau on a single drug.
What studies in people showed
Nobody has tested this pair, in people or animals. Each half is good on its own. Retatrutide took off 24.2 percent of body weight at 48 weeks on the 12 mg dose, against 2.1 percent on a dummy shot. At that dose, 83 percent of people lost 15 percent or more. The stomach side effects were dose related and a lower starting dose helped. Heart rate went up with dose. Cagrilintide alone took off 6.0 to 10.8 percent at 26 weeks against 3.0 percent on a dummy shot. The pairing idea has been tested, with a different partner drug. Cagrilintide with semaglutide reached 20.4 percent weight loss at 68 weeks in 3,417 people. The math: 12.5 plus 2.5 is 15 mg, so the vial is 83.3 percent retatrutide and a fixed 5 to 1 split. Mix with 3 mL and every unit mark carries about 42 micrograms of retatrutide and 8 of cagrilintide. Some sellers use 10 plus 2.5, so read your label.
What people report
Reports, not study results
The good
- Hunger goes very quiet, stronger than either alone.
- Weight comes off fast.
The bad
- Bad nausea and vomiting, more often than on single drug vials, and worst at dose steps.
- A higher resting heart rate, which matches what the retatrutide trial found.
- Fast weight loss with visible muscle loss in people who are not lifting.
- You cannot back one off. The ratio is fixed, and both drugs are stepped up slowly in their own trials for a reason.
Where these come from: Patient forums and seller listings. People talking, using material nobody has tested. The heart rate rise is the one item that also shows up in the real trial.
My bottom line
Both halves are real drugs that are not finished yet. Mixing them at a fixed ratio from an untested vial takes the idea and throws away every safety rail the trials had.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Retatrutide with cagrilintide has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Losing weight3,755 people · 2 studies
What people using it report
Real people telling you what happened to them. Nobody checked it, and the people who post are not a fair sample, so it cannot prove anything works. It is still the best guide on this page to what people actually do with Retatrutide with cagrilintide, what they expect, and what goes wrong. The full account, including the negative reports, is below.
34 of the 36 indexed goals have no study of any kind behind Retatrutide with cagrilintide
No study in people, animals or cells on this page reports a result for these. That does not prove Retatrutide with cagrilintide does nothing for them. It does mean anything you have heard about Retatrutide with cagrilintide and one of these did not come from a study cited here.
Show full evidence
What is Retatrutide with cagrilintide?
Retatrutide with cagrilintide is two unapproved drugs still being tested, premixed by research chemical sellers. The usual vial is 12.5 mg retatrutide with 2.5 mg cagrilintide. Neither drug has finished testing. No pharmacy or clinic supplies the pair. The mix has never been tested in people or animals. Each drug alone has good early-stage data in people, and that is what makes this look safer than it is.
It is worth being exact about why this product carries so much risk. Both ingredients are real drugs in testing, with real studies. Retatrutide copies three gut and blood sugar hormones: GIP, GLP-1 and glucagon. In its early-stage obesity study, people on 12 mg lost 24.2% of their weight on average at 48 weeks, against 2.1% on a dummy shot. Cagrilintide is a long-acting copy of amylin, a fullness hormone. In its early-stage study, people lost 6.0% to 10.8% across doses at 26 weeks, against 3.0% on a dummy shot.
Neither is approved anywhere. Both are still being tested. There is no legal supply of either for people to use. So every vial of this blend comes from a research chemical seller, unchecked, with no pharmacy involved. That is different from pharmacy-made GLP-1 drugs, where at least the main ingredient is approved somewhere in the world.
The math on the common 12.5 plus 2.5 mg vial. There is 15 mg of powder. Retatrutide is 83.3% of it and cagrilintide 16.7%, a fixed 5 to 1 mix. Add 3 mL of water and each mL holds 5 mg in all: 4.17 mg of retatrutide and 0.83 mg of cagrilintide. One mark on a 100 unit insulin syringe holds about 42 micrograms of retatrutide and 8 micrograms of cagrilintide. To get 2 mg of retatrutide you draw about 48 units. That also gives you 0.4 mg of cagrilintide. Some sellers sell 10 plus 2.5, a 4 to 1 mix. So the split is not standard, and the label decides the math.
The fixed mix is the real problem. In its study, retatrutide was stepped up over months, from 2 mg starting doses up to 12 mg. That was because the stomach side effects grew with the dose, and a lower start helped. Cagrilintide has its own step-up. A fixed 5 to 1 blend forces both to step up together on one plan. So if nausea means you need to hold or lower one, you lower the other just as much, whether or not it was the problem.
There is also a heart note that belongs here. In retatrutide's early study, heart rate went up with the dose and peaked during the study. Amylin copies have their own side effects. Nobody has measured what the two do to heart rate together.
How does Retatrutide with cagrilintide work?
Retatrutide presses three switches: GIP, GLP-1 and glucagon. The glucagon switch is what sets it apart. It is also the one that burns more energy, and it can raise heart rate and change how much sugar the liver puts out. Cagrilintide copies amylin, a fullness hormone, and works on fullness through a separate path. The idea behind mixing them is that the amylin and gut hormone fullness signals add up. That has been shown for a different amylin and gut hormone pair, but never for this one.
What have studies in people found about Retatrutide with cagrilintide?
Each drug has early-stage data in people on its own. The mix has none. The version of this idea that was fully developed used a different gut hormone drug.
- The amylin plus gut hormone idea: cagrilintide with semaglutide reached 20.4% average weight loss at 68 weeks, in a large final-stage study of 3,417 people. 79.6% of the pair group had stomach side effects.
- Retatrutide alone: 24.2% average weight loss at 48 weeks on 12 mg, against 2.1% on a dummy shot. Heart rate went up with the dose.
- Cagrilintide alone: 6.0% to 10.8% weight loss across doses at 26 weeks, against 3.0% on a dummy shot.
- Amylin plus retatrutide: never tested in people.
- This blend: no published study and no listed trial.
What this does not tell you: The pairing that worked used semaglutide, which presses only the GLP-1 switch. Retatrutide also presses the GIP and glucagon switches. The glucagon switch has its own effects on the heart and liver. Nothing from the semaglutide pairing carries over.
What do people who took Retatrutide with cagrilintide report?
This is what real people say happened to them, good and bad. Nobody measured it. A report cannot tell a real effect from the lift people get just from expecting it to work, from a diet or training change made at the same time, or from what was really in the vial. We still put it near the top. It is the next best thing to a study in people: what happens when real people use it, including what goes wrong.
- Very strong appetite loss, described as stronger than either drug alone.
- Bad nausea and vomiting, more often than with single-drug vials, and often at step-up points.
- Higher resting heart rate. This matches the dose-linked rise seen in the retatrutide study.
- Fast weight loss with visible muscle loss, from people not lifting weights.
- Trouble backing off one drug. This is the built-in complaint about this vial.
Sources: Forums including r/Retatrutide and r/peptides, plus vendor listings. The heart rate observation also appears in the retatrutide phase 2 trial; everything else here is uncontrolled self-report from people using unverified material.
The state of the research
The most useful thing to compare this vial with is the REDEFINE 1 study. The drug company version of the same idea, an amylin copy given with a gut hormone drug, went through a final-stage study of 3,417 people. It reached 20.4% average weight loss at 68 weeks. It also gave stomach side effects to nearly four out of five people. That is what a developed, stepped-up, watched version of this idea looks like, cost included.
Retatrutide alone reached 24.2% at 48 weeks in its early study. Adding an amylin copy to it, at a fixed mix, bought from a research seller, is not clearly better than either. It is certainly a step outside any data. Both drugs are still being tested. So their long-term safety is not known even in the studies, let alone in this mix.
The evidence, in charts
Fig. 1a · how many people
4,557people, across 4 studies in people cited here
| Study | People | Share |
|---|---|---|
| New England Journal of Medicine 2025 | 3,417 | 75% |
| The Lancet 2021 | 706 | 15% |
| New England Journal of Medicine 2023 | 338 | 7% |
| The Lancet 2021 | 96 | 2% |
One study holds 75% of these people, so the total rests more on one study than its size suggests. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
All 4 sources here are studies in people.
- Study in people · done in people4100%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 3 different years, 2021 to 2025, counted from the list of sources on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Blend
- Molecule weight
- Not on file
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
Half-life as stated on file: Not defined for the blend. Both components support weekly dosing individually and no pharmacokinetic study of the mixture exists.
No amino acid sequence is on file for Retatrutide with cagrilintide, which is expected: a blend is not built from amino acids.
Fig. 6 · what is in the vial
83.3%of a 15 mg Retatrutide with cagrilintide vial is Retatrutide
- Retatrutide12.5 mg83.3%
- Cagrilintide2.5 mg16.7%
What the label says is in a standard vial. It is not a dose, and not a lab test. The seller fixes the mix, so when you draw the amount you want of one ingredient, you get a set amount of every other one with it. No study has tested this mix in people or animals.
The studies we cite
- Study in people2023Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Retatrutide caused very large weight loss, in an early, fairly small study. 338 adults with obesity took a weekly shot at one of four strengths, or a dummy shot, for 11 months. Average weight fell 8.7% at the lowest dose and 24.2% at the highest, against 2.1% on the dummy. At the top dose more than four in five lost at least a sixth of their body weight. Stomach and bowel upsets were common and rose with the dose. So did resting heart rate.
338 adults with obesity. Least-squares mean weight change at 48 weeks was 8.7% on 1 mg, 17.1% on 4 mg, 22.8% on 8 mg and 24.2% on 12 mg, against 2.1% on placebo. At 12 mg, 83% lost 15% or more of body weight against 2% on placebo. The most common adverse events were gastrointestinal, dose-related, and partially mitigated by a lower 2 mg starting dose. Dose-dependent increases in heart rate were reported. Retatrutide alone.
- Study in people2021Once-weekly cagrilintide for weight management in people with overweight and obesity: a multicentre, randomised, double-blind, placebo-controlled and active-controlled, dose-finding phase 2 trial
Cagrilintide on its own causes moderate weight loss. 706 adults were put by chance into groups: several cagrilintide strengths, a liraglutide group, and a dummy shot. After six months average weight was down between 6.0% and 10.8% depending on dose, against 3.0% on the dummy. That is a real gap of roughly 3 to 8 points. This was cagrilintide alone. The study was built to find a dose, not to prove a benefit.
706 adults randomised across cagrilintide 0.3 to 4.5 mg, plus liraglutide 3.0 mg and placebo arms. Mean weight reductions at 26 weeks were 6.0% to 10.8% across cagrilintide doses against 3.0% on placebo, with estimated treatment differences of 3.0 to 7.8 percentage points. Cagrilintide alone, in a monotherapy dose-finding trial.
- Study in people2021Safety, tolerability, pharmacokinetics, and pharmacodynamics of concomitant administration of multiple doses of cagrilintide with semaglutide 2·4 mg for weight management: a randomised, controlled, phase 1b trial
This is the closest thing to evidence for mixing an amylin drug with a gut hormone drug. It is a safety and dosing study, not a weight loss test. 96 people got weekly cagrilintide at one of several strengths, or a dummy, along with weekly semaglutide 2.4 mg. Both were stepped up over four months. Of 566 side effects reported, 207 were stomach and bowel problems. Cagrilintide did not change how much semaglutide got into the body. The gut hormone drug here was semaglutide, not retatrutide.
96 people randomised to weekly cagrilintide 0.16 to 4.5 mg or placebo, each in combination with weekly semaglutide 2.4 mg, doses co-escalated over 16 weeks. Of 566 adverse events, 207 were gastrointestinal disorders. Cagrilintide exposure was dose-proportional and did not affect semaglutide exposure. This is the closest thing to combination evidence for an amylin analogue with an incretin, and the incretin was semaglutide rather than retatrutide.
- Study in people2025Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity
A properly developed amylin and gut hormone pairing does exist. It has been tested in a very large study, and it is not this one. 3,417 people took cagrilintide with semaglutide, mixed by the maker, or a dummy shot. After about 16 months average weight was down 20.4%, against 3.0% on the dummy. That is a gap of more than 17 points. Stomach and bowel side effects hit about 80 in every 100 people on the pair, against 40 in 100 on the dummy. That is the cost side.
REDEFINE 1, 3,417 participants. Estimated mean weight change from baseline to week 68 was 20.4% on cagrilintide-semaglutide against 3.0% on placebo, a difference of 17.3 percentage points. Gastrointestinal adverse events affected 79.6% of the combination group against 39.9% on placebo. A developed, co-formulated amylin and incretin combination does exist and has been trialled at scale; it is not this one.
Where to buy Retatrutide with cagrilintide
4 sellers list Retatrutide with cagrilintide in our latest read. They are ranked by trust score, then by archive rating, then by certificate tier, then by the lowest price per milligram. Archive evidence is counted before source-backed. Each path is out of 4, and the two are not added. A higher price does not raise the score. The letter is the certificate chip. 0 of them have a published certificate that names Retatrutide with cagrilintide.
Some seller links may pay this site when you buy through them. A payment never changes a seller's tier or rank, and no seller has a say in any page.
| Seller | Trust score | Vial sizes | From, per mg | Certificate for Retatrutide with cagrilintide | Seller link |
|---|---|---|---|---|---|
| GenPeptide | 80 StrongSource-backed 4 of 4. Archive evidence 2 of 4.A | 2.5 mg | $48.0 | None found for Retatrutide with cagrilintide | View |
| EZ Peptides | 75 StrongSource-backed 4 of 4. Archive evidence 3 of 4.A | 12.5 mg | $9.44 | None found for Retatrutide with cagrilintide | View |
| AIO Peptides | 66 FairSource-backed 3 of 4. Archive evidence 1 of 4.B | 5 mg | $23.7 | None found for Retatrutide with cagrilintide | View |
| Platinum Lion Peptides | 0 InsufficientSource-backed 3 of 4. Archive evidence 1 of 4.Letter withheld | 2.5 mg, 5 mg | $30.0 | None found for Retatrutide with cagrilintide | View |
- LC Lab-confirmed: the issuing laboratory echoed this certificate back
- A Current certificate, independent laboratory named, laboratory not yet checked
- B Certificate published, but no laboratory link, older than a year, or the laboratory did not recognise the published lookup
- C No certificate could be read
Every listing and vial size for Retatrutide with cagrilintide · How the trust score is counted
Sellers named on the price pages are ranked by certificate tier, then price, and any affiliate income is disclosed there. Naming a seller is not a recommendation to buy or use anything.
Common questions
Has Retatrutide with cagrilintide been tested in people?
Yes. 4,557 people given it across 4 completed trials cited here, 1 of which found nothing. Retatrutide with cagrilintide is two unapproved drugs still being tested, premixed by research chemical sellers.
What is the Retatrutide with cagrilintide dosage?
No human dose established. Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose. 4 completed trials, 4,557 people given it
Is Retatrutide with cagrilintide FDA-approved?
Neither part is approved anywhere in the world. Both are investigational, and no regulator has reviewed the combination.
Has this combination been studied?
No, in people or animals. The related pair that has been studied is cagrilintide with semaglutide. It reached 20.4% average weight loss at 68 weeks in a large final-stage study of 3,417 people. That used a different gut hormone drug.
What is in the vial and in what ratio?
The most common listing is 12.5 mg retatrutide with 2.5 mg cagrilintide. That is a fixed 5 to 1 mix, 83.3% retatrutide by weight. Some sellers sell 10 plus 2.5. Mixed with 3 mL of water, one unit holds about 42 micrograms of retatrutide and 8 micrograms of cagrilintide.
Why does the fixed ratio matter here more than usual?
Because both drugs were stepped up slowly in their own studies, to make them easier to take. Retatrutide's stomach side effects grew with the dose, and a lower starting dose helped. A fixed blend means you cannot hold one and keep going with the other.
Is either drug approved?
Neither, anywhere. Both are still being tested. That is why no pharmacy or clinic supplies this, and every vial comes from a research chemical seller.
What about heart rate?
In retatrutide's early study, heart rate went up with the dose. Nobody has measured what happens to heart rate when it is mixed with an amylin copy.