Is retatrutide stronger than Ozempic? On weight loss, the trial numbers say yes, by a wide margin. In Lilly’s TRIUMPH-1 phase 3 trial, people on the top tested dose of retatrutide lost an average of 28.3% of their body weight over 80 weeks. In STEP-1, semaglutide (the drug in Ozempic) at the 2.4 mg obesity dose produced 14.9% over 68 weeks. These were separate trials, though. No trial cited here put the two drugs side by side.
The bigger difference is status. Ozempic is a Health Canada–approved diabetes medicine, generic semaglutide reached Canadian pharmacies in May 2026, and semaglutide has a large cardiovascular outcomes trial behind it. Retatrutide is not approved anywhere. Lilly plans to file with the FDA in Q1 2027, and outside clinical trials you can’t get it legally as a medicine.
Ozempic is a one-receptor drug (GLP-1). Retatrutide hits three (GLP-1, GIP and glucagon). That’s why it’s stronger, and probably why it comes with more stomach side effects and a new one called dysesthesia.
Ozempic and retatrutide: what each one is
If you know Ozempic, you already know half of this comparison. Ozempic is Novo Nordisk’s brand name for semaglutide, a once-weekly injectable medicine. In Canada, its official uses are lowering blood sugar in adults with type 2 diabetes and helping prevent kidney disease from getting worse in people who have both chronic kidney disease and type 2 diabetes. Weight loss is not one of its listed indications. The Canadian patient leaflet lists weight loss only as a possible side effect.[10] The same molecule at a higher dose, sold as Wegovy and its generic equivalents, is the version made for weight management.
Retatrutide (code name LY3437943) is Eli Lilly’s experimental follow-up to tirzepatide (Mounjaro/Zepbound). It’s also given once weekly. It’s still in phase 3 trials, and Lilly says plainly that it is “legally available only to participants in Lilly’s clinical trials.”[7] Online you’ll see it called “Reta”, “RT3” or “GLP-3”. We explain where those names come from in GLP-3, RT3, Reta: why retatrutide has so many names.
So this isn’t really “brand A vs brand B”. It’s an approved, well-studied, now-generic medicine against a next-generation drug that has posted impressive trial results but hasn’t been through a regulator’s review. Keep that in mind for every section below. For the full three-way data comparison that includes tirzepatide, see Retatrutide vs tirzepatide vs semaglutide.
Mechanism: 1 receptor vs 3
Both drugs copy hormones your gut and pancreas already make. The difference is how many of those signals each one copies.
Ozempic (semaglutide): GLP-1 only
Semaglutide activates the GLP-1 receptor. GLP-1 is a hormone released after you eat. It tells the pancreas to release insulin when blood sugar is high, holds back glucagon, slows how fast the stomach empties, and acts on appetite centres in the brain. You end up feeling full sooner and for longer. That one pathway is enough for big effects on blood sugar and meaningful weight loss.
Retatrutide: GLP-1 + GIP + glucagon
Retatrutide was designed to hit three receptors at once: GLP-1, GIP (another gut hormone that affects insulin and fat metabolism) and glucagon.[1] The glucagon part is what makes it unusual. Glucagon normally raises blood sugar, so adding it sounds backwards. In Lilly’s discovery work, though, the glucagon-receptor activity increased energy expenditure in mice. That added to the appetite reduction from the GLP-1 and GIP arms, and the combination produced more weight loss.[1] Glucagon signalling also acts directly on the liver, which may help explain the large drops in liver fat covered below.
| Receptor | Ozempic (semaglutide) | Retatrutide |
|---|---|---|
| GLP-1 | Yes | Yes |
| GIP | No | Yes |
| Glucagon | No | Yes |
| Nickname | “GLP-1” | “Triple agonist”, “triple G”, “GLP-3” (informal) |
Tirzepatide sits in the middle with two receptors (GLP-1 + GIP). If you want that piece, see our tirzepatide research guide.
Weight loss: STEP-1 vs the retatrutide trials
This is the comparison most people are searching for. Here’s what each drug’s key trials actually found.
Semaglutide: STEP-1
STEP-1 is the landmark semaglutide obesity trial. It enrolled 1,961 adults with obesity, or overweight plus a related health problem, all without diabetes. They took semaglutide 2.4 mg (the Wegovy dose, higher than any Ozempic dose) or placebo for 68 weeks, on top of lifestyle counselling.[2]
- Average weight change: −14.9% with semaglutide vs −2.4% with placebo.
- Lost 15% or more: 50.5% vs 4.9%.
- Lost 20% or more: 32.0% vs 1.7%.
Retatrutide: phase 2
The 2023 phase 2 trial in NEJM enrolled 338 adults with obesity and no diabetes. At 48 weeks, average weight loss reached −24.2% in the 12 mg group vs −2.1% with placebo. In that group, 83% lost at least 15% of their body weight, compared with 2% on placebo.[3]
Retatrutide: phase 3 (TRIUMPH)
The phase 3 program has now reported several trials:
- TRIUMPH-1 (May 2026): 2,339 adults with obesity or overweight and no diabetes, tested at 4, 9 and 12 mg once weekly for 80 weeks. Average weight change was −19.0%, −25.9% and −28.3% vs −2.2% on placebo (efficacy estimand). Counting everyone randomized, including people who stopped treatment (treatment-regimen estimand), the figures were −17.6%, −23.7% and −25.0% vs −3.9%. At the 12 mg dose, 45.3% lost 30% or more of their body weight.[7]
- TRIUMPH-4 (December 2025): 445 adults with obesity and knee osteoarthritis. At 68 weeks, weight change was −28.7% at 12 mg vs −2.1% on placebo, and knee pain scores dropped sharply.[8]
- TRIUMPH-2 and TRIUMPH-3 (July 2026): in people with type 2 diabetes, weight change was −12.7% to −20.8%. In people with established heart disease it was −21.6% to −22.6%, vs −3.2% to −4.0% on placebo, at 80 weeks.[9]
For a deeper dive on these readouts, see Retatrutide phase 3 results.
Why you can’t just subtract the numbers
Putting 14.9% next to 28.3% is a cross-trial comparison. The trials ran for different lengths of time (68 vs 80 weeks), enrolled different people (TRIUMPH-1 participants started at an average BMI of 40), used different estimands, and happened years apart. These differences can move results by several percentage points. The direction is very likely real, since retatrutide’s placebo-adjusted weight loss is roughly double. The exact gap is not something any of these trials measured.
Also note that STEP-1 tested the Wegovy dose. Ozempic’s own diabetes trials used lower doses and produced smaller weight changes. In SUSTAIN FORTE, people with type 2 diabetes lost about 6–7 kg over 40 weeks on Ozempic’s 1 mg and 2 mg doses.[4] People with diabetes also tend to lose less weight on these drugs than people without diabetes, as TRIUMPH-2 shows for retatrutide.
Blood sugar (A1c)
Ozempic exists because of blood sugar, so this is where it’s strongest on paper.
- Ozempic (SUSTAIN FORTE): 961 adults with type 2 diabetes and an average starting A1c of 8.9%. Over 40 weeks, A1c fell by 2.2 points on the 2 mg dose and 1.9 points on 1 mg.[4]
- Retatrutide (TRIUMPH-2): 1,152 adults with type 2 diabetes and an average starting A1c of 7.7%. A1c fell 1.4–1.6 points vs 0.2 on placebo at 80 weeks.[9]
The bottom line on blood sugar: both drugs lower A1c a lot, and the numbers overlap. The starting A1c strongly affects how big the drop looks, since people who start higher fall further. That is part of why SUSTAIN FORTE’s 2.2-point drop isn’t directly comparable to TRIUMPH-2’s 1.4–1.6. Where retatrutide clearly pulls ahead is weight loss in people with diabetes, which matters because extra weight makes diabetes harder to control.
Liver fat and fatty liver disease
Fatty liver disease, now called MASLD (and MASH when there’s inflammation), is one of the most interesting parts of this comparison.
- Retatrutide: a liver substudy of the phase 2 obesity trial enrolled 98 people with at least 10% liver fat on MRI. At the two highest doses, liver fat fell by roughly 80% or more in relative terms, and most participants in those groups reached the normal range (below 5%) by 48 weeks.[5]
- Semaglutide: the phase 3 ESSENCE trial took liver biopsies from people with biopsy-confirmed MASH and liver fibrosis. After 72 weeks, MASH resolved in 62.9% on semaglutide 2.4 mg vs 34.3% on placebo, and fibrosis improved in 36.8% vs 22.4%.[6]
These measure different things. Retatrutide’s data is MRI liver fat in a small phase 2 group. Semaglutide’s is biopsy-proven disease improvement in a large phase 3 trial, which is the kind of evidence regulators want. Retatrutide’s liver fat numbers are striking, but semaglutide currently has the stronger liver evidence. More on the condition itself in Fatty liver treatment in Canada.
Heart outcomes
This is the clearest win for semaglutide. The SELECT trial followed 17,604 adults with heart disease and overweight or obesity, without diabetes, for an average of about 40 months. Major cardiovascular events (heart attack, stroke or cardiovascular death) occurred in 6.5% on semaglutide 2.4 mg vs 8.0% on placebo, a 20% relative reduction (HR 0.80).[11]
Retatrutide doesn’t have that yet. TRIUMPH-3 enrolled people with established heart disease, but its prespecified heart-event analyses were inconclusive. The hazard ratio was 0.82 for a broad five-part composite and 1.12 for the classic three-part MACE composite, and both confidence intervals crossed 1.[9] So the trial neither showed benefit nor ruled out harm. In phase 2, retatrutide also raised heart rate in a dose-dependent way. The rise peaked around 24 weeks and declined afterward.[3] Lilly has a dedicated cardiovascular and renal outcomes study under way.[7]
Side effects compared
Both drugs mostly cause stomach and gut side effects, especially while the dose is being increased. Retatrutide’s rates run higher at its top doses.
| Side effect | Semaglutide 2.4 mg (STEP-1, 68 wk) | Retatrutide 4 / 9 / 12 mg (TRIUMPH-1, 80 wk) |
|---|---|---|
| Nausea | 44.2% (placebo 17.4%) | 28.6% / 38.4% / 42.4% (placebo 14.8%) |
| Diarrhea | 31.5% (placebo 15.9%) | 25.2% / 34.1% / 32.0% (placebo 13.5%) |
| Stopped due to side effects | 7.0% (placebo 3.1%) | 4.1% / 6.9% / 11.3% (placebo 4.9%) |
Sources: STEP-1[2]; TRIUMPH-1 topline[7]. Different trials, populations and durations, so compare with caution.
A few things stand out:
- Vomiting and dysesthesia. In TRIUMPH-1, vomiting hit 10.6% / 22.8% / 25.3% across the three doses vs 4.8% on placebo. Dysesthesia, a less familiar side effect, means unusual skin sensations such as tingling or sensitivity. It occurred in 5.1% / 12.3% / 12.5% vs 0.9% on placebo. Lilly described it as generally mild to moderate and said it mostly resolved during treatment.[7] In TRIUMPH-4 it reached 20.9% at 12 mg.[8]
- Dropouts rise with dose. In TRIUMPH-4, 18.2% stopped retatrutide 12 mg because of side effects. Lilly noted that some of those stopped because of perceived excessive weight loss.[8] In TRIUMPH-3, the figure was 13.5% at 12 mg vs 4.8% on placebo.[9]
- Ozempic’s serious warning. The Canadian Ozempic leaflet warns that semaglutide caused medullary thyroid tumours in rats and mice. It isn’t known whether this happens in people, and it shouldn’t be used by anyone with a personal or family history of medullary thyroid carcinoma or MEN 2.[10] Retatrutide hasn’t been through regulatory review, so it has no approved label yet.
Both drugs can cause a lot of weight loss, and some of what’s lost is lean mass. See Muscle loss on GLP-1 drugs and Hair loss on Ozempic. For the full safety picture on the newer drug, read Retatrutide side effects and Is retatrutide safe?
Approval and availability in Canada
Ozempic and generic semaglutide
- Ozempic is authorized by Health Canada for adults with type 2 diabetes. It’s also authorized to help prevent kidney disease from getting worse in people with chronic kidney disease and type 2 diabetes. It needs a prescription.[10]
- Generic semaglutide arrived in 2026. Health Canada approved the first generic Ozempic (Dr. Reddy’s) on April 28, 2026, followed by Apotex. On June 29, 2026 it approved Sevmia (Apotex), a generic equivalent of Wegovy for weight management in people 12 and older, the third generic semaglutide. Six more generic submissions were under review at that point.[12]
- Apotex began shipping its generic Ozempic on May 19, 2026, and Dr. Reddy’s reached select pharmacies the same week. Under provincial rules, pharmacists can generally substitute the generic for the brand unless your prescriber says otherwise or there’s a clinical reason not to.[13] More on this in Generic Ozempic in Canada.
Retatrutide
- Not approved in Canada, the US or anywhere else as of October 2026. Lilly plans to submit its US application in Q1 2027, once its manufacturing (CMC) package is complete.[9] Even with a standard review, that puts any approval well after the filing. We track the timeline in Is retatrutide approved?
- Health Canada’s April 2026 consumer advisory names retatrutide among unauthorized peptides it says Canadians should not buy or use. It also states that a “For Research Use Only” label does not exempt a product from regulation.[14]
Price in Canada
For patients, the price story in 2026 is all about semaglutide getting cheaper.
| Option | Typical cash price (CAD) | Notes |
|---|---|---|
| Brand Ozempic | About $258–$282 / month | Ontario pharmacy cash prices incl. dispensing fee, surveyed June 2026[15] |
| Generic semaglutide (Ozempic generic) | About $89–$104 / month | Same survey (Costco, Rexall, Shoppers)[15]; Apotex priced at about one-third of brand[13] |
| Online platform (Felix) | $150 / month | Announced at launch, May 2026[13] |
| Retatrutide (as a medicine) | No legal price | Not approved; available only in clinical trials[7] |
Prices vary by province, pharmacy, dose and dispensing fee. Coverage is decided separately by each provincial plan and private insurer, so ask your pharmacist what your plan pays.[13] Under pan-Canadian generic pricing rules, generics must be at least 50% cheaper than the brand once two are on the market.[12] For a broader view, see Weight loss injections in Canada.
Who each one makes sense for
This part is for patients, and the honest answer is short: any treatment decision goes through your doctor or nurse practitioner. Here’s how the evidence lines up.
Ozempic / semaglutide is the realistic option today if you:
- Have type 2 diabetes. That’s Ozempic’s actual indication, and it has years of real-world use behind it.
- Have heart disease along with overweight or obesity, since semaglutide has the SELECT outcomes data.[11]
- Want something approved, prescribed, pharmacy-dispensed and, since 2026, much cheaper as a generic.
- Are looking at weight management. The weight-management version (Wegovy, or generic Sevmia) is the one approved for that use.[12]
Retatrutide is something to watch if you:
- Have severe obesity and haven’t reached your goals with current medicines. That’s the group in which retatrutide’s results look most dramatic.
- Want to join a clinical trial. That’s the only legal way patients can receive it right now.[7] Ask your doctor or check trial registries.
If you’re weighing the whole market, including tirzepatide and the pills coming next, our overview of the next weight-loss drugs after Ozempic lays out the pipeline.
The big comparison table
| Ozempic (semaglutide) | Retatrutide | |
|---|---|---|
| Maker | Novo Nordisk (generics now in Canada) | Eli Lilly |
| Receptors | 1 (GLP-1) | 3 (GLP-1, GIP, glucagon) |
| Format | Once-weekly injectable | Once-weekly injectable (in trials) |
| Best weight result (key trial) | −14.9% at 68 wk (2.4 mg, STEP-1) | −28.3% at 80 wk (12 mg, TRIUMPH-1) |
| A1c drop in type 2 diabetes | −2.2 points at 40 wk (2 mg, SUSTAIN FORTE) | −1.4 to −1.6 points at 80 wk (TRIUMPH-2) |
| Liver | Biopsy-proven MASH improvement (ESSENCE, phase 3) | Large MRI liver-fat drops (phase 2 substudy) |
| Heart outcomes | 20% fewer major CV events (SELECT) | Not yet established (TRIUMPH-3 inconclusive) |
| Main side effects | Nausea, diarrhea, vomiting, constipation | Same GI effects, often higher at top doses, plus dysesthesia |
| Health Canada status | Approved (T2D; CKD in T2D) | Not approved |
| Generic available | Yes, since May 2026 | No |
| Typical Canadian cash price | ~$258–$282/mo brand; ~$89–$104/mo generic | None (not legally sold as a medicine) |
Retatrutide vs Ozempic myths
“Myth: Retatrutide has been proven twice as good as Ozempic.”
None of the trials cited here compared the two drugs directly. The “about double” impression comes from setting separate trials side by side, and those trials differ in length, population and estimand. The gap is very likely real and large. “Proven twice as good” is not what the data says.
“Myth: Ozempic is a weight-loss drug.”
In Canada, Ozempic is authorized for type 2 diabetes and for kidney protection in people with diabetes and chronic kidney disease. Weight loss is a known effect, but the weight-management product is semaglutide at a different dose (Wegovy, now also generic Sevmia).[10][12]
“Myth: Retatrutide is basically approved; it’s just paperwork.”
Lilly hadn’t even filed its US application as of October 2026, and the plan is Q1 2027.[9] Regulators still have to review safety, including the heart-rate rise, dysesthesia and the unresolved cardiovascular picture, plus manufacturing quality.
“Myth: Stronger always means better.”
More weight loss usually comes with more side effects. TRIUMPH-4 showed that some people stopped because they were losing too much weight.[8] For many patients, a well-understood drug with outcomes data is the better fit.
“Myth: GLP-3 is a newer, better hormone than GLP-1.”
There is no hormone called GLP-3. It’s an internet nickname for retatrutide’s triple action. See why “GLP-3” is technically wrong.
For researchers
Ozempic and generic semaglutide are prescription medicines for patients, handled by a doctor and pharmacist. Retatrutide’s place right now is in research. TrueLabs supplies RT3 (Retatrutide) from $90, along with TZ-2 (Tirzepatide) from $73 and Cagrilintide from $40, for in vitro and laboratory research only. Each lot is checked for purity by HPLC and identity by mass spectrometry. To check what you’re reading on a certificate, see How to read a peptide COA and the COA library. If you’re new to the compound, start with What is retatrutide?
FAQ
Tap a question to reveal the answer.
Is retatrutide stronger than Ozempic?
For weight loss, the trial data strongly suggests so. Retatrutide produced up to 28.3% average weight loss at 80 weeks in TRIUMPH-1, while semaglutide 2.4 mg produced 14.9% at 68 weeks in STEP-1. These were separate trials, though, so the exact gap is unknown. For blood sugar, the two look broadly similar.
What is the difference between retatrutide and semaglutide?
Semaglutide (Ozempic, Wegovy) activates one receptor, GLP-1. Retatrutide activates three: GLP-1, GIP and glucagon. Semaglutide is approved and now available as a generic in Canada. Retatrutide is still experimental and isn’t approved anywhere.
Is retatrutide approved in Canada?
No. As of October 2026 retatrutide is not approved by Health Canada or any other regulator. Lilly plans to submit its US application in Q1 2027, and the drug is legally available to patients only through Lilly’s clinical trials.
Can I switch from Ozempic to retatrutide?
Not as a prescribed medicine, because retatrutide isn’t approved. If you’re interested, ask your doctor about clinical trials. Any change to a diabetes or weight medicine should be planned with your doctor or pharmacist.
Does retatrutide have more side effects than Ozempic?
At its higher trial doses, retatrutide showed nausea and diarrhea rates similar to or higher than semaglutide 2.4 mg in STEP-1, more vomiting, and a new effect called dysesthesia (unusual skin sensations). Dropouts due to side effects reached 11–18% at the 12 mg dose in phase 3, depending on the trial.
How much does Ozempic cost in Canada in 2026?
A June 2026 survey of Ontario pharmacies found brand Ozempic at roughly $258–$282 a month and generic semaglutide at about $89–$104 a month, cash price including dispensing fees. Your price depends on your province, pharmacy and coverage.
Is there a generic Ozempic in Canada?
Yes. Health Canada approved the first generic Ozempic on April 28, 2026, and generics from Apotex and Dr. Reddy’s reached pharmacies in May 2026. A generic Wegovy, Sevmia, was approved on June 29, 2026.
Is retatrutide better for type 2 diabetes than Ozempic?
It’s too early to say. Both lower A1c by around 1.4 to 2.2 points in their trials, depending on the study and starting A1c, and retatrutide causes more weight loss. Ozempic is approved, has kidney and heart data, and is affordable as a generic. Retatrutide has none of that yet.
What is “GLP-3”? Is it the same as retatrutide?
“GLP-3” is an informal nickname for retatrutide because it acts on three receptors. There is no natural hormone called GLP-3. The body makes GLP-1 and GLP-2, and GLP-2 has nothing to do with weight loss.
When will retatrutide be available?
Lilly plans to file in the US in Q1 2027. Approval would come after that review, and a Canadian submission would follow its own timeline. Until then, clinical trials are the only legal route for patients.
Related reading
- Retatrutide vs tirzepatide vs semaglutide
- Generic Ozempic in Canada
- Retatrutide phase 3 results
- Retatrutide side effects
- Is retatrutide approved?
- GLP-3, RT3, Reta, LY3437943: retatrutide’s many names
References
- Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metab. 2022;34(9):1234-1247. PubMed
- Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002. PubMed
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. N Engl J Med. 2023;389:514-526. PubMed
- Frías JP, Auerbach P, Bajaj HS, et al. Efficacy and safety of once-weekly semaglutide 2.0 mg versus 1.0 mg in patients with type 2 diabetes (SUSTAIN FORTE): a double-blind, randomised, phase 3B trial. Lancet Diabetes Endocrinol. 2021;9(9):563-574. PubMed
- Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024;30:2037-2048. PubMed
- Sanyal AJ, Newsome PN, Kliers I, et al. Phase 3 trial of semaglutide in metabolic dysfunction-associated steatohepatitis (ESSENCE). N Engl J Med. 2025;392:2089-2099. PubMed
- Eli Lilly and Company. Lilly’s triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial (TRIUMPH-1 topline). Press release, May 21, 2026. Lilly
- Eli Lilly and Company. Lilly’s triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain (TRIUMPH-4 topline). Press release, December 11, 2025. Lilly
- HCPLive. Retatrutide meets phase 3 weight loss endpoints in 2 obesity trials (TRIUMPH-2 and TRIUMPH-3). July 23, 2026. HCPLive
- Novo Nordisk Canada Inc. Ozempic (semaglutide injection) Patient Medication Information. Date of authorization November 4, 2025. Novo Nordisk Canada
- Lincoff AM, Brown-Frandsen K, Colhoun HM, et al.; SELECT Trial Investigators. Semaglutide and cardiovascular outcomes in obesity without diabetes. N Engl J Med. 2023;389(24):2221-2232. PubMed
- The Canadian Press (via Chronicle Journal). Canada approves generic version of Wegovy for weight loss. June 29, 2026. Chronicle Journal
- BNN Bloomberg / The Canadian Press. Generic semaglutide to hit Canadian pharmacies this week at a fraction of the cost of Ozempic. May 20, 2026. BNN Bloomberg
- Health Canada. Think twice before injecting peptides bought online: unauthorized products can seriously harm your health. Public advisory, April 9, 2026. Health Canada
- TeleTest. Ozempic price in Canada (Ontario pharmacy cash-price survey). Updated June 9, 2026. TeleTest
This article summarizes published research and regulatory information for information only and is not medical advice. TrueLabs research compounds are sold for in vitro and laboratory research use only and are not intended for human or veterinary use.